HK40096910A - A method of controlling auto-exposure settings of a mobile device having a camera - Google Patents

Description

Method for controlling the automatic exposure settings of a camera-equipped moving device

Technical Field

This application relates to a method for controlling the automatic exposure settings of a mobile device having at least one camera, and a method for determining the concentration of an analyte in a sample using the mobile device. The invention further relates to a mobile device having at least one camera, to a kit for determining the concentration of at least one analyte in a body fluid sample, and further to a computer program and a computer-readable storage medium. These methods, devices, computer programs, and storage media are specifically applicable in medical diagnostics for, for example, qualitative and/or quantitative detection of one or more analytes in one or more body fluids, such as for detecting glucose in blood and/or interstitial fluid. However, the invention is also applicable to other fields.

Background Technology

In the field of medical diagnostics, in many cases, it is necessary to detect the concentration of one or more analytes in samples of bodily fluids (e.g., blood, interstitial fluid, urine, saliva, or other types of bodily fluids). The analytes to be detected are, for example, glucose, triglycerides, lactate, cholesterol, or other types of analytes commonly present in these bodily fluids. Depending on the concentration and/or presence of the analytes, appropriate treatment methods may be selected, if necessary. Without narrowing its scope, the invention can be specifically described in relation to blood glucose measurement. However, it should be noted that the invention can also be used for other types of analytical measurements using test strips.

Generally, apparatuses and methods known to those skilled in the art utilize test strips comprising one or more test chemicals, wherein the one or more test chemicals are capable of performing one or more detectable detection reactions, such as optically detectable detection reactions, in the presence of the analyte to be detected. For example, reference can be made to J. Hoenes et al.: The Technology Behind Glucose Meters: Test Strips, Diabetes Technology & Therapeutics, Vol. 10, Supplement 1, 2008, pp. 10-26. Other types of test chemicals are feasible and can be used to carry out this invention.

Typically, one or more optically detectable changes in a test chemical substance are monitored in order to derive the concentration of at least one analyte to be detected from these changes. Various types of detectors (with various types of light sources for illuminating the test field) (also known as dedicated instruments or analytical measuring devices) are known for detecting at least one change in the optical properties of the test field of a test strip.

In addition to using custom detectors specifically developed for optical detection of changes in the test chemicals included in the test strips, recent developments aim to utilize widely available devices, such as smartphones. However, when using consumer electronic devices with cameras (such as smartphones) instead of dedicated analytical measuring devices to determine analyte concentrations, various influences need to be considered. For example, lighting conditions, positioning, or other more or less uncontrollable conditions will be taken into account.

US20170042451A1 describes how pixel values in images captured using a computing device (such as a smartphone) are highly dependent on the lighting present at the time the image was captured and the exposure of the image taken by the camera. Therefore, it is recommended to capture an image in which a reference card is also visible. Then, locations of pure gray with known reflectivity on the card are identified in the captured image, and the pixels at those locations are analyzed to normalize the image's exposure and white balance. This normalization is then applied to the average of selected pixels in the image to create corrected pixel values.

US10469807B2 describes a system for determining color matching using a template card that includes at least one reference scale. The system receives an image of the template card and a color sample, and applies color correction to the sample RGB values based on the difference between the RGB values of at least one reference scale and their corresponding calibrated RGB values to generate color-corrected sample RGB values. The color-corrected sample RGB values are then compared with RGB values of color definitions stored in a database to determine a color match. It is described that unknown camera gain and illumination effects may not affect the actual red, green, and blue color values because these effects affect the template card in the same way they affect the sample of unknown color. Therefore, the template card is described as being used as a reference card to eliminate many variations that may affect the perception or imaging of the unknown color sample. It is further described that, when the background color of the card is uniform and known, this fact can be used to calculate and subtract any smooth inhomogeneities, resulting in residual inhomogeneities several times smaller than the actual ones. This can be achieved by sampling multiple points in the template background image that are of the same known color and determining the difference in the image from the known color based on the location of that point, thus finding and removing smooth inhomogeneities.

US9903857B2 describes a test apparatus for performing analysis, comprising: a container containing a reagent that reacts with an applied test sample by color development of a color or pattern change; a mobile phone or laptop computer including a processor and an image capture device, wherein the processor is configured to process data captured by the image capture device and output test results for the applied test sample. It further describes that when the dynamic range of the resulting image is insufficient to reach the detection limit, or when the limitation of the average exposure setting forces the dynamic range to be too poor, it may be necessary to capture multiple images at different exposure settings and then combine these images into a single "virtual" image with a higher dynamic range, using appropriate algorithms to redirect the images between frames and discard unwanted or low-value data. Different shapes of contrasting colors (e.g., on the test strip shell) and shells are described to simplify image processing. In the absence of a shell or when the shell is a similar color to the test strip, it is disclosed that placing the test strip against a contrasting background during image capture may be preferred.

US9506855B2 discloses a challenge in everyday use of mobile phones for quantitative colorimetric analysis, beyond controlled settings, namely compensating for ambient light conditions. It describes how, when measuring 12 regions on a reference chart, the intensity measured under different ambient light conditions showed a linear relationship. The conclusion is that the reference colorimetric chart can be used to compensate for intensity differences caused by variations in ambient light. It also describes how the reference chart virtually eliminates the effects of automatic camera functionality, making images reproducible and quantifiable. By including yellow, orange, and red regions, shifting the reference chart towards warmer colors overcomes the tendency of AWB to reduce the gain of CMOS imaging arrays in the red band, as silicon exhibits better response at these longer wavelengths.

While performing analytical measurements using mobile computing devices and color reference cards offers advantages, several technical challenges remain. Specifically, determining analyte concentrations using a mobile device via optical test strips often requires accurately determining the color variations of the test strips, which is generally challenging. Adequate image brightness must be ensured. The brightness observed in a captured image can depend on various influencing factors, such as the exposure settings determined at the time of image capture, including shutter speed, aperture size, and sensor gain, as well as post-processing steps applied to the image after capture. Specifically, the determination of exposure settings by the mobile device is typically a device-specific process performed in automatic exposure mode and may therefore be unknown to the manufacturer of the measurement application. Although images captured using automatic exposure mode generally have good overall or average brightness, there may be underexposed or overexposed areas that are darker or brighter than the image average. Applying intensity values that fall outside the representable minimum or maximum intensity will result in uniform areas of minimum or maximum brightness in the image, leading to a loss of image detail. If fundamental image elements (e.g., the test field) are therefore located within those underexposed or overexposed image areas, the image cannot be used to determine analyte concentrations.

Problems to be solved

Therefore, it is desirable to provide a method and apparatus that addresses the aforementioned technical challenges of using mobile devices, such as consumer electronic mobile devices, specifically multifunctional mobile devices not dedicated to analytical measurements, such as smartphones or tablets. Specifically, a method and apparatus for controlling the automatic exposure settings of the mobile device should be provided to ensure the acquisition of images suitable for reliably and accurately determining analyte concentrations. Furthermore, it is desirable to provide a method and apparatus that allows for user-friendly mobile determination of analytes in bodily fluid samples, with high accuracy and reliability in analytical measurements, and thus takes into account image brightness and device-specific aspects.

Summary of the Invention

This problem is solved by: an automatic exposure setting of a moving device having at least one camera when capturing at least one image of at least a portion of a color reference card and at least one image of at least a portion of a reagent test field to which an optical test strip of the sample is applied using a camera; a method for determining the concentration of an analyte in a sample using the moving device; a computer program, a computer-readable storage medium, a calculator-readable storage medium, a reagent kit, and a moving device having the features of the independent claims. Advantageous embodiments that can be implemented individually or in any arbitrary combination are set forth in the dependent claims.

As used below, the terms “have,” “contain,” or “include,” or any grammatical variation thereof, are used in a non-exclusive manner. Thus, these terms can refer either to a situation where no other features exist in the entity described in this context besides those introduced by these terms, or to a situation where one or more other features exist. For example, the statements “A has B,” “A contains B,” and “A includes B” can all refer to a situation where no other elements exist in A besides B (i.e., A consists only of B), and to a situation where entity A contains one or more other elements besides B, such as element C, elements C and D, or even other elements.

Furthermore, it should be noted that the terms "at least one," "one or more," or similar expressions indicating that a feature or element may exist once or more are generally used only once when the corresponding feature or element is introduced. In the following text, in most cases, when referring to the corresponding feature or element, the expressions "at least one" or "one or more" will not be used repeatedly, even though the corresponding feature or element may exist only once or more.

Furthermore, as used below, the terms "preferredly," "more preferably," "particularly," "more particularly," "specifically," "more specifically," or similar terms are used in combination with optional features without limiting the possibility of substitution. Therefore, features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As those skilled in the art will recognize, the invention can be practiced using alternative features. Similarly, features introduced by "in embodiments of the invention" or similar expressions are intended to be optional features, without limiting alternative embodiments of the invention, without limiting the scope of the invention, and without limiting the possibility of combining features introduced in this way with other optional or non-optional features of the invention.

