JP2000175869A - Fundus image processing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a fundus image processing apparatus capable of automatically performing up / down or 90 ° rotation of a fundus photograph or discrimination between front and back. A fundus image processing apparatus for digitizing a fundus photograph provided with a cutout image portion for clarifying a front / back side with a video camera, wherein the fundus photograph read by the video camera is rotated up, down, or 90 degrees. A fundus image processing apparatus having a central processing unit 212 for distinguishing front and back.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus image processing apparatus for electronically inputting and processing a fundus image.

[0002]

2. Description of the Related Art In recent years, conversion of medical images from silver halide photographs to electronic images has been promoted. The ophthalmology field is no exception, especially in fields where the benefits of electronic filing can be used, such as regular medical examinations, and when investigating the three-dimensional shape of the fundus.
Electronic images are gradually being adopted from fields that are difficult to realize without electrophotography.

When introducing an electronic image, at present, an electronic image is inferior to a silver halide photograph in an apparatus having an economically acceptable price. In this regard, for a while, in a field requiring precise diagnosis, a method in which a film once photographed by silver halide photography is made, and a silver halide photograph is converted into an electronic image at the stage of storing this film is considered.

[0004] Further, in fields that do not require much precision such as mass examinations, it is conceivable that the fundus image can be directly obtained as an electronic image. However, it is attempted to make a search comparison including an old image by making use of the characteristic of the electronic image. In this case, an old image is often present on a silver halide film for the time being, and it is conceivable that the old image is converted into an electronic image using a video camera or a scanner using a linear sensor and used.

[0005]

It is considered that the operation of electronically converting a silver halide photograph will continue as described above. In such a case, it is necessary to judge the front and back of the slide film, the top and bottom, and the distinction between the left and right eyes. The operation must be performed by the operator, which is troublesome, and sometimes an erroneous image is input.

Accordingly, a first object of the present invention is to provide a fundus image processing apparatus capable of automatically performing vertical or horizontal rotation of a fundus photograph by 90 ° or discrimination between front and back.

A second object of the present invention is to automatically or vertically rotate a fundus photograph or discriminate between the front and back of a fundus photograph, and to rotate the fundus photograph vertically or by 90 ° or input the wrong side. It is another object of the present invention to provide a fundus image processing apparatus capable of issuing a warning to an operator.

Further, a third object of the present invention is to automatically or vertically rotate the fundus photograph or discriminate between the front and back of the fundus photograph, and to perform the rotation of the fundus photograph vertically or by 90 ° or wrong input of the front and back. Another object of the present invention is to provide a fundus image processing device that converts image position data read by a photographic image reading device into regular image position data.

[0009]

In order to achieve the first object, a first aspect of the present invention is a fundus image processing apparatus for digitizing a fundus photograph with a photographic image reading apparatus. The fundus image processing apparatus may further include an image arrangement determining unit configured to determine whether the fundus photograph is rotated up, down, 90 °, or front or back.

According to a second aspect of the present invention, in order to achieve the second object, if the orientation of the image determined by the image arrangement determining unit is not a normal orientation, a warning unit for warning that effect or A display for displaying that the orientation is not correct is provided.

According to a third aspect of the present invention, in order to achieve the third object, when the fundus photograph is read by the photographic image reading device, the fundus photograph is rotated up and down, or rotated by 90 °, or input incorrectly. In this case, the apparatus further comprises a coordinate conversion means for rotating the image position data read by the photographic image reading device up and down or 90 ° or converting the front and back coordinates into the coordinates of the image direction data in the correct direction.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a main part of an optical system of a fundus camera GK (imaging device) for photographing (imaging) a fundus image to be processed in the present invention, and illuminates the fundus of the eye to be examined. And an observation system B for observing or photographing the fundus of the eye to be examined. Illumination system A Illumination system A is observation light source 1
Having. The luminous flux emitted from the observation light source 1 passes through a condenser lens 2 and an infrared filter 3 that cuts visible light and transmits only infrared light, and then is reflected by an oblique half mirror 4 to form a ring-shaped aperture 5. Light up.

The illumination system A is provided with a photographing light source 6. The light from the photographing light source 6 passes through the condenser lens 7 and the oblique half mirror 4 and
To illuminate.

The light transmitted through these ring-shaped diaphragms 5 is
A perforated mirror obliquely provided on the optical axis of the objective lens 10 via the relay lens 36, the oblique mirror 37, and the relay lens 8.
The light reaches the objective lens 9 and is reflected by the perforated mirror 9 in the direction of the objective lens 10 to illuminate the fundus of the eye 11 through the objective lens 10. The light beam reflected by the fundus of the observation and imaging system B subject's eye 11 passes through the objective lens 10 and the opening of the perforated mirror 9, travels along the optical axis of the objective lens 10, and is provided on this optical axis. The fundus image of the eye to be examined is formed on the surface of the film 14 by the focusing lens 12 and the imaging lens 13.

