CN108882835B

CN108882835B - Endoscope image signal processing device and method, and storage medium

Info

Publication number: CN108882835B
Application number: CN201780020273.4A
Authority: CN
Inventors: 藏本昌之
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2016-03-30
Filing date: 2017-03-24
Publication date: 2021-01-29
Anticipated expiration: 2037-03-24
Also published as: WO2017170232A1; CN108882835A; JPWO2017170232A1; JP6580778B2

Abstract

The invention provides an endoscope image signal processing device and method and a storage medium capable of maintaining color balance of a normal mucosa in a bright range and a dark range. The RGB gray scale table is set for each brightness or R component size, and the RGB gray scale table for each brightness or R component size is set in such a way that when an RGB signal with an RGB ratio of the 1 st ratio is input to each RGB gray scale table, an output value with the RGB ratio of the 2 nd ratio is output from each RGB gray scale table, and a gray scale processing part (62b) acquires the brightness or R component according to the RGB signal and carries out gray scale processing on the RGB signal acquired by shooting the shooting object by using the RGB gray scale table corresponding to the brightness or the R component size.

Description

Endoscope image signal processing device and method, and storage medium

Technical Field

The present invention relates to an endoscopic image signal processing apparatus and method, and a program for performing gradation processing on RGB signals obtained by imaging an imaging target using an endoscope.

Background

In the medical field, diagnosis using an endoscope system including a light source device, an endoscope, and a processor device is widely performed. In particular, due to the improvement in performance of the color endoscope system, the diagnosis of a disease condition such as a mucous membrane of a digestive organ is performed by observing the color of a captured endoscopic image.

For example, it is known that when the gastric mucosa is infected with helicobacter pylori, which is considered to be the cause of gastric cancer, red inflammatory parts appear in atrophy or spots on the mucosa of the stomach. Therefore, the presence or absence of infection with helicobacter pylori is confirmed by observing the color of the atrophic or inflamed portion using an endoscopic image.

Here, for example, patent document 1 proposes that in an endoscopic image captured by irradiating an imaging target with white light, gradation processing is performed on RGB signals output from an imaging element using an RGB gradation table in order to highlight a blood vessel, a lesion portion, or the like.

Prior art documents

Patent document

Patent document 1: japanese patent No. 5467754

Patent document 2: japanese patent laid-open No. 2000-330037

Patent document 3: japanese patent laid-open publication 2011-10131

Disclosure of Invention

Technical problem to be solved by the invention

However, for example, when an endoscope is inserted into a lumen organ such as a large intestine or a small intestine to photograph a mucous membrane, the illumination light is sufficiently irradiated to the distal end of the endoscope in the range of the proximal side, but the illumination light cannot sufficiently reach the range of the distal side, resulting in a dark image.

When the RGB signals obtained by imaging an imaging object in which such a bright range and a dark range are mixed are subjected to gradation processing using the same gradation table, the degree of emphasis differs between the bright range and the dark range, and the emphasis is too strong or conversely too weak, and there is a problem that an image in which the color balance of the normal mucous membrane differs between the bright range and the dark range is imaged. In the following, a specific example will be described, but here, for convenience of description, a case will be described in which an imaging target is regarded as gray and the ratio of the R signal, the G signal, and the B signal is 1: 1.

For example, when the R component gray scale RC, the G component gray scale G C, and the B component gray scale BC are set as shown in fig. 15, when the input values of the R signal, the G signal, and the B signal are a, the output values based on the gradation processing become R _ out1, G _ out1, and B _ out 1. In contrast, when the input values of the R signal, the G signal, and the B signal are B, the output values based on the gradation processing become R _ out2, G _ out2, and B _ out 2. If the color balance of the output values is to be kept constant under the conditions of the input value a and the input value B, the output values are required to be present on the dotted line shown in fig. 15, but the output values G _ o ut2 and B _ out2 with respect to the input value B become larger than the dotted line, and as a result, an image with a stronger cyan color is obtained as compared with the case where the input value is a. That is, the color balance of RGB differs depending on the luminance of the input value.

In such an image with a color balance lost, for example, there is a possibility that the image diagnosis cannot be accurately performed due to a non-emphasized range with red color or a change in color tone of the normal mucous membrane.

Patent document 2 discloses that the R signal, the G signal, and the B signal are subjected to gamma correction, and the gamma correction curve is changed for a bright image and a dark image.

Patent document 3 discloses that a luminance level is detected from a signal of a dominant color (for example, red) in an image, and a gradation process is performed on an RGB image signal based on the luminance level.

However, the methods described in patent documents 2 and 3 cannot suppress the imbalance of the color balance as described above.

In view of the above-described problems, the present invention provides an endoscopic image signal processing apparatus, method, and program that can maintain the color balance of, for example, a normal mucous membrane in a bright range and a dark range even when an image pickup object in which a bright range and a dark range are mixed is picked up.

Means for solving the technical problem

The 1 st endoscope image signal processing device of the present invention includes: an image signal acquisition unit that acquires an RGB signal obtained by imaging an imaging target using an endoscope; and a gradation processing section for performing gradation processing on the RGB signal using an RGB gradation table in which input values and output values of RGB are associated with each other, the RGB gradation table being set for each of luminance or R component sizes, and the RGB gradation table for each of the luminance or R component sizes being set such that, when an RGB signal having an RGB ratio of 1 st ratio is input to each of the RGB gradation tables, an output value having an RGB ratio of 2 nd ratio is output from each of the RGB gradation tables, and the gradation processing section acquiring the luminance or R component from the RGB signal and performing gradation processing using the RGB gradation table corresponding to the luminance or R component size.

Here, the "luminance" represents the degree of luminance, and is considered to include also the lightness on a so-called color space.

In the endoscope image signal processing apparatus according to the 1 st aspect of the present invention, the gradation processing section may acquire the luminance or the R component for each pixel constituting the RGB signal, and perform the gradation processing for each pixel.

In the endoscope image signal processing apparatus according to the above-described aspect 1 of the present invention, the RGB gradation table may be set to only a part of the brightness or the R component size.

In the endoscope image signal processing apparatus according to the 1 st aspect of the present invention, the gradation processing section may perform the gradation processing by interpolating an RGB gradation table set for each of partial luminance and R component size.

In the 1 st endoscopic image signal processing apparatus according to the present invention, the RGB gradation table for each luminance or R component size can output an output value in which the lightness and saturation change while maintaining the hue when the RGB signal of the 1 st ratio is input.

Further, the 1 st endoscopic image signal processing apparatus according to the present invention includes: the low-frequency image generation processing unit generates a low-frequency image by performing low-frequency image generation processing on the RGB signals, and the gradation processing unit can acquire luminance or an R component from the low-frequency image.

In the 1 st endoscopic image signal processing apparatus according to the present invention, RGB signals obtained by imaging an imaging target irradiated with illumination light including narrow-band light can be used as the RGB signals.

In the 1 st endoscopic image signal processing device according to the present invention, blue narrow-band light or green narrow-band light can be used as the narrow-band light.

In the endoscope image signal processing apparatus according to the above-described aspect 1 of the present invention, RGB signals obtained by imaging a luminal organ as an imaging target can be used as the RGB signals.