In a first aspect, a method is disclosed for controlling the automatic exposure settings of a moving device having at least one camera when at least one image of at least a portion of a color reference card and at least one image of at least a portion of a reagent test field on which an optical test strip of a sample is applied are captured by using a camera.

The method includes the following steps:

a) Provide a color reference card and optical test strips with a test field on which the sample is applied.

The color reference card includes multiple distinct color reference fields with known reference color values and one or more gray background fields with defined grayscale values.

b) Set the exposure metering area, and determine the automatic exposure settings based on the scene within the set exposure metering area.

The scene set in the exposure metering includes at least a portion of a reagent test field on which an optical test strip of the sample is applied, at least a portion of the plurality of different color reference fields of the color reference card, and at least a portion of the one or more gray background fields.

c) Capture images of the scene including that in step b) using a camera.

The determined automatic exposure settings from step b) are used.

This method may include other steps not listed.

As used herein, the term "auto exposure setting" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to a specific or customary meaning. Specifically, the term may refer to, but is not limited to, automatically adjusted exposure parameter values of a camera to control the amount of light entering or exposing an image. Exposure can be adjusted, for example, by adjusting one or more of the exposure parameter values such as sensor gain, shutter speed or exposure time, lens aperture, or by adjusting any other camera operation used to change the camera's exposure parameter values. Sensor gain can be defined, for example, as a digital camera setting that controls the amplification of signals from one or more camera sensors. When adjusting sensor gain, signal amplification can be controlled individually for each sensor or a subset of the camera's sensors. Alternatively, when adjusting sensor gain, signal amplification can be controlled uniformly for all sensors of the camera. Increasing gain amplifies the signal by increasing the ratio of the digital-to-analog unit (ADU) to the electrons acquired on the sensor. As a result, increasing gain enhances the apparent brightness of the image. Shutter speed or exposure time can be defined, for example, as the length of time the camera shutter is open, exposing light to the camera sensor. A lens aperture refers to a hole or opening that restricts the amount of light that can pass through. While some mobile devices allow users to manually set exposure parameters, many smartphones (especially inexpensive ones) do not allow users to freely adjust exposure parameters such as sensor gain, shutter speed (exposure time), or lens aperture. These smartphones only offer an automatic exposure mode. For example, this automatic exposure mode attempts to capture an image so that the integrated intensity or brightness of the image meets predefined values. However, when the automatic exposure settings are determined based on an unsuitable scene within the set exposure metering range, this can result in inappropriate automatic exposure settings being used to capture an image that is unsuitable for determining the concentration of analytes in a sample.

The term "control" generally refers to the process of influencing or adjusting settings, or the process of determining settings in a defined or definable manner. When determining automatic exposure settings, the result (the determined automatic exposure settings) is affected by the scene or a portion of the scene to be imaged (or more specifically, the lighting conditions within the scene or a portion of the scene). Exposure metering zones can be set to determine which part of the scene (or the entire scene) in the camera's field of view is used by the camera to determine the automatic exposure settings.

As used herein, the term "mobile device" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to any particular or customary meaning. The term may specifically refer to, but is not limited to, mobile electronic devices, and more specifically to mobile communication devices such as mobile phones or smartphones. Additionally or alternatively, as will be further detailed below, the mobile device may also refer to a tablet computer or another type of portable computer having at least one camera.

As used herein, the term "camera" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to any particular or customary meaning. Specifically, the term may refer to, but is not limited to, an apparatus having at least one imaging element configured to record or capture spatially resolved one-dimensional, two-dimensional, or even three-dimensional optical data or information. The camera may specifically include one or more imaging devices, such as a camera chip or imaging chip, for example, a CCD and/or CMOS chip. The imaging device of the camera may specifically include a one-dimensional or two-dimensional array (such as pixels) of an image sensor. For example, the camera may include at least 10 pixels in at least one dimension, such as at least 10 pixels in each dimension. However, it should be noted that other cameras are also possible. In addition to at least one camera chip or imaging chip, the camera may also include additional elements, such as one or more optical elements, for example, one or more lenses. For example, the camera may be a fixed-focus camera having at least one lens that is fixedly adjusted relative to the camera. However, alternatively, the camera may also include one or more variable lenses that are automatically or manually adjusted. The camera may also include a diaphragm for controlling the aperture (thereby controlling the amount of light reaching the camera sensor). The diaphragm functions much like the iris of an eye—it controls the effective diameter of the lens opening (called the aperture). The camera could further include an ambient light sensor to measure the light reflected from the scene that will be captured in the image.

This invention is specifically applicable to cameras, such as those commonly used in mobile applications, like laptops, tablets, or specifically mobile phones, such as smartphones. Therefore, specifically, the camera can be part of a mobile device that, in addition to the at least one camera, includes one or more data processing devices, such as one or more data processors. However, other cameras are also feasible.

The camera can specifically be a color camera. Therefore, for example, for each pixel, color information can be provided or generated, such as color values for three colors: R, G, and B. A larger number of color values are also possible, such as four color values for each pixel, for example, R, G, G, and B. Color cameras are generally known to those skilled in the art. Therefore, for example, the camera chip can consist of three or more different color sensors, such as color recording pixels, one pixel for red (R), one pixel for green (G), and one pixel for blue (B). For each pixel, for example, for R, G, and B, a numerical value is recorded by the pixel according to the intensity of the corresponding color, for example, a digital value in the range of 0 to 255. Instead of using a color triplet such as R, G, and B, for example, a quadruple such as R, G, G, and B can be used. The color sensitivity of a pixel can be generated by a color filter or by the appropriate inherent sensitivity of the sensor elements used in the camera pixel; these techniques are generally known to those skilled in the art. For example, gain can be a digital camera setting that controls the amplification of the signal from the camera sensor.

As briefly described above, step a) includes providing a color reference card and an optical test strip with a test field on which the sample is applied.

As used herein, the term "optical test strip" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to a specific or customary meaning. The term specifically refers to, but is not limited to, strip-shaped elements or devices configured to perform a color change detection reaction. An optical test strip may also be referred to herein simply as a test strip, where these terms may refer to the same element. An optical test strip may particularly have a reagent test field comprising at least one test chemical substance for detecting at least one analyte. As an example, an optical test strip may comprise at least one substrate, such as at least one carrier, having at least one reagent test field applied thereto or integrated therein. In particular, an optical test strip may further comprise at least one white area, such as a white field, especially near the test field, such as surrounding or enclosing the test field. The white area may be a separate field arranged independently on the substrate or carrier. However, additionally or alternatively, the substrate or carrier itself may be or may comprise a white area. The at least one carrier may be strip-shaped, thus providing the basic form of a test strip. Such test strips are generally widely used and available. A test strip may have a single test field or multiple test fields, which may contain the same or different test chemicals.

As used further herein, the term “reagent test field” (also referred to as “test field”) is a broad term and will be given a common and customary meaning to those skilled in the art, and is not limited to a particular or customary meaning. The term may specifically refer to, but is not limited to, a coherent quantity of a test chemical substance, such as a field (e.g., a circular, polygonal, or rectangular field or area) having one or more layers of material, at least one layer of which contains the test chemical substance.

The test strip may be placed on top of the color reference card, and/or the color reference card may include one or more windows, wherein the color reference card having one or more windows is placed on top of the optical test strip so that the reagent test area is visible through the windows.

As used herein, the term "color reference card" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, any item having, disposed therein, or disposed on (e.g., on at least one surface) multiple different color reference fields having known color or optical properties, such as multiple color fields with known reference color values and further, one or more gray background fields with defined gray levels. For example, a color reference card may be a planar card comprising at least one substrate having and/or disposed therein on at least one surface multiple color reference fields with known color coordinates and one or more gray background fields with known gray levels. A color reference card may also include one or more additional gray fields. This will be further described below.

Specifically, the substrate may have a flat surface comprising a plurality of color reference fields, one or more gray background fields, and optionally (additional) gray fields disposed thereon (see below). As an example, the substrate may be or may include one or more of a paper substrate, cardboard substrate, plastic substrate, ceramic substrate, or metal substrate. It may also be a laminated substrate. As an example, the substrate may be sheet-like or flexible. However, it should be noted that the substrate may also be incorporated into the article of manufacture, such as into a box wall, vile, container, medical consumable (e.g., test strip), etc. Therefore, the color reference card may also be wholly or partially integrated into the optical test strip. Thus, at least one image of at least a portion of the color reference card may wholly or partially comprise an image of at least a portion of the optical test strip having at least one reagent test field.

Furthermore, the color reference card may include at least one location marker. As an example, the at least one location marker may be, or may specifically include, an ArUco code, etc. Specifically, the at least one location marker may be positioned at at least one corner of the color reference card. Therefore, the mobile device is configured to detect and/or read the marker, specifically by optical detection (e.g., of the marker in at least one image captured in step c), and, where appropriate, retrieve information from the marker, such as information about the position and/or orientation of the color reference card relative to the camera. The color reference card may include other markers containing additional information, or the location markers may additionally include additional information. Such additional information may include at least one of the following: an identifier for identifying the color reference card and/or the type of color reference card, such as at least one of a label, barcode, or QR code; a specifier specifying details of the color reference card (such as reference color values, gray background, and/or other grayscale values, etc.), such as by using at least one of a label, barcode, or QR code.