A mirror 15 is disposed in front of the film 14 so as to be retractable. The mirror 15 is arranged at a position indicated by a solid line during observation and retracted to a position indicated by a broken line during photographing.

Therefore, the light beam from the fundus during observation is reflected upward by the mirror 15 and a fundus image is formed on the field lens 16. The fundus image formed on the field lens is relayed on the photoelectric surface of the infrared light imaging tube 19 by the oblique mirror 17 and the relay lens 18 to form an image. Imaging tube
The electric signal from 19 displays a fundus image as a visible image on both sides of the monitor television 20.

A field stop 21 is provided immediately before the film 14 to regulate the shape of the field of view on the film surface. An example of the field stop 21 is shown in FIG. This field stop has a circular opening 100 and a notch 101 in a part thereof. Normally, the examiner determines the front and back of the photograph based on the direction of the notch 101.

FIGS. 3 (a) and 3 (b) show the right eye (a) and the left eye, respectively.
An example of the fundus image G of (b) is shown. This fundus image G is
When the angle of view is 45 °, which is often used for mass screenings, the nipple
Most commonly, the nose-side imaging range L2 is 1.5 times that of the 81 system L1. At this time, the visual field center O includes the fovea 82 and is located between the dark macula 80, which has relatively low reflectance at the fundus, and the optic disc 81, which has the highest reflectance at the fundus and is therefore the brightest. The fundus image G includes a circular image portion 100 ′ corresponding to the circular opening 100 of the field stop 21 and a notch of the field stop 21.
It has a cutout image portion 101 ′ corresponding to 101.

When a fundus image having the above characteristics is digitized, a histogram of the number of pixels with respect to the light intensity is as shown in FIG.

Here, the section A of the brightness corresponds to the portion covered by the mask in FIG. 2, and the section C corresponds to a very bright portion of the optic disc 81. Section B corresponds to another portion of the fundus having intermediate brightness.

Because of these features, it is easy to distinguish a portion covered by the field stop 21 from a portion where an image exists, and the direction of the notch 101 can be determined by image processing. Also, if the center O of the opening 100 of the field stop 21 is known, which side of the optic disc 81 is present, or by determining which side of the left or right is brighter,
It is possible to determine whether the images are left and right eyes.

An example of an electronic filing apparatus FS for fundus images taking such points into consideration will be described with reference to FIG.

FIG. 5 illustrates an example in which a video camera is used to input an image from a slide, and the microcomputer is used as a controller for image processing and filing.

The filing apparatus includes a base 201, a lighting device (light box) 202 mounted on the base 201,
It has a video camera 205. The illumination device 202 is provided with a holder 301 for holding a slide original image 203, and captures an image of the slide original image held by the holder 301 via a lens 204 of a video camera 205.

FIG. 10 shows an example of the holder 301. This example is 3
This is an example of a case where a 5 mm film is held naked, and is constituted by four pins 302 provided on a light box. By narrowing the distance b between the pins in the film longitudinal direction with respect to the film width a, it is possible to prevent the film from being erroneously placed in a direction rotated by 90 °. If necessary, a good flatness of the film can be maintained by using a cover glass or a holding frame.

FIG. 11 shows an example of the original image mounted on the slide frame S. The original image mounted by the step portion 304 and the pin 303 is held at a predetermined position.

In the above method, the original image is always kept at a fixed position, the trouble of performing alignment every time the original image is exchanged is eliminated, and at the same time, the conditions for judging whether the front, back, top, bottom, left and right are correctly placed are determined. One of them is that the original picture can only be placed in approximately 90 degrees of rotation.

The image signal is input to a frame memory 206 having an image display 207 for displaying its contents, and is digitized / digitized. Frame memory 206
Are processed by the central processing unit 212 having the operation terminal 217. As will be described later, the central processing unit 212 functions as an image arrangement determining unit, a coordinate converting unit, or a unit for determining the right, left, up, down, front and back of the fundus image, and includes a display 214, a keyboard 215, and a mouse 216 (pointing device). And the like.

The central processing unit 212 further includes a disk unit 208 for storing programs of the central processing unit 212 and temporary image data, and an optical disk or a magneto-optical disk for finally storing image data and a database. And the like are connected. The central processing unit 212 has a general-purpose interface 210 for inputting / outputting various signals from / to the outside, a communication interface 211 for performing communication with the outside, and a memory for carrying a small amount of image data and a database. Card device
213, a warning buzzer B (warning means) and the like are connected.