In the 1 st endoscopic image signal processing apparatus according to the present invention, the 1 st ratio is preferably an RGB ratio of RGB signals obtained by imaging a normal mucous membrane.

In the endoscope image signal processing apparatus according to the above-described aspect 1 of the present invention, it is preferable that, in each of the RGB gradation tables, a ratio of an R output value to an R input value when an RGB signal obtained by imaging a normal mucous membrane is input is larger than a ratio of an R output value to an R input value when an RGB signal obtained by imaging a normal mucous membrane is input.

In the endoscope image signal processing apparatus according to the above-described aspect 1 of the present invention, it is preferable that, in each of the RGB gradation tables, a ratio of an R output value to an R input value when an RGB signal obtained by imaging a atrophic mucous membrane is input is smaller than a ratio of an R output value to an R input value when an RGB signal obtained by imaging a normal mucous membrane is input.

The 2 nd endoscopic image signal processing apparatus according to the present invention is characterized by comprising: an image signal acquisition unit that acquires an RGB signal obtained by imaging an imaging target using an endoscope; and a gradation processing unit that performs gradation processing on the RGB signal using an RGB gradation table in which input values and output values of RGB are associated with each other, wherein the RGB gradation table is set for each luminance or R component size, and the RGB gradation table for each luminance or R component size is set such that, when an RGB signal obtained by imaging a normal mucosa having an RGB ratio of 1 st is input to each RGB gradation table, an output value having an RGB ratio of 2 nd is output from each RGB gradation table, and the gradation processing unit obtains luminance or R component for each pixel constituting the RGB signal, and performs gradation processing on each pixel using the RGB gradation table corresponding to the luminance or R component size.

An endoscopic image signal processing method for acquiring RGB signals acquired by imaging an imaging object using an endoscope and performing gradation processing on the RGB signals using an RGB gradation table in which input values and output values of RGB are associated with each other, wherein the RGB gradation table is set for each luminance or R component size, and the RGB gradation table for each luminance or R component size is set such that, when an RGB signal having an RGB ratio of the 1 st ratio is input to each RGB gradation table, an output value having an RGB ratio of the 2 nd ratio is output from each RGB gradation table, luminance or R component is acquired from the RGB signals, and gradation processing is performed using the RGB gradation table corresponding to the luminance or R component size.

An endoscope image signal processing program according to the present invention causes a computer to function as: an image signal acquisition unit that acquires an RGB signal obtained by imaging an imaging target using an endoscope; and a gradation processing section for performing gradation processing on the RGB signal using an RGB gradation table in which input values and output values of RGB are associated with each other, wherein the RGB gradation table is set for each of the luminance or R component sizes, and the RGB gradation table for each of the luminance or R component sizes is set such that, when an RGB signal having an RGB ratio of the 1 st ratio is input to each of the RGB gradation tables, an output value having an RGB ratio of the 2 nd ratio is output from each of the RGB gradation tables, and the gradation processing section acquires the luminance or R component from the RGB signal and performs gradation processing using the RGB gradation table corresponding to the luminance or R component size.

Effects of the invention

According to the endoscope image signal processing apparatus and method and the program of the present invention, the RGB gradation table is set for each brightness or R component size. Then, the RG B gradation table for each luminance or R component size is set such that, when an RGB signal having an RGB ratio of the 1 st ratio is input to each of the RGB gradation tables, an output value having an RGB ratio of the 2 nd ratio is output from each of the RGB gradation tables. Since the setting is performed based on such RGB gradation tables, the luminance or R component is acquired from the RGB signal obtained by imaging the imaging target using the endoscope, and the gradation processing is performed on the RGB signal using the RGB gradation tables according to the magnitude of the luminance or R component, even when imaging targets in which a bright range and a dark range are mixed, the color balance of, for example, a normal mucous membrane can be maintained in the bright range and the dark range.

Drawings

FIG. 1 is a view showing a schematic configuration of an endoscope system using an embodiment of an endoscopic image signal processing device according to the present invention

FIG. 2 is a block diagram showing the internal configuration of the endoscope system according to embodiment 1

FIG. 3 is a graph showing the spectral spectrum of white light

FIG. 4 is a diagram showing a spectral spectrum of narrow-band light

FIG. 5 is a block diagram showing a specific configuration of a gradation processing section of the normal light image generating section

FIG. 6 is a diagram showing an example of an RGB gray scale table for each luminance

FIG. 7 is a block diagram showing a specific configuration of a gradation processing section of a narrow-band light image generating section

FIG. 8 is a diagram showing an example of RGB gray scale table for each luminance used in the special light observation mode

FIG. 9 is a diagram showing another example of the RGB gray scale table for each luminance used in the special light observation mode

FIG. 10 is a flowchart for explaining the operation of the endoscope system according to embodiment 1

FIG. 11 is a block diagram showing the internal configuration of a gradation processing section of the endoscope system according to embodiment 2

FIG. 12 is a view showing an example of a C-gray scale, an H-gray scale, and an L-gray scale

Fig. 13 is a block diagram showing a modification of the endoscope system according to embodiment 1

FIG. 14 is a graph showing emission spectra of violet light V, blue light B, green light G, and red light R

FIG. 15 is a diagram for explaining gradation processing using a conventional RGB gradation table

Detailed Description

An endoscope system according to embodiment 1 using an endoscopic image signal processing apparatus and method and a program according to the present invention will be described in detail below with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of an endoscope system 10 according to the present embodiment.

The endoscope system 10 of the present embodiment includes an endoscope 12, a light source device 14, a processor device 16, a display 18, and an input device 20. Endoscope 12 is optically connected to light source device 14 and electrically connected to processor device 16.

The endoscope 12 includes an insertion portion 21 inserted into the subject, an operation portion 22 provided at a proximal end portion of the insertion portion, a bending portion 23 provided at a distal end side of the insertion portion 21, and a distal end portion 24. The operation portion 22 is provided with an angle knob 22a, and the bending portion 23 performs a bending operation by rotating the angle knob 22 a. With this bending action, the distal end portion 24 is oriented in a desired direction.

The operation unit 22 is provided with a mode selector switch 22b and a zoom operation unit 22 c. The mode changeover switch 22b is used for a changeover operation between 2 modes of the normal light observation mode and the narrow band light observation mode. The normal light observation mode is a mode in which white light is used for illumination of an imaging target in a subject. The narrow-band light observation mode is a mode in which blue-colored narrow-band light is used for illumination of an imaging target in a subject, and is a mode in which a change in mucosal color due to atrophic gastritis or a vascular fluoroscopic image is emphasized. The zoom operation unit 22c is used for zooming operation for driving a zoom lens 47 (see fig. 2) in the endoscope 12 to enlarge an imaging target.

The display 18 and the input device 20 are electrically connected to the processor device 16. The display 18 displays an endoscopic image captured by the endoscope 12 and color numerical value information described later. The input device 20 receives input operations such as function setting, and includes a keyboard, a mouse, and the like. In addition, the display 18 and the input device 20 may be used in combination by using a touch panel.

Fig. 2 is a block diagram showing an internal configuration of the endoscope system 10 according to the present embodiment.