As used herein, the term "color reference field" is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a specific or customary meaning. Specifically, the term may refer to, but is not limited to, any item having known optical properties (e.g., known reference color values). Specifically, a color reference field composed of color reference cards may be a two-dimensional structure, such as a rectangle, square, polygon, circle, and/or ellipse, having uniform color values. The color values of the color reference field may specifically be one or more of predetermined color values, known color values, or determinable color values. The color reference field may be composed of and/or disposed therein by the surface of the color reference cards, specifically disposed in such a way that at least a portion (e.g., one color reference field) of the plurality of different color reference fields is visible in the image captured in step c). Furthermore, the color reference field may have color values in a subspace of a color coordinate system corresponding to the color space of the color-forming reaction in the reagent test area. The color reference fields of the color reference cards may specifically be arranged in a regular pattern on the surface of the color reference cards, for example, in a rectangular pattern (e.g., a rectangular matrix pattern). The pattern arrangement can specifically enable the identification of a color reference field, for example, by searching along the x and/or y directions at predetermined distances from one or more of the location markers.

Furthermore, the color reference fields may be locally distributed on the color reference card, specifically on a portion of the color reference card visible in the image. The color reference card includes at least two color reference fields with different reference color values. Specifically, the color reference card may include multiple color reference fields with different color values, wherein the color values of the color reference fields can be selected from a predetermined color subspace of the color space. The predetermined color subspace may include at least one color value of the color-forming reaction of the reagent test field.

As used herein, the term "known color reference value" is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, predetermined color values, actual color values, or true color values of a color reference field. Specifically, a known reference color value may include at least three color values, for example, at least one color value for each of the R, G, and B colors. The known reference color values for each color reference field may be stored in the data storage device of the mobile device, such as in a lookup table, register, database, etc. Known reference color values can be determined by measuring the corresponding color values, specifically by measuring color values in a controlled laboratory environment (e.g., using a spectrometer). Measuring a color reference field using a spectrometer defines the corresponding known reference color values.

As used herein, the term "gray background field" is a broad term and will be given a common and customary meaning to those skilled in the art, and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, any field of color or gray shades having known or determinable limitations and defined grayscale levels. Specifically, grayscale may refer to relative brightness values that indicate the proportion or percentage of black and white mixing. For example, a grayscale of 100% may indicate a black field, a grayscale of 0% may indicate a white field, and grayscale levels between 0% and 100% may indicate a mixture of black and white. One or more gray background fields included in a color reference card may specifically have defined and known RGB color values. For a color (r, g, b), a grayscale value is obtained when r = g = b. A gray background field may be a two-dimensional structure, such as a rectangle, square, polygon, circle, and/or ellipse, having a uniform grayscale. A gray background field may have an outline constructed around an arrangement of a color reference field (and optionally additional gray fields and position markers). As another example, substantially all areas of the color reference card, except for the color reference fields, other gray fields (if present), and location markers (if present) (and potentially the space on the color reference card used to place test strips), may be covered by one or more gray background fields. Furthermore, when a test strip is placed on top of or below the color reference card and portions of the test strip are visible through a window of the color reference card, one or more gray background fields included in the color reference card may be locally assigned to one or more test fields. Additionally, one or more gray background fields included in the color reference card may be locally assigned to multiple color reference fields and/or one or more other gray fields.

When facing a camera, one or more gray background fields may cover at least 5%, particularly at least 10% or at least 15%, of the surface of the color reference card.

As an example, one or more gray background fields can have defined gray values between 0% and 30% gray levels or between 70% and 100% gray levels. Using a gray background field with gray levels at the lower or upper ends of the gray spectrum can have a greater impact on the determination of automatic exposure settings compared to using a gray background field with gray levels in the middle of the gray spectrum. Specifically, one or more gray background fields can have defined gray values between 0% and 20% gray levels or between 80% and 100% gray levels. In one instance, one or more gray background fields can have defined gray values between 0% and 10% gray levels. In one instance, the gray background fields are characterized by all having the same gray value.

In one instance, in addition to one or more gray background fields, the reference card includes additional gray fields. These additional gray fields may have gray values different from those of the one or more gray background fields. Specifically, these additional gray fields may have gray levels between >30% and <70%. These additional gray fields may be two-dimensional structures, such as rectangles, squares, polygons, circles, and/or ellipses, with a uniform gray level. In one instance, each of these additional gray fields comprises a two-dimensional structure smaller than the two-dimensional structure of the largest gray background field on the color reference card.

When the test strip is placed on top of or below the color reference card and parts of the test strip are visible through the window of the color reference card, additional gray fields included in the reference card can be locally assigned to one or more test fields. Additional gray fields included in the color reference card can be locally assigned to multiple color reference fields and/or one or more gray background fields.

As used herein, the term "partially assigned" is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a particular or customary meaning. The term may specifically refer to, but is not limited to, a predetermined spatial arrangement between at least two objects, such as a standardized local arrangement. As an example, two or more objects may be locally assigned to each other by placing them in adjacent positions. Thus, when a test strip is placed behind a color reference card, additional gray fields may be placed adjacent to the test field. Additional gray fields may also be locally assigned to at least one color reference field on the color reference card such that these additional gray fields (at least partially) surround the at least one color reference field. Therefore, the term "local" may refer to the closest surrounding color reference field and/or reagent test field. Generally, if a first object is locally assigned to a second object, this assignment does not necessarily preclude the first object from also being locally assigned to at least one third object. As an example, a first object may be adjacent to at least one second object and at least one third object, thereby being assigned to both the second and third objects simultaneously.

An additional gray field can be used as a gray reference field from which local brightness information can be determined. One or more gray background fields can also be used as gray reference fields from which local brightness information can be determined. Local brightness information can be taken into account to determine an intensity-corrected image from at least one captured image.

For example, additional gray fields and optional gray background fields can be locally assigned to the test field. They can therefore surround the test field. Thus, the additional gray fields and optional gray background fields locally assigned to the test field, together with the test field, form a test field group. This test field group can therefore include multiple redundant additional gray fields and a redundant gray background field optionally having at least two or at least three different gray levels, wherein at least two, optionally at least three redundant gray fields can be provided for each gray level (here, the additional gray fields surrounding the test field and the gray background field are considered together as gray fields). Specifically, the redundant gray fields can be arranged symmetrically around the test field (more specifically, in a rotationally symmetric and/or mirror-symmetric manner). As an example, the local brightness information of the test field can be determined by averaging redundant gray fields having the same gray level. Specifically, the local brightness information can be determined by averaging the redundant gray fields relative to the distance between the gray fields and the test field. For example, averaging can include weighting the color values of the redundant gray fields with the reciprocal of the square of the distance between the redundant gray fields and the test field. Alternatively or additionally, averaging may include averaging each RGB color value individually.

Similarly, a color reference card may include additional gray fields and optional gray background fields locally assigned to a color reference field. These can therefore surround the color reference field. Thus, the additional gray fields and optional gray background fields locally assigned to the color reference field, together with the color reference field, can form a color reference field group. This color reference field group can therefore include multiple redundant additional gray fields and a redundant gray background field optionally having at least two or at least three different gray levels, wherein at least two, optionally at least three redundant gray fields can be provided for each gray level (here, the additional gray fields surrounding the test field and the gray background field are considered together as gray fields). Specifically, the redundant gray fields can be arranged symmetrically around the color reference field (more specifically, in a rotationally symmetric and/or mirror-symmetric manner). As an example, local brightness information of the color reference field can be determined by averaging redundant gray fields having the same gray level. Specifically, local brightness information can be determined by averaging the redundant gray fields relative to the distance between the gray fields and the color reference field. For example, averaging may include weighting the color values of the redundant gray fields with the reciprocal of the square of the distance between the redundant gray fields and the color reference field. Alternatively or additionally, averaging may include averaging each RGB color value individually.

As described above, step b) includes setting an exposure metering area and determining automatic exposure settings based on the scene within the set exposure metering area.

As used herein, the term "exposure metering zone" is a broad term and will be given a common and customary meaning to those skilled in the art, and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, the area considered by an automatic exposure algorithm to automatically calculate and/or manipulate camera exposure parameter values to capture an image in a predetermined manner. Through the exposure metering zone, it can be determined which part of the scene in the camera's field of view is considered to determine the automatic exposure settings. Determining the automatic exposure settings can then generally be defined as running any algorithm that automatically calculates and/or manipulates one or more camera exposure parameter values to capture an image in a predetermined manner. For example, for a given scene, there may be a predetermined optimal average brightness value, which the camera will attempt to achieve by adjusting one or more of the camera's exposure parameter values. For example, some automatic exposure algorithms calculate and/or manipulate exposure parameter values (e.g., camera gain) such that the average, median, or weighted value of the image brightness equals the predetermined optimal brightness value.