Next, the operation of such a configuration will be described.

The image of the original slide 203 captured by the illumination device 202 is captured by the lens 204 and the video camera 205 and is temporarily stored in the frame memory 206. Here, the front and back of the slide are first determined. Note that the video camera 205 and the frame memory 206 constitute a photographic image reading device.

The above-described processing such as front / back determination is performed by a frame memory.
The image on 206 is performed by central processing unit 212.

Since it is known that the aperture 100 of the field stop 21 is circular, scanning is performed in the direction indicated by the arrow in FIG. 6A, and the brightness suddenly increases as indicated by the point t in FIG. 6B. It can be determined that the changed position is the beginning of the opening 100.

First, scanning is performed in the direction of, and upper and lower edges a and a 'are found. At this time, if the distance between a and a 'is too small, there is a possibility that a position largely shifted left or right of the opening 100 has been scanned. Then, a position having a large distance between the points 'a' and 'a' is scanned in the direction between the upper and lower positions of a and a ', and points b and b' are similarly obtained.

Here, the position of the center point O of the opening is obtained from the coordinates of the points a, a ', b and b'. Also, b, b at this time
The distance between 'is the diameter of the opening.

Next, a range of (radius) × (predetermined constant k) from the center point O to the radius r of the opening 100 or more, ie, FIG.
The average brightness in the range is determined for each quadrant. The average brightness of the above quadrant having the notch 101 is brighter than that of the other quadrants.

In the example of FIG. 7, that of the first quadrant is brighter than that of the other quadrants. Therefore, it can be understood that the notch 101 exists in the quadrant having the highest average brightness by performing the above operation.

Since the quadrant having the notch 101, the shape, and the like are determined for each manufacturer model, if this information is set in advance, the input image can be correctly compared with this information so that the front, back, top, bottom, left, and right sides are correct. You can know if it is input. The above-mentioned constant k is desirably a constant such that all the cutouts fall within the range of r × k with respect to r, and can also be determined from the cutout information set here.

If the orientation determined in this way is not a proper one, the apparatus issues a warning with a buzzer B and causes the display 207 to indicate that the orientation is not regular.

Next, determination of the left and right eyes will be described.

As shown in FIG. 8, a fundus photograph in a general mass examination or the like is shown in FIG. 8 (the subject's right eye) and FIG. 9) (the subject's left eye).
The brightest nipple at the fundus on the nose side of the visual field center O as shown in 8
There is one. Therefore, in such a fundus photograph, the total light amount of each of the left and right except for the notch 101 of the field stop is obtained at the center of the field of view, and it is possible to know which of the right and left eyes by comparing the total light amounts. it can. In order to obtain the total light amount, the brightness of all the pixels in the above range may be accumulated, and for the sake of simplicity at high speed, the number of pixels to be accumulated in a range where a sufficient sampling point can be obtained in the optic disc 81 is calculated. It is possible to sample with a spatula.

In the case of handling an unmounted original 203 'as shown in FIG. 1, if it is known from the above operation that the notch is located in which quadrant, the current original 203' is displayed. You can determine the direction in which it is placed. This is because they cannot be misplaced in the 90 ° direction.

As shown in FIG. 12, the mounted original 203
When ´ is used, it may not be possible to judge the front and back with this alone. That is, since the outer shape of the mounting frame or the slide frame S is square, when the frame is turned upside down around the diagonal of the frame, a notch is formed in the direction of 45 ° from the horizontal direction as in many fundus photographs. It is not possible to determine the front and back sides of an image that has it.

In this case, for example, the front and back can be determined by the following operation. That is, as shown in FIGS. 13 (a) and 13 (b), if sampling for determination of the left and right eyes is divided not only to the left and right but also to the top and bottom, and divided into four quadrants I to IV,
When the nipple and macula are located substantially horizontally as in (a) [hereinafter, (I) to (IV) are the brightness of each quadrant], | [(I) + (IV)] − [( II) + (III)] |> |
[(I) + (II)]-[(III) + (IV)] | As shown in FIG. 13, when each is positioned substantially vertically, | [(I) + (IV)]-[(II) + (III)] | <|
[(I) + (II)]-[(III) + (IV)] |, so in this case, it can be determined in which direction it is placed.

Finally, the image data includes the left and right eye determination results obtained as described above and the name and age of the subject obtained from the operator using the keyboard 215 or from an external database using the communication interface 211. Along with personal information such as gender and the like, and stored in a large-capacity storage device 209 such as an optical disk.