The light source device 14 includes a blue laser source 34 that emits a blue laser beam having a center wavelength of 445nm and a blue-violet laser source 36 that emits a blue-violet laser beam having a center wavelength of 405 nm. The

light sources

34 and 36 are independently controlled by the light source control unit 40, and the ratio of the amount of light emitted from the blue laser light source 34 to the amount of light emitted from the blue-violet laser light source 36 can be changed.

When the normal light observation mode is selected, the light source control section 40 mainly drives the blue laser light source 34. In addition, the blue-violet laser light source 36 may be controlled so as to emit the blue-violet laser light weakly.

In contrast, in the narrow-band light observation mode, the light source control unit 40 drives both the blue laser light source 34 and the blue-violet laser light source 36, and controls the light intensity of the blue laser light to be larger than the light intensity of the blue-violet laser light. Further, it is preferable that the half width of the blue laser beam or the blue-violet laser beam is about ± 2nm and blue narrow-band light is used. As the blue laser source 34 and the blue-violet laser source 36, a large-area InGaN laser diode, an InGaAsN laser diode, a GaAsN laser diode, or the like can be used. The light source may be configured to use a light emitting body such as a light emitting diode.

The laser beams emitted from the

light sources

34 and 36 enter the Light Guide (LG)41 through an optical component (not shown) such as a condenser lens. The light pipe 41 is housed within the universal cord 13 and is optically connected to the endoscope 12.

The blue laser light or the blue-violet laser light propagates to the distal end portion 24 of the endoscope 12 via the light guide 41. Further, as the light guide 41, a multimode fiber can be used.

The distal end portion 24 of the endoscope 12 includes an illumination optical system 24a and an imaging optical system 24 b. The illumination optical system 24a is provided with a fluorescent material 44 and an illumination lens 45, on which the blue laser light or the blue-violet laser light emitted from the light guide 41 enters. The fluorescent material 44 is excited by irradiation with blue laser light, and fluorescence is emitted from the fluorescent material 44. Also, a part of the blue laser light directly transmits the fluorescent material 44. The blue-violet laser light does not excite the phosphor 44 and transmits. The light transmitted through the fluorescent body 44 is irradiated to the imaging object via the illumination lens 45.

Here, in the normal light observation mode, the blue laser light is mainly incident on the fluorescent material 44. Therefore, as shown in fig. 3, white light WL obtained by combining blue laser light BL and fluorescent light FL emitted from the fluorescent material 44 is irradiated to the imaging target. On the other hand, in the narrow-band observation mode, both the blue-violet laser light and the blue laser light enter the fluorescent material 44. Therefore, as shown in fig. 4, the light SL combined with the blue-violet laser light VL, the blue laser light BL, and the fluorescent light FL is irradiated to the imaging target. In this narrow-band observation mode, since the blue-violet laser light, which is narrow-band light, is included in addition to the blue laser light, a wide-band light containing a large amount of blue components and having a wavelength range substantially over the entire visible light is irradiated to the imaging target. In the present specification, light irradiated to an imaging target in the narrow-band light observation mode is simply referred to as narrow-band light. That is, the light SL shown in fig. 4 is simply referred to as narrow-band light SL.

The blue narrow-band light such as the blue laser light and the blue-violet laser light according to the present embodiment is absorbed more greatly by a light-absorbing substance in the mucosa, specifically, blood (particularly hemoglobin) contained in a large amount in the digestive organ. Therefore, when imaging is performed in the narrow band observation mode, the difference between the normal mucous membrane region and the atrophic mucous membrane region can be increased.

The phosphor 44 preferably includes a plurality of phosphors (e.g., YAG (Yttrium Aluminum Garnet)) that absorb part of the blue laser beam and emit light by green to yellow excitation, or BAM (BaMgAl)₁₀O₁₇) Etc. phosphors). As in the present embodiment, when a semiconductor light emitting element is used as an excitation light source for the phosphor 44, it is possible to obtain high-intensity white light with high luminous efficiency, to easily adjust the intensity of the white light, and to suppress variations in the color temperature and chromaticity of the white light to a small level.

In the present embodiment, the fluorescent material 44 is provided at the distal end portion 24 of the endoscope 12, but the fluorescent material 44 may be provided in the light source device H instead. In this case, it is preferable to dispose the phosphor 44 between the light guide 41 and the blue laser light source 34.

The imaging optical system 24b of the endoscope 12 includes an imaging lens 46, a zoom lens 47, and an imaging element 48. The reflected light from the imaging object enters the imaging element 48 through the imaging lens 46 and the zoom lens 47. Thereby, the reflected image of the imaging target is formed on the imaging element 48. The zoom lens 47 is moved by operating the zoom operation unit 22 c.

The imaging element 48 is a color image sensor, and captures a reflected image of an imaging target and outputs a RAW signal. The imaging element 48 is preferably a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, or the like.

The imaging element 48 of the present embodiment is a synchronous imaging element in which RGB color filters are provided on an imaging surface. An R signal of an R component is output from an element provided with an R (red) color filter, a G signal of a G component is output from an element provided with a G (green) color filter, and a B signal of a B component is output from an element provided with a B (blue) color filter. Hereinafter, the R signal, the G signal, and the B signal may be collectively referred to as an RGB signal. The filter array may be a bayer array or a honeycomb array.

The image forming element 48 may be an image sensor including CMYG filters of C (cyan), M (magenta), Y (yellow), and G (green) on an image forming surface. In the case of an image sensor having CMYG filters, a C signal of a C component is output from an element provided with a C (cyan) color filter, an M signal of an M component is output from an element provided with an M (magenta) color filter, a Y signal of a Y component is output from an element provided with a Y (yellow) color filter, and a G signal of a G component is output from an element provided with a G (green) color filter.

The RGB signals output from the imaging element 48 are output to a CDS/AGC circuit 50. The CDS/AGC circuit 50 performs correlated double sampling (CDS (correlated double sampling)) or automatic gain control (AGC (auto gain control)) on an analog signal, that is, an RGB signal. The RGB signals passing through the CDS/AGC circuit 50 are subjected to gamma conversion in a gamma conversion section 51, and then converted into digital signals by an a/D conversion section 52. The a/D converted RGB signals are input to the processor means 16.

The processor device 16 includes an image signal acquisition unit 60, an interference removal unit 61, a normal light image generation unit 62, a narrow-band light image generation unit 63, and a display control unit 65. The processor device 16 is a computer including a CPU (Central Processing Unit), a semiconductor memory, a hard disk, and the like, and is equipped with an embodiment of the endoscopic image signal Processing program according to the present invention. The CP U executes the endoscopic image signal processing program, whereby the above-described units function.

The image signal acquisition unit 60 acquires RGB signals output from the endoscope 12. The RGB signals acquired by the image signal acquiring unit 60 are temporarily stored in a memory or the like. The RGB signals acquired by the image signal acquisition unit 60 are subjected to demosaicing processing by a demosaicing processing unit, not shown, to generate R, G, and B signals for each pixel.

The interference removing unit 61 performs interference removing processing on the RGB signals subjected to the demosaicing processing. In particular a moving average filtering or median filtering process.