The exposure metering zone can be set to include the entire scene within the camera's field of view or only a portion of the scene within the camera's field of view. In the first case, the scene within the set exposure metering zone therefore corresponds to the scene within the camera's field of view. In the second case, the scene within the set exposure metering zone includes only a portion of the scene within the camera's field of view. In the first case, the automatic exposure setting is determined based on a portion of the scene within the set exposure metering zone, which therefore means determining the automatic exposure setting based on the entire scene within the camera's field of view (100% of the scene within the camera's field of view). This can also be referred to as "full-frame metering." In the second case, the exposure metering zone can be set to include only a portion of the scene within the camera's field of view (e.g., at least 10%, at least 20%, or at least 30%), such as a portion located at the center of the camera's field of view (this can be referred to as "center-point metering") or a portion of the scene outside the center of the camera's field of view (this can be referred to as "off-center metering"), for example, around a selected focus point outside the center. In this case, the automatic exposure setting is determined based on a portion of the scene within the set exposure metering zone, which means determining the automatic exposure setting based only on a portion of the scene within the camera's field of view. In one instance, a portion of the scene within the camera's field of view may include different regions, which can be weighted differently to determine the automatic exposure settings. In another instance, all regions of the scene or a portion of the scene may be weighted uniformly.

According to the method of the present invention, the scene in the exposure metering area includes at least a portion of a reagent test field on which an optical test strip of the sample is applied, at least a portion of a plurality of different color references of a color reference card, and at least a portion of a gray background field.

Setting the exposure metering zone and/or determining the automatic exposure settings can be initiated by user action or automatically, such as upon automatic detection of at least one object within the camera's field of view and/or a predetermined portion thereof. The user can manually set the exposure metering zone, for example, by pressing a button, or the mobile device's processor can be configured, such as through software programming, to set the exposure metering zone. Therefore, the setting of the exposure metering zone can be controllable, for example, controlled by the user or by software programming by the measurement application manufacturer. Conversely, the mobile device determining the automatic exposure settings based on the scene within the set exposure metering zone can be a device-specific process unknown to the measurement application manufacturer.

Exposure metering zones can be set statically or dynamically. For example, in a static setting, the exposure metering zone can be set to cover a predefined portion of the scene within the camera's field of view, such as a portion located at the center of the camera's field of view (an area of predefined size). Static settings specifically involve setting the exposure metering zone to determine automatic exposure settings before and after the mobile device tracks the position of the color reference card relative to the camera. For example, after setting the exposure metering zone to cover the center of the scene within the camera's field of view (an area of predefined size), the user can be guided to place the color reference card at the center of the camera's field of view. Dynamic settings specifically involve setting the exposure metering zone, where the mobile device first tracks the position of the color reference card relative to the camera, and when it is determined that the color reference card is appropriately visible within a portion of the camera's field of view, the exposure metering zone is set accordingly, and automatic exposure settings are determined based on the scene within the set exposure metering zone. A computer program (e.g., a measurement application) can be executed on the mobile device, wherein the computer program includes instructions to cause the mobile device to perform the step of setting the exposure metering zone. Once the exposure metering zone is set, automatic exposure settings can be determined automatically based on the scene within the set exposure metering zone. In this situation, computer programs (such as measurement applications) cannot directly adjust the exposure parameter values, but can only indirectly affect the automatic exposure settings by controlling the settings of the exposure metering area.

As described above, step c) includes capturing at least one image of the scene including step b) using a camera, wherein the determined automatic exposure settings of step b) are used.

As used herein, the term "image" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to a particular or customary meaning. The term may specifically refer to, but is not limited to, a set of spatially resolved optical data. Specifically, the term may refer to data recorded using a camera, such as multiple electronic readings from an imaging device, such as pixels from a camera chip.

As used herein, the term "capture at least one image" is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a particular or customary meaning. The term may specifically refer to, but is not limited to, one or more of imaging, image recording, image acquisition, and image capture. The term "capture at least one image" may include capturing a single image and/or multiple images, such as a series of images. For example, image capture may include the continuous recording of a series of images, such as a video or movie. The capture of at least one image may be initiated by user action or may be initiated automatically, for example, once at least one object is automatically detected to be present within the camera's field of view and/or a predetermined portion of the field of view. These automatic image acquisition techniques are known, for example, in the field of automatic barcode readers, such as those from automatic barcode reading applications. As an example, image capture may be performed by using a camera to capture an image stream or image "live," wherein one or more images are stored automatically or by user interaction (such as pressing a button), and one of these images is used as at least one image. Image acquisition may be supported by the processor of a mobile device, and image storage may be performed in the data storage device of the mobile device.

The at least one image includes the scene from step b). To capture the image, the determined automatic exposure settings from step b) are used. Since the brightness levels of the color reference card, particularly the brightness levels of the gray background field (within a certain range), control which automatic exposure settings are determined in step b) and then used to capture at least one image in step c), underexposure or overexposure of relevant portions of the captured image can be reduced or even prevented. This helps to obtain an image suitable for determining the concentration of the analyte in the sample.

The mobile device may include a display. The camera and display of the mobile device may both be positioned on the same side of the mobile device (in which case, the camera may be referred to as a front-facing camera) or positioned on opposite sides of the mobile device (in which case, the camera may be referred to as a rear-facing camera). Specifically, the camera may be a rear-facing camera. As an example, the mobile device may include a display, and the method of the present invention may include providing visual guidance on the display to position the camera relative to an object, which includes at least a portion of an optical test strip and/or at least a portion of a color reference card, for determining automatic exposure settings and/or for capturing at least one image. For example, the visual guidance includes one or more arrows, boxes, or lines indicating a preferred positioning of the camera relative to the object. As an example, the visual guidance includes an outline corresponding to the shape of the object superimposed on the display of the mobile device.

Providing visual guidance on a display to position a camera relative to an object on the display for determining exposure parameters and/or capturing at least one image may particularly involve providing visual guidance on the display to guide a user in positioning the camera such that the scene in the set exposure metering area includes at least a portion of a reagent test field on which an optical test strip of the sample is applied, at least a portion of a plurality of different color reference fields of a color reference card, and at least a portion of one or more gray background fields. The visual guidance may, for example, include an outline corresponding to the shape of at least a portion of the optical test strip and/or at least a portion of the color reference card superimposed on the display of the mobile device.

The determination of automatic exposure settings can be initiated automatically. Automatic determination of automatic exposure settings can be initiated, for example, upon determining that the outline of an object superimposed on the display covers the object. Specifically, the determination of automatic exposure settings can be initiated automatically once the presence of an object within the set exposure metering area and/or its specific location is automatically detected. The object may include at least a portion of an optical test strip and/or at least a portion of a color reference card.

Color reference cards may specifically include at least one position mark. Additionally or alternatively, test strips may include at least one position mark. As an example, the at least one position mark may be or may include an ArUco code, etc. Specifically, the at least one position mark may be located at at least one corner of the color reference card. As an example, the position mark may also be located at each corner of the color reference card (and the color card may potentially include additional position marks).

The mobile device is configured to detect and/or read one or more location markers, specifically by optical detection of the markers. Therefore, the mobile device is configured to detect and/or read the markers, specifically by optical detection of the markers, and optionally retrieve information from the markers, such as information about the type, nature, or orientation of the color reference card relative to the camera. Thus, the mobile device can, for example, automatically determine that the camera is in a defined position relative to the color reference card. If, based on at least one location marker being in a defined position relative to the color reference card, automatic exposure settings are determined to be automatically activated.

In one embodiment, the camera's position relative to a color reference card is determined based on at least one location marker, and the exposure metering zone is set according to the determined position. This is an example of dynamically setting the exposure metering zone. Specifically, the position of the reference card relative to the camera can be tracked, for example, by using at least one location marker (such as at least one ArUco marker), and an appropriate exposure metering zone can be set such that the scene within the exposure metering zone includes the color reference card used to determine the automatic exposure settings.

The color reference card may include at least one positioning element for positioning the optical test strip and/or the reagent test field. Specifically, the color reference card may include at least one window element through which the reagent test field is visible when the test strip is placed behind the color reference card. For example, the window element may be a cutout portion of the color reference card. The window element may be specifically configured to hold the optical test strip, and thus the reagent test field consists of the optical test strip, which is positioned relative to the color reference card. The reagent test field can be positioned specifically relative to the color reference card during the determination of camera exposure parameters and the capture of one or both of at least one image. This ensures optimal performance in terms of the accuracy of the achieved measurement results.

As described above, step c) of the method of the present invention includes capturing at least one image of the scene comprising step b) using a camera, wherein the determined automatic exposure settings of step b) are used. During the determination of the camera's exposure parameters and the capture of at least one image, or both, the camera may be in a defined position relative to a color reference card. Specifically, images may be captured using a camera and a color reference card in the same relative position as when the automatic exposure settings are determined.