When a plurality of images are input to the same subject, and a selection is made from among them, the images can be temporarily stored in a disk device. Storage media such as optical disks or magneto-optical disks
Since it is exchangeable and can usually store images for several hundreds or more people, it can be used as a storage medium per day for data transfer between an examination center and an imaging place in the case of group examination. However, it is wasteful to use such a case that a very small number of image data necessary for one diagnosis of one patient needs to be moved in a hospital. In such a case, a memory card having an appropriate capacity can be used.

The filing of image data is performed according to a program of the central processing unit 212 stored in the disk device 208. At this time, the handling of the data such as the personal information of the subject and the image data, in particular, the method of combining the image data is described in “(1) The subject data and the image data are edited and stored in one file. (3) Store the subject data and the image data as completely separate files (3) Register only the subject information file in the database and describe the file name of the image data in the subject information file . "

In each case, the left eye / right eye information is
Specific examples of each example, which are necessary for later retrieval, are shown below. "Method (1); subject information, left eye, and right eye are combined in this order. Method (2); file name has left and right eye information. Method (3); left eye , A correspondence table between the right eye and the image file is created in the file of the subject information. "

The filing device and its control software can be easily realized by combining a personal computer with some hardware options and database software. Application Example of Embodiment Image input may be direct input from a fundus camera or the like. At this time, there is no need to make a front / back determination, and only the left / right eye determination is used. As shown in FIG. 4, a light intensity histogram is obtained from the image data, a slice level for selecting only the field stop 77 or the optic disc is determined, and the front / back and left / right eyes can be determined by feature extraction. When the device detects that the original image is placed in an inappropriate orientation, it issues a warning and at the same time converts the captured image to the correct orientation by performing coordinate transformation on the captured image. Can be. When performing this coordinate conversion, a warning is not necessarily required. ) For extremely poor quality original images such as cataract eyes, the result of automatic judgment can be overridden (manual correction) by input from the keyboard. The following method can be used to determine whether the original image placed in the slide frame is reversed on the diagonal line. First
The reliability can be increased as compared with the embodiment. (1) Method of changing the position of the cutout of the original image The cutout direction of the field stop 21 in FIG. 2 is not located in the direction of 45 ° from the horizontal, and preferably in the direction of 22.5 ° from the horizontal (or vertical). In some cases, as shown in FIG. 14, the notch detection is performed by dividing the notch into eight quadrants I to VIII. The notch is detected in the same manner as in the first embodiment. Increases certainty but requires changes to the fundus camera. (2) Method of detecting frame shape of slide mount The lens 204 is made a variable-magnification lens, and by detecting the shape of the film window W opened in the mount (slide frame S), the nipple and macula are substantially horizontal. It can be determined whether or not it is placed in the direction.

As shown in FIG. 15, the imaging range at the time of image capture
An image of the range b including the slide frame S wider than a is taken. Since the position of the slide frame S is roughly determined by the mount holder, the position of the film window W is roughly determined.

Therefore, as shown in FIG. 16, lines a1 and b1 which do not cross the film window W in the long side direction of the film window W, and c and d cross the film window W in the short side direction. It is possible to determine the four line segments.

If a change in the light amount on the line segments a1 and b1 when scanning with the spot illumination light along each of the line segments a1 and b1 is obtained, there is almost no change in the light amount on the line segments a1 and b1.

On the other hand, when transmissive illumination is used to determine a change in the amount of light on the line segments c and d when scanning with the spot illumination light along the line segments c and d, as shown in FIG. There is a great change in light quantity. Further, when the change in the amount of light on the line segments c and d when scanning with the spot illumination light along the line segments c and d is used, epi-illumination (illumination reflected light) is used (the amount of light reflected by the illumination). 17), there is a light amount change as shown in FIG. 17 (b). (Since the transmittance / reflectance of the portion other than the image of the film is several percent or less, it is preferable to use epi-illumination.) Therefore, if such a change in the amount of light is detected, the direction of the slide frame s can be detected. it can. Note that FIG.
Although four line segments are shown in the example, the above two line segments which are orthogonal to each other in principle may be used. The lens 204 can use a zoom lens or a variable power lens. In the case of zooming, it is performed by the central processing unit. The detection of the frame may be performed using another imaging device.

In this embodiment, the line segments a1, b1, c, d
The direction in which the long side direction and the short side direction of the slide frame s are set is detected and determined from the above change in the amount of light, but the present invention is not necessarily limited to this.
For example, a square portion surrounded by the line segments a1, b1, c, and d is scanned by linear illumination light in the direction from the line segment a1 to b1, and is scanned in the direction from the line segment c to d. The direction of the long side and the short side of the slide frame s may be detected and determined based on the change in the light amount.