The normal light image generating unit 62 includes a matrix processing unit 62a, a gradation processing unit 62b, a three-dimensional LUT processing unit 62c, a color enhancing unit 62d, and a structure enhancing unit 62 e. The matrix processing unit 62a, the gradation processing unit 62b, and the three-dimensional LUT processing unit 62c perform color conversion processing on the RGB signals. Specifically, the matrix processing unit 62a performs 3 × 3 matrix processing on the RGB signals, the gradation processing unit 62b performs gradation processing, and the three-dimensional LUT processing unit 62c performs three-dimensional LUT processing.

The gradation processing unit 62b stores in advance an RGB gradation table in which input values and output values of RGB signals are associated with each other, and the gradation processing unit 62b performs gradation processing on the input RGB signals using the RGB gradation table.

Fig. 5 is a block diagram showing a specific configuration of the gradation processing section 62 b. As shown in fig. 5, the gradation processing section 62b includes a 1 st LUT processing section 70, a 2 nd LUT processing section 71, and a luminance calculating section 72.

The 1 st LUT processing part 70 is preset with RGB gradation tables for normal image used when generating a normal image in the normal light observation mode.

The 2 nd LUT processing part 71 is preset with RGB gradation tables for the special image used when the special image is generated in the normal light observation mode.

The 1 st LUT processing part 70 and the 2 nd LUT processing part 71 are switched between the case of receiving the command input for the normal image generation and the case of receiving the command input for the special image generation.

The 2 nd LUT processing part 71 is set with RGB gradation tables for each luminance calculated from the RGB signals. The luminance calculating section 72 calculates the luminance of the RGB signal input to the gradation processing section 62 b. The luminance calculated by the luminance calculating section 72 is input to the 2 nd LUT processing section 71, and the 2 nd LUT processing section 71 performs gradation processing on the RGB signal using the RGB gradation table corresponding to the input luminance.

Fig. 6I and 6II are diagrams showing an example of the RGB gradation table set for each luminance. Hereinafter, the RGB gray scale tables shown in fig. 6I and 6II will be described, but here, for convenience of description, a case will be described in which an image pickup object is gray, and the ratio of the R signal, the G signal, and the B signal output from the endoscope 12 is 1: 1.

Fig. 6I shows an example of RGB gray scales used when the input values, i.e., the R signal, the G signal, and the B signal, are R _ in1, G _ in1, and B _ in1, respectively, and fig. 6II shows an example of RGB gray scales used when the input values, i.e., the R signal, the G signal, and the B signal, are R _ in2, G _ in2, and B _ in2, respectively. That is, fig. 6I is an RGB gray scale table corresponding to the luminances calculated by R _ in1, G _ in1, and B _ in1, and fig. 6II is an RGB gray scale table corresponding to the luminances calculated by R _ in2, G _ in2, and B _ in 2. In fig. 6I and 6II, R _ in1, G _ in1, and B _ in1 are denoted by "a" and R _ in2, G _ in2, and B _ in2 are denoted by "B".

As shown in fig. 6I and 6II, the RGB gradation tables include R gradation tables RC1 and RC2 that associate input values and output values of R signals with each other; g-gray scales GC1, GC2 which associate input values of G signals with output values, and B-gray scales BC1, BC2 which associate input values of B signals with output values.

R grey tables RC1, RC 2; the G and B gray scales GC1 and GC2 and BC1 and BC2 are preferably gray scales in which the hue and chroma of a specific imaging target such as a normal mucous membrane are set at predetermined positions and the color of another imaging target such as red is emphasized. That is, it is preferable to set the RGB ratio to a predetermined ratio after the gradation processing with respect to the RGB signals indicating the normal mucous membrane, and to set the ratio of the R component to be larger than the predetermined ratio after the gradation processing with respect to the RGB signals indicating the redness. Such a gradation table can be set by acquiring in advance the distribution of RGB signals representing normal mucosa and the distribution of RGB signals representing redness, and analyzing the relationship between these distributions and output values.

As described above, the RGB gradation table shown in fig. 6I and the RGB gradation table shown in fig. 6II are RGB gradation tables set for each luminance, but these RGB gradation tables are set so that the RGB ratio becomes a predetermined ratio with respect to the input of the RGB signal of the predetermined ratio even when the luminance calculated from the RGB signal of the input value changes. That is, when RGB signals having an RGB ratio of the 1 st ratio (for example, RGB signals obtained by imaging a normal mucous membrane) are input to the respective RGB gradation tables shown in fig. 6I and 6II, an output value having an RGB ratio of the 2 nd ratio is set to be output from the respective RGB gradation tables.

Specifically, the RGB gradation table shown in fig. 6I is an RGB gradation table used when the input value is a, the output value of the R signal becomes R _ out1, the output value of the G signal becomes G _ out1, and the output value of the B signal becomes B _ out 1. On the other hand, the RGB gradation table shown in fig. 6II is an RGB gradation table used when the input value is B, the output value of the R signal becomes R _ out2, the output value of the G signal becomes G _ out2, and the output value of the B signal becomes B _ out 2. The RGB gradation tables shown in fig. 6I and 6II are set so that the ratio of R _ out1 to G _ out1 to B _ out1 is the same as the ratio of R _ out2 to G _ out2 to B _ out 2. In addition, it can be seen that the straight lines RL, BL, and GL shown in fig. 6I and the straight lines R L, BL, and GL shown in fig. 6II are the same straight lines, and the ratio of R _ out1 to G _ out1 to B _ out1 and the ratio of R _ out2 to G _ out2 to B _ out2 are not changed.

In this way, even when the RGB gradation table is set for each luminance and the luminance of a predetermined input value changes, the ratio of the R signal, the G signal, and the B signal set as the output values does not change, and thus, for example, when a luminal organ such as a large intestine or a small intestine is imaged by the endoscope 12, the color balance of, for example, a normal mucous membrane can be maintained in the imaging range before and behind the luminance difference, and an image representing a more accurate color can be generated. This enables more accurate image diagnosis.

Specifically, the 2 nd LUT processing part 71 calculates the luminance Y for each pixel in accordance with the following equation, and calculates the output values R _ out, G _ out, and B _ out for each pixel using the RGB gray scale corresponding to the luminance. In the following formula, LUT _ R [ R ] [ Y ] is an R gray scale table corresponding to luminance, LUT _ G [ G ] [ Y ] is a G gray scale table corresponding to luminance, and LUT _ B [ B ] [ Y ] is a B gray scale table corresponding to luminance.

Y＝0.3×R_in+0.6×G_in+0.1×B_in

R_out＝LUT_R[R_in][Y]

G_out＝LUT_G[G_in][Y]

B_out＝LUT_B[B_in][Y]

The luminance Y is 0 to 255, but the RGB gradation table does not need to be set for all the values 0 to 255, and only a part of the luminance values of 0 to 255 may be set.

For example, when RGB gradation tables corresponding to the luminance Y calculated from the input values R _ in, G _ in, and B _ in are set in advance, the output values R _ out, G _ out, and B _ out may be calculated using the RGB gradation tables set for the luminance values before and after the luminance Y. Specifically, the RGB gradation tables set for the front and rear luminances may be interpolated and used.