The mobile device can automatically determine the presence and/or specific location of a color reference card, such as a set exposure metering zone, within the camera's field of view and/or a predetermined portion of the camera's field of view, based on location markers. Determining the automatic exposure settings can be initiated automatically, particularly once at least one object is automatically detected to be present within the camera's field of view or a predetermined area of the camera's field of view, the object comprising at least a portion of the optical test strip and/or at least a portion of the color reference card. Additionally or alternatively, capturing at least one image can be initiated automatically, particularly once at least one object is automatically detected to be present within the camera's field of view or a predetermined portion of the camera's field of view, the object comprising at least a portion of the optical test strip and/or at least a portion of the color reference card.

Preferably, the camera's exposure parameters and the lighting conditions during the capture of at least one image remain substantially constant. This ensures that the determined automatic exposure settings are actually suitable for capturing the image, thereby reducing or even preventing underexposure or overexposure of relevant portions of the captured image. In one embodiment, the illumination source of the mobile device, particularly the flash of the mobile device, can be used to illuminate the scene within the camera's field of view. Therefore, the determination of the automatic exposure settings for the camera and the lighting conditions during image capture can be primarily based on the illumination source of the mobile device, particularly the flash of the mobile device.

At least 5%, particularly at least 10% or at least 15%, of the scene within the set exposure metering area may include at least a portion of one or more gray background fields. In one instance, the scene within the set exposure metering area may include the entire color reference card. At least one image captured in step c) may substantially comprise the scene within the set exposure metering of step b). One or both of the above can help influence the automatic exposure settings by using a gray background field with defined grayscale values, thereby avoiding or at least reducing overexposure and/or underexposure of the image captured in step c). In one embodiment, the automatic exposure settings can therefore be influenced in such a way that the brightness of at least one color reference field differs from a case where a gray background field with defined grayscale values is replaced by a white field. In another embodiment, the automatic exposure settings can therefore be influenced in such a way that the brightness of at least one color reference field differs from a case where a gray background field with defined grayscale values is replaced by a black field.

As step d), the method may include determining at least one acceptability information item, wherein acceptability is indicated if each pixel or at least a predetermined group of pixels corresponding to a color reference field in at least one image exhibits a luminance value within acceptable limits, such as between 50 and 240, or between 80 and 220. The predetermined group of pixels may be determined dynamically within the camera's field of view based on at least one location marker. As used herein, the term "acceptability" is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a specific or customary meaning. The term may specifically relate to, but is not limited to, whether at least one captured image is permitted and/or rejected for characterization in determining analyte concentration. Thus, as an example, acceptability may be qualitatively or quantitatively determined by determining whether each pixel or at least a predetermined group of pixels corresponding to a color reference field in at least one image exhibits a luminance value within acceptable limits. The luminance value may be compared to one or more conditions. To give a simple example, a luminance value can be compared to one or more comparison values, reference values, or standard values, where the comparison can produce binary results such as "acceptable" or "unacceptable"/"unacceptable". As an example, comparison values and/or reference values can include minimum and maximum permissible luminance values. As an example, comparison values, reference values, and/or standard values can be derived experimentally or from boundary conditions (e.g., by analyzing the required accuracy in the measurement).

As used herein, the term "admissibility information item" is a broad term and will be given a meaning common and customary to those skilled in the art, but not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, an indication of information regarding admissibility. Specifically, an admissibility information item may refer to an indication of the admissibility of an analytical measurement result value determined from at least one image. As an example, the admissibility information item may be Boolean or numeric information, such as an indication of "admissible" or "non-admissible"/"unacceptable". Thus, as an example, in cases where the brightness value is below the minimum brightness value or above the maximum brightness value, for the purpose of determining the analytical measurement result value, the captured image may be determined as unacceptable.

In another aspect of the invention, a method for determining the concentration of an analyte in bodily fluids is disclosed. This method includes using a mobile device having at least one camera.

The method further includes:

i) Controlling the automatic exposure settings of the mobile device according to the invention, such as according to any of the embodiments disclosed above, and/or according to any of the embodiments disclosed in more detail below;

ii) Determine the concentration of the analyte in the sample by using at least one image of at least a portion of a reagent test field on which an optical test strip of the sample is applied and at least one image of at least a portion of a plurality of different color reference fields.

As used herein, the term "determining the concentration of an analyte in a body fluid," also known as "analytical measurement," is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a specific or customary meaning. The term specifically refers to, but is not limited to, the qualitative and/or quantitative determination of at least one analyte in any sample or aliquot of a body fluid. For example, body fluids may include one or more of blood, interstitial fluid, urine, saliva, or other types of body fluids. In one embodiment, the analyte is glucose and the body fluid is blood. Taking the result of concentration determination as an example, it may be the concentration of the analyte and/or the presence or absence of the analyte to be determined. Specifically, as an example, the determination may be a blood glucose measurement, and thus the result of the determination may be, for example, a blood glucose concentration. In particular, the result value of an analytical measurement can be determined by an analytical measurement.

Therefore, the term "analyte concentration value," which may also be referred to as "analytical measurement result value," or as used herein, "analytical measurement result value," is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, a numerical indication of the concentration of an analyte in a sample.

As an example, at least one analyte may be or may include one or more specific chemical compounds and/or other parameters. As an example, one or more analytes involved in metabolism, such as blood glucose, may be identified. Additionally or alternatively, other types of analytes or parameters, such as pH, may be identified.

Methods for determining the concentration of an analyte in bodily fluids also include the use of a moving device with at least one camera. Furthermore, the method includes the use of a color reference card and an optical test strip having a test field on which the sample is applied.

This method includes determining analyte concentration values based on color formation in a reagent test field. Therefore, this method can be an analytical measurement comprising inducing a test reaction between a test chemical substance and a bodily fluid sample or a portion thereof (such as at least one analyte), specifically a test reaction for analyte specificity, wherein the test reaction includes a color change in the reagent test field, which indicates the extent of the test reaction and/or the presence or concentration of the analyte. Color formation may include any change in at least one optical property of an optical test strip or, specifically, a reagent test field, which can be optically measured or determined using a camera. Specifically, the analytical measurement may be or may include a color formation reaction in the presence of at least one analyte to be determined. As used herein, the term "color formation reaction" is a broad term and will be given the common and customary meaning to those skilled in the art, and is not limited to a particular or customary meaning. The term may specifically refer to, but is not limited to, a chemical, biological, or physical reaction in which the color, particularly reflectance, of at least one element involved in the reaction changes as the reaction proceeds. Color formation can be detected by a mobile device, such as a processor of the mobile device, and can be quantitatively evaluated, such as by deriving at least one parameter from at least one image, which quantifies or characterizes the color formation of the reagent test field due to the presence of an analyte in a bodily fluid sample. As an example, one or more of the aforementioned color coordinates can be used. Therefore, the configuration of the mobile device, and particularly the processor of the mobile device, can determine the color change by identifying one or more color coordinate changes that occur due to the detection reaction.

The concentration value of at least one analyte is determined from the color formation of the reagent test field. For this purpose, at least one image may be used. As an example, the analyte concentration value may be a numerical indicator of the analytical measurement result, such as indicating the concentration of at least one analyte in the sample, for example, blood glucose concentration.

As an example, when capturing at least one image of at least a portion of the reagent test field, at least a portion of multiple different color reference fields of the color reference card and at least a portion of one or more gray background fields are located within the camera's field of view, and therefore, at least a portion of the color reference card is visible in at least one image of at least a portion of the reagent test field. As an example, an optical test strip may be placed on top of the color reference card, and/or the color reference card may include one or more windows (cutouts), wherein the color reference card having one or more windows is placed on top of the optical test strip such that the reagent test field is visible through the windows.

Specifically, using a color reference card allows for the correction of specific camera or device variations in at least one image of the color of the reagent testing area. Therefore, typically, the camera and/or mobile device apply one or more evaluation or pre-evaluation algorithms to the image without notifying the user, such as gamma correction, which must be taken into account when evaluating the image and determining at least one analyte concentration value. By using at least one color reference card with known optical properties, the mobile device can be configured for image correction and/or calibration; therefore, the internal procedures of the camera and/or mobile device must be considered when or before determining at least one analyte concentration value. As mentioned above, methods for determining the concentration of an analyte in bodily fluids include methods for controlling automatic exposure settings.

In another aspect of the invention, a mobile device is disclosed, having at least one camera and at least one display. The mobile device further has at least one processor. The mobile device is configured to perform at least steps b) and c) and optional step d) of the method for controlling automatic exposure settings according to the invention, such as according to any of the embodiments disclosed above, and/or according to any of the embodiments disclosed in more detail below.

The mobile device may be further configured to perform step ii) of the method for determining the concentration of an analyte in a sample according to the present invention, such as according to any of the embodiments disclosed above, and/or according to any of the embodiments disclosed in more detail below.