[0056]

As described above, according to the first aspect of the present invention, there is provided a fundus image processing apparatus for digitizing a fundus photograph by a photographic image reading apparatus, wherein the fundus image is read by the photographic image reading apparatus. With the configuration including the image arrangement discriminating means for discriminating rotation or front / back, it is possible to automatically perform rotation of the image up / down or 90 ° or discrimination of front / back.

According to a second aspect of the present invention, when the orientation of the image determined by the image arrangement determining unit is not the normal direction, a warning unit for warning the fact or a display indicating that the image is not the normal direction is displayed. Since the display is provided, if the orientation of the image determined by the image arrangement determining means is not the correct orientation, for example, if the fundus photograph is rotated upside down or 90 ° or input incorrectly, A warning can be issued to the user by a warning means, or the operator can be notified of this on a display.

Further, the invention according to claim 3 is characterized in that, when reading the fundus photograph with the photographic image reading device, if the fundus photograph is input upside down, rotated by 90 ° or wrongly turned upside down, the photographic image reading device may be used. The configuration has a coordinate conversion means for rotating the read image position data vertically or by 90 ° or converting the coordinates of the front and back to the coordinates of the image direction data in the correct direction. When the input is performed, the image position data read by the photographic image reading device is converted into the regular image position data, and the reliable image reading can be easily performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of an optical system of a fundus camera.

FIG. 2 is an explanatory view showing the field stop of FIG. 1;

FIGS. 3A and 3B are explanatory diagrams showing a fundus image taken by the fundus camera shown in FIG. 1;

FIG. 4 is a histogram of the number of pixels with respect to the light intensity of the fundus image shown in FIGS. 3 (a) and 3 (b).

FIG. 5 shows an example of a block diagram of a filing system according to the present invention.

FIG. 6A is an explanatory diagram showing an example of a fundus image, and FIG.
FIG. 7A is an explanatory diagram illustrating a change in brightness when the fundus image is scanned in FIG.

FIG. 7 is an explanatory diagram for calculating a position of a notch in the fundus image of FIG. 6;

FIG. 8 is an explanatory diagram for determining left and right of a fundus image.

FIG. 9 is an explanatory diagram for determining left and right of a fundus image.

FIG. 10A is an explanatory view showing an example of a photo positioning holder provided on a light box, respectively.
(b) is a side view of FIG. 10 (a).

11A is an explanatory view showing an example of a photo positioning holder provided on a light box, and FIG.
(b) is a side view of FIG. 11 (b).

FIGS. 12A and 12B are explanatory diagrams for discriminating left, right, up, down, front and back of a fundus image read from a photograph or the like;

FIGS. 13A and 13B are explanatory diagrams for discriminating left, right, up, down, front and back of a fundus image read from a photograph or the like.

FIGS. 14A and 14B are explanatory diagrams showing another example of a notch for discrimination such as right, left, up, down, front and back of a fundus image read from a photograph or the like.

FIG. 15 is an explanatory diagram illustrating an example of detecting a slide frame shape of a slide photograph.

FIG. 16 is an explanatory diagram showing an example of detecting a slide frame shape of a slide photograph.

17 (a) and (b) are explanatory diagrams showing a change in the amount of light when scanning the shape of the slide frame in FIG. 16 is detected.

[Explanation of symbols]

B: buzzer (warning means) GK: fundus camera (imaging device) FS: filing device 101 ': cutout image section 206: video camera (photograph image reading device) 207: frame memory 212: central processing unit (discrimination) Means, image arrangement determination means, coordinate conversion means) 214 ··· display

Claims (3)

[Claims] 1. A fundus image processing apparatus for digitizing a fundus photograph by a photographic image reading device, comprising: an image arrangement discriminating means for discriminating whether the fundus photograph read by the photographic image reading device is up, down, rotated by 90 ° or front and back. A fundus image processing apparatus, characterized in that: 2. If the orientation of the image determined by the image arrangement determining unit is not the normal direction, a warning unit for warning the fact or a display for displaying that the direction is not the normal direction are provided. The fundus image processing apparatus according to claim 1, wherein: 3. When reading the fundus photograph with the photographic image reading device, if the fundus photograph is input upside down, rotated 90 °, or turned upside down, the image position data read by the photographic image reading device is 2. The fundus image processing apparatus according to claim 1, further comprising a coordinate conversion unit configured to convert the coordinates of up / down or 90 ° rotation or the front / back coordinates into the coordinates of image position data in a correct direction.