When the imaging device 48 includes a color filter of a complementary color system of CMYG, the CMYG signals may be converted into RGB signals, and then subjected to gradation processing using the RGB gradation table.

Returning to fig. 2, the color enhancer 62d receives a setting input from the user and performs various color enhancement processes on the color-converted RGB signal. The structure enhancing unit 62e performs structure enhancing processing such as spatial frequency enhancement on the RGB signal having been subjected to the color enhancing processing.

The matrix processing unit 62a, the color enhancement unit 62d, and the structure enhancement unit 62e are preset with a parameter for generating a normal image and a parameter for generating a special image, respectively.

The normal image generation and the special image generation are switched by a user inputting a command from the input device 20. The operation unit 22 may be provided with a switch for switching between normal image generation and special image generation, without being limited to command input from the input device 20.

When a command for normal image generation is input by the user, the RGB signals input to the normal light image generator 62 are subjected to normal image processing in each unit, and are output as normal image signals from the normal light image generator 62 to the display controller 65. When a command for generating a special image is input by the user, the RGB signals input to the normal light image generating unit 62 are subjected to special image processing in each unit, and are output as special image signals from the normal light image generating unit 62 to the display control unit 65.

The narrow-band light image generating section 64 includes a matrix processing section 64a, a gradation processing section 64b, a three-dimensional LUT processing section 64c, a color enhancing section 64d, and a structure enhancing section 64 e. The matrix processing unit 64a, the gradation processing unit 64b, and the three-dimensional LUT processing unit 62c perform color conversion processing for narrow-band images on the RGB signals. Specifically, the matrix processing unit 64a performs 3 × 3 matrix processing on the RGB signals, the gradation processing unit 64b performs gradation processing, and the three-dimensional LUT processing unit 64c performs three-dimensional LUT processing.

Similarly to the gradation processing section 62b, an RGB gradation table associating input values and output values of RGB signals is set in advance in the gradation processing section 64b, and the gradation processing section 64b performs gradation processing on the input RGB signals using the RGB gradation table.

As shown in fig. 7, the gradation processing section 64b has the same basic configuration as the gradation processing section 62b, and includes a 1 st LUT processing section 73, a 2 nd LUT processing section 74, and a luminance calculating section 75.

The 1 st LUT processing part 73 has previously set RGB gradation tables for narrow band images used when generating narrow band images in the narrow band light observation mode.

The 2 nd LUT processing part 74 is preset with RGB gradation tables for the special narrow-band image used when the special narrow-band image is generated in the narrow-band light observation mode.

The 1 st LUT processing part 73 and the 2 nd LUT processing part 74 are switched between the case of receiving the command input for the narrow band image generation and the case of receiving the command input for the special narrow band image generation.

Further, the 2 nd LUT processing part 74 has an RGB gradation table set for each luminance, as in the 2 nd LUT processing part 71 of the normal light image generating part 62. The RGB gradation table for each luminance is also set such that, when an RG B signal having an RGB ratio of the 1 st ratio is input to each RGB gradation table for each luminance, an output value having an RGB ratio of the 2 nd ratio is output from each RGB gradation table. Fig. 8 and 9 are diagrams showing a specific example of the RBG gradation table set in the gradation processing section 64 b.

The RGB gradation tables shown in fig. 8I and 8II are set so that the RGB ratio (1 st ratio) of the input RGB signal and the RGB ratio (2 nd ratio) of the RGB signal after the gradation processing become the same. The RGB gradation table shown in fig. 8I is an RGB gradation table used when the luminance is Y82, and the RGB gradation table shown in fig. 8II is an RGB gradation table used when the luminance is Y143.

The RGB gray scale table (RC1, GC1, BC1) shown in fig. 8I outputs R _ out 128, G _ out 67, B _ in 34 RGB signal outputs R _ out 128, G _ out 67, B _ out 34. At this time, the RGB ratio of the input RGB signals is 1: 0.53: 0.27, and the RGB ratio of the output values is 1: 0.53: 0.27.

On the other hand, the RGB signals of the RGB gray scale table (RC2, GC2, BC2) shown in fig. 8II, R _ in-224, G _ i n-118, B _ in-59, output values of R _ out-224, G _ out-118, B _ out-59. At this time, the RGB ratio of the input RGB signals is 1: 0.53: 0.27, and the RGB ratio of the output values is 1: 0.53: 0.27.

That is, the RGB gradation table shown in fig. 8I and the RGB gradation table shown in fig. 8II are set such that, when an RGB signal having an RGB ratio of R: G: B of 1: 0.53: 0.27 (1 st ratio) is input, an output value having an RGB ratio of R: G: B of 1: 0.53: 0.27 (2 nd ratio) is output from each of the RGB gradation tables.

Next, the RGB gradation tables shown in fig. 9I and 9II are set such that when the RGB ratio (1 st ratio) of the input RGB signals is R: G: B of 1: 0.53: 0.27, the RGB ratio (2 nd ratio) of the RGB signals after the gradation processing is R: G: B of 1: 0.5: 0.3.

The RGB gradation table (RC1, GC1, BC1) shown in fig. 9I is an RGB gradation table used when the luminance is Y82, and the RGB gradation table shown in fig. 9II is an RGB gradation table used when the luminance is Y143.

The RGB grayscale table shown in fig. 9I outputs RGB signals R _ out 128, G _ out 63, and B _ out 38 of R _ in 34, G _ in 67, and B _ in 128. At this time, as described above, the RGB ratio of the input RGB signals is 1: G: B to 1: 0.53: 0.27, and the RGB ratio of the output values is 1: G: B to 0.5: 0.3.

On the other hand, the RGB signals of the RGB gray scale table (RC2, GC2, BC2) shown in fig. 9II, R _ in-224, G _ i n-118, B _ in-59, output values of R _ out-224, G _ out-111, and B _ out-66. At this time, as described above, the RGB ratio of the input RGB signals is 1: G: B to 1: 0.53: 0.27, and the RGB ratio of the output values is 1: G: B to 0.5: 0.3.

That is, the RGB gradation table shown in fig. 9T and the RGB gradation table shown in fig. 9II are set such that, when an RGB signal having an RGB ratio of R: G: B of 1: 0.53: 0.27 (1 st ratio) is input, an output value having an RGB ratio of R: G: B of 1: 0.5: 0.3 (2 nd ratio) is output from each of the RGB gradation tables.

In the atrophic mucosa to be highlighted in the narrow-band observation mode, when the atrophic mucosa and the normal mucosa have the same brightness, the G signal and the B signal are greater than those of the normal mucosa, and the R signal is less than that of the normal mucosa. Also, regarding redness, when redness is the same brightness as the normal mucosa, the R signal is greater than that of the normal mucosa, and the G signal and B signal are less than those of the normal mucosa. As shown in the RGB gradation tables of fig. 8 and 9, the ratio of the output value to the input value is higher than the reference point for input values higher than the reference point, and the ratio of the output value to the input value is lower than the reference point for input values lower than the reference point, whereby color enhancement can be performed. That is, each RGB gradation table is preferably set such that the larger the input value is, the larger the ratio of the output value to the input value is.