The term "processor" is a broad term and will be given a meaning common and customary to those skilled in the art, and is not limited to a specific or customary meaning. Specifically, the term may refer to, but is not limited to, any logic circuit configured to perform basic operations of a computer or system, and/or, in general, to means configured to perform computational or logical operations. In particular, a processor may be configured to process basic instructions that drive a mobile device, computer, or system. As an example, a processor may include at least one arithmetic logic unit (ALU), at least one floating-point unit (FPU) (e.g., a math coprocessor or a digital coprocessor), multiple recorders (specifically, recorders configured to provide operands to the ALU and store the results of operations), and memory (e.g., L1 and L2 caches). In particular, a processor may be a multi-core processor. Specifically, a processor may be or may include a central processing unit (CPU). Alternatively or concurrently, the processor may be or may include a microprocessor; therefore, specifically, the components of the processor may be contained within a single integrated circuit (IC) chip. Alternatively or concurrently, the processor may be or may include one or more application-specific integrated circuits (ASICs) and/or one or more field-programmable gate arrays (FPGAs), etc.

Specifically, the processor can be configured to perform one or more method steps of a method for controlling automatic exposure settings of a mobile device, such as through software programming. Specifically, the processor is configured to support setting an exposure metering zone and determining automatic exposure settings based on a scene within the set exposure metering zone, and to capture images, such as by prompting a user to capture an image and/or by detecting a color reference card in the field of view, and to automatically set the exposure metering zone and determine the automatic exposure settings based on a scene within the set exposure metering zone and/or automatically capture images. Furthermore, the processor can be configured to identify a color reference field on the captured image and determine its measured reference color value. The processor can be configured to assign known reference color values to corresponding measured color reference fields. Therefore, the processor can be configured to determine a relationship between the measured reference color values and corresponding known reference color values, for example, by fitting the measured reference color values to corresponding known reference color values. The processor can determine the relationship using a linear optimization method, such as a linear transformation of a color transformation matrix. Furthermore, the processor can be configured to derive at least one quality information item on the quality of the color reference card using this relationship.

Furthermore, the processor can be configured to perform and/or assist method steps for determining the concentration of an analyte in a body fluid, for example, through software programming. Specifically, the processor is configured to support the capture of at least one image using a camera of a mobile device, the at least one image including at least a portion of a reagent test field of an optical test strip with a sample applied, and at least a portion of multiple different color reference fields of a color reference card and at least a portion of one or more gray background fields. The processor is further configured to determine at least one analyte concentration value from color formation in the reagent test area, such as by controlling automatic exposure settings, converting one or more color coordinate changes resulting from the color formation reaction into at least one analyte concentration value. Specifically, the processor is configured to support one or more or all of steps b), c), and d) of the method for controlling automatic exposure settings and step ii) of the method for assisting in determining the concentration of an analyte in a body fluid. The processor is further configured to guide the user in providing the color reference card and the optical test strip with the test field having the sample applied, such as by providing user guidance, for example, in a visual or auditory form. The processor is further configured to assist in capturing at least one image, for example by automatically detecting an optical test bar or a portion thereof in the field of view and/or prompting the user to capture the image.

In another aspect of the invention, a kit is disclosed comprising at least one mobile device according to the invention, such as according to any of the embodiments disclosed above, and/or according to any of the embodiments disclosed in more detail below, further comprising an optical test strip having at least one reagent test field and at least one color reference card, the color reference card comprising a plurality of different color reference fields having known reference color values and one or more gray background fields having defined grayscale values. The term “kit” as used herein is a broad term and is to be given a common and customary meaning to those skilled in the art, and is not limited to a particular or customary meaning. The term may specifically refer to (but is not limited to) a combination of at least two items, as an example, which may be provided in combination in a package and may interact to achieve at least one common purpose.

In another aspect of the invention, a computer program comprising instructions, when executed by a mobile device having a camera, causing the processor of the mobile device to perform steps b) and c) (and optional step d) of a method for controlling automatic exposure settings according to any of the embodiments disclosed above and/or according to any of the embodiments disclosed in more detail below, and/or step ii) of a method for determining the concentration of an analyte in a body fluid.

In another aspect of the invention, a computer-readable storage medium comprising instructions which, when executed by a mobile device having a camera, cause the processor of the mobile device to perform steps b) and c) (and optional step d) of a method for controlling automatic exposure settings according to any of the embodiments disclosed above and/or according to any of the embodiments disclosed in more detail below, and/or step ii) of a method for determining the concentration of an analyte in a body fluid.

As used herein, the term "computer-readable storage medium" specifically refers to a non-transitory data storage device, such as a hardware storage medium on which computer-executable instructions are stored. This computer-readable data carrier or storage medium may specifically be or may include storage media such as random access memory (RAM) and/or read-only memory (ROM).

The computer program can also be embodied as a computer program product. As used herein, a computer program product may refer to a program that can be traded as a product. Products can typically be presented in any format, such as a thesis format, or on a computer-readable data carrier and/or on a computer-readable storage medium. Specifically, computer program products can be distributed across data networks.

The method and apparatus according to the invention enable analytical measurements using a wider variety of mobile device models. By using a quality-verified color reference card, accurate analytical measurements of analyte concentrations in bodily fluids can be provided even for a variety of different mobile devices.

The following summary describes, but does not exclude, more possible embodiments, the following of which are conceivable:

Example 1: A method for controlling the automatic exposure settings of a moving device (128) having at least one camera (130) when capturing at least one image of at least a portion of a color reference card (110) and at least one image of at least a portion of a reagent test field (120) on which an optical test strip (118) with a sample is applied, using a camera (130).

The method includes the following steps:

a) Provide a color reference card (110) and an optical test strip (118) with a test field (120) on which a sample is applied.

The color reference card (110) includes multiple distinct color reference fields (112) with known reference color values and one or more gray background fields (114) with defined grayscale values.

b) Set the exposure metering area and determine the automatic exposure settings based on the scene (126) in the set exposure metering area;

• The scene (126) in the exposure measurement area includes at least a portion of the reagent test field (120) on which the optical test strip (118) of the sample is applied, and at least a portion of the plurality of different color reference fields (112) of the color reference card (110) and at least a portion of the one or more gray background fields (114).

c) Capture at least one image of the scene (126) including step b) using a camera (120).

• The determined automatic exposure settings from step b) are used.

Example 2: According to the method described in the foregoing examples, the exposure metering area is set in a static or dynamic manner in step b).

Example 3: The method according to any of the foregoing embodiments, wherein the mobile device (128) includes a display (134), and the method further includes the following steps:

• Provide visual guidance on the display (134) to position the camera (130) relative to an object including at least a portion of an optical test strip (118) and/or at least a portion of a color reference card (110) for determining automatic exposure settings and/or for capturing at least one image.

Example 4: The method according to the foregoing embodiments, wherein visual guidance includes an outline (136) corresponding to the shape of an object superimposed on a display (134) of the mobile device (128).

Example 5: According to the method described in the foregoing examples, the automatic exposure setting is automatically activated, provided that the outline (136) of the object superimposed on the display (134) has been determined to cover the object.

Example 6: The method according to any of the preceding examples, wherein the color reference card and/or test strip includes at least one position mark (122).

Example 7: According to the method described in the foregoing embodiments, the automatic exposure setting is automatically activated, provided that the camera (130) is determined to be in a defined position relative to the color reference card (110) based on at least one position mark (122).

Example 8: The method according to any one of the preceding two embodiments, wherein the position of the camera (130) relative to the color reference card (122) is determined based on at least one position mark (122), and the exposure metering area is set according to the determined position.

Example 9: The method according to any of the preceding examples, wherein during determining one or both of automatic exposure settings for the camera (130) and capturing at least one image, the reagent test field (120) is in a defined position relative to the color reference card (110).

Example 10: The method according to any of the foregoing embodiments, wherein during the determination of automatic exposure settings for the camera (130) and the capture of one or both of at least one image, the camera (130) is in a defined position relative to the color reference card (110).

Example 11: The method according to any of the foregoing embodiments, wherein the automatic exposure setting is automatically activated, in particular once at least one object is automatically detected to be present in the camera's field of view and/or a predetermined area of the camera's field of view, the object comprising at least a portion of an optical test strip (118) and/or at least a portion of a color reference card (110).

Example 12: The method according to any of the foregoing embodiments, wherein capturing at least one image is automatically initiated, in particular once at least one object is automatically detected to be present in the camera's field of view and/or a predetermined area of the camera's field of view, the object comprising at least a portion of an optical test strip (118) and/or at least a portion of a color reference card (110).

Example 13: The method according to any of the foregoing embodiments, wherein the illumination remains substantially constant during the determination of automatic exposure settings for the camera (130) and the capture of at least one image.

Example 14: The method according to any of the foregoing embodiments, wherein the automatic exposure settings for the camera (130) are determined to include the lighting conditions during image capture and the lighting source primarily composed of the mobile device.

Example 15: The method according to any of the foregoing embodiments, wherein one or more gray background fields have defined gray values between 0% and 30% gray levels or between 70% and 100% gray levels.

Example 16: The method according to any of the preceding embodiments, wherein one or more gray background fields (114) having defined gray values cover at least 10% of the surface of the color reference card facing the camera.

Example 17: The method according to any of the preceding embodiments, wherein at least 5%, particularly at least 10% or at least 15%, of the scene in the set exposure metering area includes at least a portion of one or more gray background fields (114).

Example 18: The method according to any of the preceding examples, wherein the scene (126) in the set exposure metering area includes the entire color reference card (110).

Example 19: The method according to any of the preceding embodiments, wherein at least one image captured in step c) substantially comprises the scene (126) in the exposure metering set in step b).

Example 20: The method according to any of the foregoing embodiments, wherein the method further includes:

d) Determine at least one acceptability information item, wherein the acceptability information item indicates acceptability if each pixel or at least a predetermined group of pixels corresponding to a color reference field (112) in at least one image exhibits a luminance value within an acceptable limit, such as between 50 and 240, or between 80 and 220.

Example 21: The method according to any one of the foregoing embodiments, wherein the method further includes:

e) The concentration of the analyte in the sample is determined by using at least one image of at least a portion of a reagent test field (120) on which the optical test strip (118) of the sample is applied and at least one image of at least a portion of a plurality of different color reference fields (112).

Example 22: A method for determining the concentration of an analyte in a sample using a moving device (128) having at least one camera (130).

The method includes the following steps:

i) When capturing at least one image of at least a portion of a color reference card (110) and at least one image of at least a portion of a reagent test field (120) to which the optical test strip (118) of the sample is applied using a camera (130), the automatic exposure settings of the moving device (128) according to any of the foregoing embodiments are controlled.

ii) The concentration of the analyte in the sample is determined by using at least one image of at least a portion of a reagent test field (120) on which the optical test strip (118) of the sample is applied and at least one image of at least a portion of a plurality of different color reference fields (112).

Example 23: The method according to any one of the preceding two examples, wherein the analyte is glucose and the body fluid is blood.

Example 24: A mobile device (128) having at least one camera (130) and at least one display (134), the mobile device (128) being configured to perform at least steps b) and c) and optionally step d) of the method for controlling automatic exposure settings according to any one of Examples 1 to 21 above.

Example 25: A mobile device according to the foregoing embodiments, configured to perform step e) of the method for controlling automatic exposure settings as described in Example 21 or 23, or step ii) of the method for determining the concentration of an analyte in a sample as described in Example 22 or 23.

Example 26: A kit for determining the concentration of an analyte in body fluids, the kit comprising:

-The mobile device according to embodiment 24 or 25

- At least one optical test strip (118) having at least one reagent test field (120),

- At least one color reference card (110), wherein the color reference card (110) includes a plurality of different color reference fields (112) having known reference color values and one or more gray background fields (114) having defined gray values.

Example 27: A computer program including instructions that, when executed by a mobile device (128) having a camera (130), cause the mobile device (128) to perform at least steps b) and c) and optionally steps d) and/or e) and ii) of the method according to any of the foregoing method embodiments.

Example 28: A computer-readable storage medium, particularly a non-transitory storage medium, comprising instructions which, when executed by a mobile device (128) having a camera (130), cause the mobile device (128) to perform at least steps b) and c) and optionally steps d) and/or e) and ii) of the method according to any of the foregoing method embodiments.

Attached Figure Description

Further optional features and embodiments will be disclosed in the details of the following embodiments, preferably in conjunction with the dependent claims. Individual optional features may be implemented individually or in any feasible combination, as would be apparent to those skilled in the art. The scope of the invention is not limited to the preferred embodiments. Embodiments are depicted graphically. In these figures, reference numerals that are the same are used to refer to elements that are the same or functionally similar.

In these attached figures:

Figure 1 shows a plan view of the color reference card;

Figure 2 illustrates an embodiment of the kit, which includes a mobile device, a color reference card, and optical test strips.

Figure 3 illustrates the scenario where automatic exposure settings are determined and an image is captured based on the scene within the set exposure metering zone.

Figure 4 shows a flowchart of an embodiment of the method for controlling automatic exposure settings; and

Figure 5 shows a flowchart of an embodiment of a method for determining the concentration of at least one analyte in body fluids.

Detailed Implementation

Figure 1 shows a plan view of an exemplary embodiment of the color reference card 110. The color reference card 110 includes a plurality of color reference fields 112 having known reference color values. The color reference fields 112 may be configured on the surface of the color reference card 110, such as on the surface of a substrate of the color reference card 110. In particular, the color reference fields 112 may be evenly distributed on the surface of the color reference card 110, specifically, in such a way that the plurality of color reference fields 112 may be distributed across the entire surface of the color reference card 110. As an example, the color reference fields 112 may be configured in a matrix pattern, such as a rectangular matrix pattern. However, the color reference fields 112 may also be configured in other ways, such as being configured to be separated from each other. The color reference card 110 further includes one or more gray background fields 114 surrounding the color reference fields 112 and/or framing the color reference card. The color reference fields 112 and the gray background fields 114 may not overlap each other.

The color reference card 110 may further include at least one window 116. Thus, when the color reference card 110 is placed on top of the optical test strip 118, at least one optical test strip 118 or a portion thereof can be seen through the window 116. Specifically, at least one reagent test field 120 included in the optical test strip 118 can be seen through the window 116 of the color reference card 110. As another example, the color reference card 110 may include an optical test strip 118 having at least one reagent test field 120, specifically in a manner that makes at least one reagent test field 120 accessible and visible.

Furthermore, the color reference card 110 may include at least one position mark 122. This position mark 122 may specifically be an ArUco code. In FIG. 1, the position mark 122 may specifically include one or more ArUco codes, such as at the corners of a rectangular matrix including the color reference fields 112. Therefore, the position mark 122 may typically be arranged at at least one corner 124 of the color reference card 110. For example, at least one position mark 122 may be arranged at each corner 124 of the color reference card 110, specifically in such a way that the position mark 122 is visible simultaneously with multiple color reference fields 112. Furthermore, the position mark 122 may include information regarding the orientation of the color reference card 110.

Figure 2 shows a perspective view of an exemplary embodiment of the kit. The kit includes at least one moving device 128 and at least one color reference card 110. Furthermore, the kit includes at least one optical test strip 118.

Mobile device 128 may be or may include at least one of a mobile phone, smartphone, tablet computer, etc. Furthermore, mobile device 128 has at least one camera 130. The camera 130 of mobile device 128 is configured to record images, specifically color images. Therefore, camera 130 may be a color camera and may include sensors for at least three colors, such as at least one color sensor for R, G, and B colors.

Furthermore, the mobile device 128 may include at least one processor 132. The processor 132 may be configured to specifically execute one or more of the method steps b), c), and d) of controlling automatic exposure settings via software programming. Additionally, the processor 132 is configured to support step ii) of the method for determining the concentration of the analyte. Figures 4 and 5 respectively present exemplary embodiments of the above-described method, which will be described in detail below. Therefore, reference can be made to the description of Figures 4 and 5.

Processor 132 is configured to specifically support the setting of an exposure metering zone and determine automatic exposure settings based on scene 126 within the set exposure metering zone. In the illustrated embodiment, scene 126 within the set exposure metering zone includes a color reference card and a reagent test field. Processor 132 is configured to specifically capture at least one image including scene 126. Specifically, processor 132 may prompt a user of mobile device 128 to capture an image. Additionally or alternatively, processor 132 may be configured to automatically capture an image of color reference card 110, specifically when color reference card 110 is within the field of view.

Color reference card 110 has been described above (see Figure 1). Color reference card 110 includes a plurality of color reference fields 112 having known reference color values. Furthermore, color reference card 110 may include at least one window 116. Thus, optical test strip 118 can be seen through window 116 of color reference card 110, specifically when color reference card 110 can be placed on top of optical test strip 118, making both color reference card 110 and optical test strip 118 visible in an image captured by camera 130 of moving device 128. Specifically, at least one reagent test area 120 of optical test strip 118 can be seen through window 116 of color reference card 110.

The color reference card 110 may further include at least one position mark 122. The position mark 122 may be disposed on at least one surface of the color reference card 110 such that the camera 130 of the mobile device 128 can detect the mark 122. At least one mark 122 may be used to identify the color reference card 110. Specifically, the processor 132 of the mobile device 128 is configured to detect the position mark 122 within the field of view of the camera 130.

Figure 3 illustrates the process of determining automatic exposure settings and capturing an image. In this embodiment, visual guidance is provided on the display in the form of an outline 136 of a color reference card superimposed on the display 134 of the mobile device 128 to guide the user in positioning the camera such that the scene corresponding to outline 136 in the set exposure metering area includes at least a portion of a reagent test field on which an optical test strip of the sample is applied, at least a portion of a plurality of different color reference fields, and at least a portion of one or more gray background fields. In the illustrated example, the scene in the set exposure metering area includes the entire color reference card.

Determining the automatic exposure settings and capturing an image can be initiated automatically. Automatic determination of the automatic exposure settings can, for example, be initiated automatically based on the detection that the color reference card is within the set exposure metering area using position marker 122. Similarly, an image can then be captured automatically using the determined automatic exposure settings.

Figure 4 shows a flowchart of an exemplary embodiment of the method for controlling the automatic exposure setting 138 of the mobile device.