More specifically, in each of the RGB gradation tables, it is preferable that the ratio of the R output value to the R input value when the RGB signals obtained by imaging the normal mucous membrane are input is larger than the ratio of the R output value to the R input value when the RGB signals obtained by imaging the red mucous membrane are input.

In each of the RGB gradation tables, it is preferable that the ratio of the R output value to the R input value when the RGB signals obtained by imaging the atrophic mucosa are input is smaller than the ratio of the R output value to the R input value when the RGB signals obtained by imaging the normal mucosa are input.

Returning to fig. 2, the color enhancement section 64d receives a setting input by the user and further performs various color enhancement processes on the RGB signal whose color conversion has been completed. The structure enhancing unit 64e performs structure enhancing processing such as spatial frequency enhancement on the RGB signal having been subjected to the color enhancing processing.

The matrix processing unit 64a, the color enhancing unit 64d, and the structure enhancing unit 64e are preset with parameters for generating a narrow-band image and parameters for generating a special narrow-band image, respectively.

The narrow-band image generation and the special narrow-band image generation are switched by a user inputting a command from the input device 20. The operation unit 22 may be provided with a switch for switching between narrow-band image generation and special narrow-band image generation, not limited to command input from the input device 20.

When a user inputs a command for narrow-band image generation, the RGB signals input to the narrow-band light image generation unit 64 are subjected to narrow-band image processing in each unit, and are output as a narrow-band image signal from the narrow-band light image generation unit 64 to the display control unit 65. When a command for generating a special narrow-band image is input by the user, the RGB signals input to the narrow-band light image generating unit 64 are subjected to special narrow-band image processing in each unit, and are output as a special narrow-band image signal from the narrow-band light image generating unit 64 to the display control unit 65.

The display control unit 65 converts the normal image signal, the special image signal, the narrow-band image signal, or the special narrow-band image signal output from the normal light image generating unit 62 or the narrow-band light image generating unit 64 into a display image signal that can be displayed on the display 18. The display 18 displays a normal image, a special image, a narrow band image, or a special narrow band image based on the display image signal.

Next, the operation of the endoscope system according to the present embodiment will be described with reference to a flowchart shown in fig. 10.

First, the user operates the mode changeover switch 22b to selectively set the normal light observation mode or the narrow band light observation mode (S10). When the normal light observation mode is set, the endoscope 12 irradiates the imaging target with the white light WL, and the RGB signals output from the imaging element 48 by imaging the imaging target are acquired by the image signal acquisition unit 60 of the processor device 16 and subjected to the demosaicing process (S12).

The RGB signals subjected to the demosaicing process are input to the interference removing unit 61, subjected to the interference removing process by the interference removing unit 61, and then input to the normal light image generating unit 62. The RGB signals input to the normal light image generating unit 62 are subjected to matrix processing in a matrix processing unit 62 a.

When a command for generating a normal image is input by the user (S14, normal image), the RGB signal is input to the 1 st LUT processing part 70 of the gradation processing part 62b, and gradation processing using the RGB gradation table for the normal image is performed on the RGB signal (S24).

The RGB signals subjected to the gradation processing are input to the three-dimensional LUT processing unit 62c, subjected to the three-dimensional LU T processing, and then input to the color enhancement unit 62d to be subjected to the color enhancement processing. Next, the structure enhancement section 62e performs the structure enhancement process on the RGB signal having finished the color enhancement process to generate a normal image signal (S26), and outputs the normal image signal to the display control section 65. The display control section 65 displays a normal image on the display 18 based on the input normal image signal (S28).

When the user intends to end the processing, a processing end command is input to end the processing (S48, yes). Alternatively, when the processing is not ended (S48, "no"), the process returns to S10, and then the normal light observation mode is continued, or the narrow-band light observation mode is switched.

On the other hand, when a command for generating a special image is input by the user (S14, special image), the RGB signals are input to the 2 nd LUT processing part 71 and the luminance calculating part 72. The luminance calculating section 72 calculates the luminance for each pixel from the input RGB signal for each pixel (S16). The luminance calculated by the luminance calculating section 72 is output to the 2 nd LUT processing section 71, and the 2 nd LUT processing section 71 performs gradation processing on the RG B signal for each pixel based on the input luminance using the RGB gradation table for the special image set for each luminance (S18).

The RGB signals subjected to the gradation processing are input to the three-dimensional LUT processing unit 62c, subjected to the three-dimensional LU T processing, and then input to the color enhancement unit 62d to be subjected to the color enhancement processing. Next, the structure enhancement section 62e performs the structure enhancement process on the RGB signal having been subjected to the color enhancement process to generate a special image signal (S20), and outputs the special image signal to the display control section 65. The display control unit 65 displays a special image on the display 18 based on the input special image signal (S22).

When the narrow-band light observation mode is set by the user operating the mode changeover switch 22b, the endoscope 12 irradiates the image pickup object with the narrow-band light SL, and the RGB signals output from the imaging element 48 by picking up the image of the image pickup object are acquired by the image signal acquisition section 60 of the processor device 16 and subjected to the demosaicing process (S30).

The RGB signals subjected to the demosaicing process are input to the interference removing unit 61, subjected to the interference removing process by the interference removing unit 61, and then input to the narrow-band light image generating unit 64. The RGB signals input to the narrow-band light image generating unit 64 are subjected to matrix processing in the matrix processing unit 64a, and then input to the gradation processing unit 64 b.

When a command for generating a narrow band image is input by the user (S32, narrow band image), the RGB signals are input to the 1 st LUT processing part 73 of the tone processing part 64b, and tone processing using the RGB tone table for the narrow band image is performed on the RGB signals (S42).

The RGB signals subjected to the gradation processing are input to the three-dimensional LUT processing unit 64c, subjected to the three-dimensional LU T processing, and then input to the color enhancement unit 64d to be subjected to the color enhancement processing. Next, the structure enhancement section 64e performs the structure enhancement process on the RGB signal having finished the color enhancement process to generate a narrow-band image signal (S44), and outputs the narrow-band image signal to the display control section 65. The display control unit 65 displays the narrow-band image on the display 18 based on the input narrow-band image signal (S46).

On the other hand, when a command for generating a special narrow-band image is input by the user (S32, special image), the RGB signals are input to the 2 nd LUT processing part 74 and the luminance calculating part 75. The luminance calculating section 75 calculates the luminance for each pixel from the input RGB signal for each pixel (S34). The luminance calculated by the luminance calculating unit 75 is output to the 2 nd LUT processing unit 74, and the 2 nd LUT processing unit 74 performs gradation processing on the RGB signal for each pixel based on the input luminance using the RGB gradation table for the special narrow band image set for each luminance (S36).

The RGB signals subjected to the gradation processing are input to the three-dimensional LUT processing unit 64c, subjected to the three-dimensional LU T processing, and then input to the color enhancement unit 64d to be subjected to the color enhancement processing. Next, the structure enhancement section 64e performs the structure enhancement process on the RGB signal having finished the color enhancement process to generate a special narrow-band image signal (S38), and outputs the special narrow-band image signal to the display control section 65. The display control unit 65 displays the special narrow-band image on the display 18 based on the input special narrow-band image signal (S40).