The method includes:

a) (indicated by reference numeral 142) provides a color reference card and an optical test strip with a test field on which the sample is applied.

-The color reference card includes multiple different color reference fields with known reference color values and one or more gray background fields with defined grayscale values.

b) (indicated by reference numeral 144) Set the exposure metering area and determine the automatic exposure settings based on the scene within the set exposure metering area;

-The scene set in the exposure metering includes at least a portion of the reagent test field on which the optical test strip of the sample is applied, at least a portion of the plurality of different color reference fields of the color reference card, and at least a portion of the one or more gray background fields, and

c) (indicated by reference numeral 146) capturing images of the scene including step b) using a camera.

-The determined automatic exposure settings from step b) are used.

This method may include additional steps not listed.

In step a), a color reference card 110 and an optical test strip 118 having a test field on which a sample is applied are provided. The processor 132 is configured to guide the user in providing the color reference card and optical test strip by providing user guidance, for example, in a visual or auditory form.

In step b), an exposure metering zone is set, and an automatic exposure setting is determined based on scene 126 within the set exposure metering zone. For example, processor 132 is configured to prompt the user to place a color reference card in the camera's field of view, or the position of the color reference card 110 can be tracked by a moving device via position marker 122. As an example, processor 132 is configured to detect the color reference card 110 in the field of view, and further determine the automatic exposure setting when a color reference card with position marker 122 is detected in the set exposure metering zone.

In step c), an image is captured. The capture of at least one image may be initiated by a user action or may be initiated automatically, for example, once a color reference card is detected in the field of view of camera 130 based on location marker 122. Image capture may be supported by processor 132 of mobile device 128, and image storage may be performed in the data storage device of mobile device. The at least one image includes the scene from step b). To capture the image, the determined automatic exposure settings from step b) are used.

In one experiment, two color reference cards similar to the color reference card shown in Figure 1 were compared, but with different grayscale values against a gray background. Automatic exposure settings were determined based on each color reference card placed in the exposure metering area, and then images of each color reference card were captured separately using the determined automatic exposure settings.

The table below shows how the brightness levels of the gray background field affect the detection brightness of an exemplary color reference field on a color reference card by influencing the automatic exposure settings.

grayscale of a gray background field Brightness (r, g, b) of the color reference field Light gray (138/155/36) Average of 20 images Dark gray (148/168/40) Average of 13 images

Compared to a color reference card with a darker gray background field, the exemplary color reference field has lower brightness when using a color reference card with a light gray background field. Even brighter or darker gray background fields can be used to more strongly control the exposure level to the desired level. When imaged with a color reference card, this can help obtain an image suitable for determining the concentration of the analyte in the sample for the test field applied to the test strip (e.g., by avoiding overexposure or underexposure of the test field or related field of the color reference card required for image correction when determining analyte concentration).

Figure 5 shows a flowchart of an exemplary embodiment of a method for determining the concentration of an analyte in a sample using a moving device 128 having at least one camera 130.

The method includes:

i) (denoted by reference numeral 138) When at least one image of at least a portion of a color reference card (110) and at least one image of at least a portion of a reagent test field (120) on which the optical test strip (118) of the sample is applied are captured by a camera (130), the automatic exposure settings of the moving device as described above are controlled.

(ii) (denoted by reference numeral 148) The concentration of the analyte in the sample is determined by using at least one image of at least a portion of a reagent test field (120) on which an optical test strip (118) to which the sample is applied and at least one image of at least a portion of a plurality of different color reference fields (112).

Regarding step i), refer to the method for controlling the automatic exposure setting 138 as described above. In step ii), for example, the glucose concentration in the blood sample applied to the test strip can be determined from the color formation of the reagent test field using at least one captured image. The moving device can be configured for image correction and/or calibration using intensity values determined from one or more color reference field cards with known optical properties; therefore, the internal procedures of the camera and/or moving device must be considered when or before determining at least one analyte concentration value.

Symbol Explanation

110 Color Reference Card

112 Color Reference Field

114 Gray background field

116 Window

118 Optical Test Strips

120 Reagent Testing Field

122 Location Marker

124 angles

126 Scene

128 Mobile devices

130 Camera

132 Processor

134 Monitor

136 Outline

138 Automatic exposure settings for controlling the moving device

140 Provides a color reference card (110) and optical test strips.

142 Set the exposure metering area and confirm the automatic exposure settings.

144 Capture Image

148. Determine the concentration of the analyte.

Claims (15)

1. A method for controlling an automatic exposure setting when capturing at least one image of at least a portion of a color reference card (110) and at least a portion of a reagent test field (120) to which an optical test strip (118) with a sample is applied, the automatic exposure setting being an automatic exposure setting of a moving device (128) having at least one camera (130), The method includes the following steps: a) Provides a color reference card (110) and an optical test strip (118), the optical test strip having a test field (120) on which the sample is applied. The color reference card (110) includes multiple distinct color reference fields (112) with known reference color values and one or more gray background fields (114) with defined grayscale values. b) Set the exposure metering area, and determine the automatic exposure settings based on the scene (126) within the set exposure metering area. The scene (126) in the exposure metering area wherein the setting includes at least a portion of the reagent test field (120) on which the optical test strip (118) of the sample is applied, at least a portion of the plurality of different color reference fields (112) of the color reference card (110), and at least a portion of the one or more gray background fields (114). c) By using the camera (120), capture at least one image of the scene (126) including step b). The determined automatic exposure settings from step b) are used. 2. The method according to any one of the preceding claims, wherein the mobile device (128) includes a display (134), and the method further includes the following steps: The display (134) provides visual guidance for positioning the camera (130) relative to an object, which includes at least a portion of the optical test strip (118) and/or at least a portion of the color reference card (110), for determining the automatic exposure settings and/or for capturing the at least one image. 3. The method according to any one of the preceding claims, wherein the color reference card and/or the test strip includes at least one position mark (122). 4. The method according to the preceding claims, wherein if it is determined that the camera (130) is in a defined position relative to the color reference card (110) based on the at least one position mark (122), the automatic exposure setting is automatically activated. 5. The method according to any one of the preceding two claims, wherein the camera (130) is determined based on the position of the at least one position mark (122) relative to the color reference card (110), and the exposure metering zone is set based on the determined position. 6. The method according to any one of the preceding claims, wherein during determining the automatic exposure settings for the camera (130) and capturing one or both of the at least one image, the reagent test field (120) is in a defined position relative to the color reference card (110). 7. The method according to any one of the preceding claims, wherein determining the automatic exposure settings and/or capturing the at least one image is automatically initiated, particularly once at least one object is automatically detected to be present in the field of view of the camera and/or within a predetermined area of the field of view of the camera, the object comprising at least a portion of the optical test strip (118) and/or at least a portion of the color reference card (110). 8. The method according to any one of the preceding claims, wherein at least 5%, particularly at least 10% or at least 15% of the scene in the exposure metering area of the setting consists of at least a portion of the one or more gray background fields (114). 9. The method according to any one of the preceding claims, wherein the scene (126) in the exposure metering area set therein includes the entire color reference card (110). 10. The method according to any one of the preceding claims, wherein the method further comprises: d) Determine at least one acceptability information item, wherein the acceptability information item indicates acceptability if each pixel or at least a predetermined group of pixels corresponding to the color reference field (112) in the at least one image exhibits a brightness value within an acceptable limit, such as between 50 and 240, or between 80 and 220. 11. A method for determining the concentration of an analyte in a sample by using a moving device (128) having at least one camera (130). The method includes the following steps: i) When capturing at least one image of at least a portion of a color reference card (110) and at least a portion of a reagent test field (120) with an optical test strip (118) to which the sample is applied using the camera (130), the automatic exposure settings of the moving device (128) are controlled according to any of the preceding claims. ii) The concentration of the analyte in the sample is determined by using at least one image of at least a portion of the reagent test field (120) on which the optical test strip (118) of the sample is applied and at least a portion of the plurality of different color reference fields (112). 12. A mobile device (128) having at least one camera (130) and at least one display (134), said mobile device (128) being configured to perform at least steps b) and c) and optionally step d) of the method for controlling automatic exposure settings according to any one of claims 1 to 11. 13. A kit for determining the concentration of an analyte in body fluids, the kit comprising: - The mobile device according to claim 11 or 12, - At least one optical test strip (118) having at least one reagent test field (120), - At least one color reference card (110), wherein the color reference card (110) includes a plurality of different color reference fields (112) having known reference color values and one or more gray background fields (114) having defined gray values. 14. A computer program comprising instructions which, when executed by a mobile device (128) having a camera (130), cause the mobile device (128) to perform at least steps b) and c) and optionally steps d) and/or ii) of the method according to any one of the preceding method claims. 15. A computer-readable storage medium, particularly a non-transitory storage medium, comprising instructions which, when executed by a mobile device (128) having a camera (130), cause the mobile device (128) to perform at least steps b) and c) and optionally steps d) and/or ii) of the method according to any one of the preceding method claims.