When the user intends to end the processing, a processing end command is input to end the processing (S48, yes). Alternatively, when the processing is not ended (S48, "no"), the process returns to S10, and then the narrow-band light observation mode is continued or the normal light observation mode is switched.

Next, an endoscope system according to embodiment 2 using the endoscope image signal processing device and method and the program of the present invention will be described. Fig. 11 is a diagram showing a schematic configuration of a gradation processing section of the endoscope system according to the present embodiment. Fig. 11 is a diagram collectively showing the gradation processing unit 62b of the normal light image generation unit 62 and the gradation processing unit 64b of the special light image generation unit 64 shown in fig. 2. The

gradation processing sections

62b and 64b of the endoscope system according to embodiment 2 are further provided with low-frequency image

generation processing sections

66 and 67 for the

gradation processing sections

62b and 64b of the endoscope system according to embodiment 1, respectively.

The low-frequency image

generation processing units

66 and 67 perform low-frequency image generation processing on the RGB signals subjected to the demosaicing processing by the image signal acquisition unit 60. The

luminance calculating sections

72 and 75 of the

gradation processing sections

62b and 64b calculate the luminance using the RGB signals subjected to the low-frequency image generation processing in the low-frequency image

generation processing sections

66 and 67. The low-frequency image generation processing is so-called blurring processing, and known filtering processing or the like can be used.

In this way, by using the RGB signals subjected to the low-frequency image generation processing when calculating the luminance, it is possible to remove the interference signals and the like having extremely high luminance, and it becomes easy to grasp the configuration, so it is possible to use a more appropriate RGB gray scale table. The gradation processing unit 62b uses RGB signals that have not been subjected to the low-frequency image generation processing as input values for the gradation processing.

The other configurations are the same as those of the endoscope system 10 according to embodiment 1.

In the endoscope systems 10 and 11 according to embodiments 1 and 2, the R-gray scales RC1 and RC2 are used as RGB gray scales; b gray tables BC1, BC2, and G gray tables GC1 and GC2, and gray tables for directly outputting R _ out, G _ out, and B _ out to R _ in, G _ in, and B _ in of input values are used, but the structure of the RGB gray tables is not limited thereto.

For example, the RGB gradation table may be configured by a color space conversion table for converting an RGB signal into a color space other than RGB, a color space gradation table for performing the conversion, and an RG B conversion table for converting the output value of the gradation table into an RGB signal again. That is, the RGB gradation table of the present invention is considered to include the RGB gradation table in which gradation processing is performed using the gradation table of the color space other than RGB.

Specifically, for example, an RGB signal is converted into a signal of an HCL color space. Then, a C gray scale table In which the luminance In _ L of the input value obtained by the conversion is associated with the output value Out _ C of C (chroma), an H gray scale table In which the luminance In _ L of the input value is associated with the output value Out _ H of H (hue), and an L gray scale table In which the luminance In _ L of the input value is associated with the output value Out _ L of L (lightness) are stored In advance, and the output value Out _ C, Out _ H, Out _ L corresponding to the luminance In _ L is calculated using these gray scale tables.

As shown in fig. 12, the C-gradation table, the H-gradation table, and the L-gradation table are preferably set so that the lightness and the chroma change according to the luminance while maintaining a predetermined hue even if the luminance changes. In this way, since the hue does not change even if the luminance changes, the effect of maintaining the color balance with respect to the change in luminance can be obtained as in the above-described embodiments 1 and 2.

Also, the output value Out _ C, Out _ H, Out _ L is converted again into an RGB signal using an RGB conversion table. The processing after the conversion into RGB signals is the same as in the above-described embodiments 1 and 2.

Further, although the endoscope systems 10 and 11 according to embodiments 1 and 2 are configured to set RGB gradation levels for each luminance in advance, RGB gradation levels for the R signal size of the R component in each RGB signal may be set instead of the luminance. The absorption characteristics of light of a long wavelength to many mucous membranes such as blood vessels are lower than those of other G and B components. Therefore, the R signal is not affected by the absorption characteristics of the mucous membrane and is a signal indicating the approximate structure of the mucous membrane surface, and therefore can be used instead of the brightness.

In this way, when the R signal is used instead of the luminance, a configuration for calculating the luminance from the RGB signal can be omitted, and the processing can be simplified. In addition, when the R signal is used instead of the luminance, it is not necessary to set the RGB gradation table for all the values of 0 to 255, and only a part of the values of the R signal among the values of 0 to 255 may be set. In the case of using the R signal instead of the luminance, the R signal subjected to the blurring process may be used.

In the endoscope systems according to embodiments 1 and 2, different RGB gray scales may be provided in the normal light observation mode and the narrow band light observation mode.

Further, in the endoscope systems according to embodiments 1 and 2, the normal image is generated in the normal light observation mode in which the imaging target is irradiated with the normal light, but the image signal of the desired wavelength band may be generated by further performing a predetermined matrix operation on the RGB signal input to the normal light image generating unit 62. Specifically, by performing the above matrix operation, for example, RGB signals as acquired in a narrow-band light observation mode can be generated. As such a matrix operation, a known operation method can be used.

In the endoscope systems according to embodiments 1 and 2, the narrow-band image is generated in the narrow-band light observation mode in which the imaging target is irradiated with the narrow-band light, but the image signal of a desired wavelength band may be generated by further performing a predetermined matrix operation on the RGB signal input to the narrow-band light image generating unit 64. Specifically, by performing the matrix operation, an image signal in the wavelength band of the blue-violet laser beam VL can be generated, for example. As such a matrix operation, a known operation method can be used.

In the endoscope systems 10 and 11 according to embodiments 1 and 2, the description has been given of the case of using narrow-band light including blue narrow-band light (blue laser light and blue-violet laser light) having high light absorption with respect to the absorbing substance of the mucous membrane, but light including green narrow-band light (for example, wavelength components of 540 to 560 nm) having high light absorption with respect to the absorbing substance of the mucous membrane may be used.

Further, in the endoscope systems 10 and 11 according to embodiments 1 and 2, the blue laser light source 34 and the blue-violet laser light source 36 are used as the light sources, and the phosphor 44 is irradiated with the blue laser light to obtain white light, but the configuration of the light source device 14 is not limited thereto, and other configurations are possible.

Specifically, as shown in the endoscope system 15 of fig. 13, the Light source device 14 may include a V-LED (Violet Light Emitting Diode) 42a, a B-LED (Blue Light Emitting Diode) 42B, a G-LED (Green Light Emitting Diode) 42c, and a R-LED (Red Light Emitting Diode) 42D. The light source device 14 further includes a light source control unit 40 that controls the driving of the 4 color LEDs 42a to 42d, and an optical path coupling unit 43 that couples optical paths of the 4 color lights emitted from the 4 color LEDs 42a to 42 d. The light coupled by the optical path coupling portion 43 is irradiated into the subject via the light guide 41.

As shown in FIG. 14, the V-LED42a generates violet light V having a center wavelength of 405 + -10 nm and a wavelength range of 380-420 nm. The B-LED42B generates blue light B with a central wavelength of 460 + -10 nm and a wavelength range of 420-500 nm. The G-LED42c generates green light G with a wavelength range of 480-600 nm. The R-LED42d generates red light R with a center wavelength of 620-630 nm and a wavelength range of 600-650 nm.

The light source control unit 40 turns on the V-LED42a, the B-LED42B, the G-LED42c, and the R-LED42d even in any one of the normal light observation mode, the 1 st narrow-band light observation mode, and the 2 nd narrow-band light observation mode. Therefore, the observation target is irradiated with light obtained by mixing 4 color lights of the violet light V, the blue light B, the green light G, and the red light R. In the normal light observation mode, the light source control unit 40 controls the LEDs 42a to 42d such that the light quantity ratio among the violet light V, blue light B, green light G, and red light R is Vc: Bc: Ge: Rc. On the other hand, in the 1 st and 2 nd narrow band observation modes, the light source control unit 40 controls the LEDs 42a to 42d so that the light amount ratio between the violet light V, blue light B, green light G, and red light R becomes Vs: Bs: Gs: Rs. The 1 st narrow-band light observation mode is used for determining whether or not the sterilization of helicobacter pylori has been successful, and is a mode for displaying the 1 st narrow-band image on the display 18. The 2 nd narrow-band light observation mode is used for determining whether or not the pyloric helicobacter is infected, and is a mode for displaying the 2 nd narrow-band image on the display 18.

Further, although the endoscope systems 10 and 11 according to embodiments 1 and 2 are provided using the synchronous imaging element, the present invention can be applied to an endoscope system of a so-called frame sequential display system.

In the endoscope system of the frame sequential display system, when the normal light observation mode is used, the rotating filter provided with the R (red) filter, the G (green) filter, and the B (blue) filter in the circumferential direction is rotated, and thereby the blue light, the green light, and the red light are sequentially irradiated on the imaging target.

The reflected image from the imaging target irradiated with the blue light, the green light, and the red light is captured by the monochromatic imaging element, and the R signal, the G signal, and the B signal are sequentially output from the imaging element, and the signals are acquired by the image signal acquiring unit 60.

In the narrow-band observation mode, the blue narrow-band light, the green light, and the red light are sequentially irradiated to the imaging object by rotating the rotating filter in which the Bn filter, the G filter, and the R filter that transmit the blue narrow-band light having the center wavelength of 415nm are provided in the circumferential direction.

A reflected image from an imaging target irradiated with blue narrow-band light, green light, and red light is captured by a monochromatic imaging element, and an R signal, a G signal, and a Bn signal are sequentially output from the imaging element, and the signals are acquired by an image signal acquisition unit 60. In addition, the Bn signal is processed in the same manner as the B signal.

The present invention is not limited to an endoscope system including the insertion portion 21 as in the endoscope systems 10 and 11 of embodiments 1 and 2, and can be applied to a capsule endoscope.

Description of the symbols

10. 11, 15-endoscope system, 12-endoscope, 13-universal cord, 14-light source device, 16-processor device, 18-display, 20-input device, 21-insertion section, 22-operation section, 22 a-angle knob, 22 b-mode switch, 22 c-zoom operation section, 23-bending section, 24-tip section, 24 a-illumination optical system, 24 b-image pickup optical system, 34-blue laser source, 36-bluish-violet laser source, 40-light source control section, 41-light guide, 43-light path combining section, 44-phosphor, 45-illumination lens, 46-imaging lens, 47-zoom lens, 48-imaging element, 50-CDS/AGC circuit, 51-gamma conversion section, 52-A/D conversion section, 60-image signal acquisition section, 62B-gradation processing section, 61-interference removal section, 62-normal light image generation section, 64-narrow band light image generation section, 65-display control section, 66-blur processing section, 70, 73-LUT 1 processing section, 71, 74-LUT 2 processing section, 72, 75-luminance calculation section, A-input value, B-input value, BC1, BC2-B gray scale, GC1, GC2-G gray scale, RC1, RC2-R gray scale, RL, BL, GL-straight line, SL-narrow band light, BL-blue laser, FL-fluorescence, VL-blue-violet laser, WL-white light, V-violet light, r-red, G-green, B-blue, 42 a-V-LED, 42B-B-LED, 42c-G-LED, 42 d-R-LED.

Claims

1. An endoscopic image signal processing apparatus comprising:

an image signal acquisition unit that acquires an RGB signal for each pixel obtained by imaging an imaging target using an endoscope; and

a gradation processing section for performing gradation processing on the RGB signals using an RGB gradation table in which input values and output values of RGB are associated with each other,

the RGB gray scale table is set for each brightness or R component size, and is set in such a way that when the RGB signals with the RGB ratio of the 1 st ratio are input into each RGB gray scale table, the output value with the RGB ratio of the 2 nd ratio is output from each RGB gray scale table,

the gradation processing section acquires luminance or R component from the RGB signal, and performs the gradation processing using the RGB gradation table corresponding to the luminance or R component,

the 1 st ratio is an RGB ratio of RGB signals obtained by photographing a normal mucosa.

2. The endoscopic image signal processing apparatus according to claim 1,

the gradation processing unit acquires a luminance or an R component for each pixel constituting the RGB signal, and performs the gradation processing for each pixel.

3. The endoscopic image signal processing apparatus according to claim 1 or 2,

the RGB gray scale table sets only a part of the luminance or the R component size.

4. The endoscopic image signal processing apparatus according to claim 3,

the gradation processing section performs the gradation processing by interpolating an RGB gradation table set for each of the partial luminances or R component sizes.

5. The endoscopic image signal processing apparatus according to claim 1 or 2,

the RGB gray scale table for each of the brightness or R component values maintains the hue when the RGB signal having the RGB ratio of the 1 st ratio is inputted, and outputs an output value in which the lightness and chroma are changed.

6. The endoscopic image signal processing apparatus according to claim 1 or 2,

the endoscope image signal processing device is provided with:

a low-frequency image generation processing unit that generates a low-frequency image by performing low-frequency image generation processing on the RGB signals,

the gradation processing section acquires brightness or an R component from the low-frequency image.

7. The endoscopic image signal processing apparatus according to claim 1 or 2,

the RGB signals are obtained by imaging the imaging object irradiated with illumination light containing narrow-band light.

8. The endoscopic image signal processing apparatus according to claim 7,

the narrow-band light is blue or green narrow-band light.

9. The endoscopic image signal processing apparatus according to claim 1 or 2,

the RGB signals are obtained by imaging a luminal organ as the imaging target.

10. The endoscopic image signal processing apparatus according to claim 1 or 2,

in the RGB gradation tables, the ratio of the R output value to the R input value when the RGB signals obtained by imaging the presence of the red mucous membrane are input is larger than the ratio of the R output value to the R input value when the RGB signals obtained by imaging the normal mucous membrane are input.

11. The endoscopic image signal processing apparatus according to claim 1 or 2,

in the RGB gradation tables, the ratio of the R output value to the R input value when the RGB signals obtained by imaging the atrophic mucosa are input is smaller than the ratio of the R output value to the R input value when the RGB signals obtained by imaging the normal mucosa are input.

12. An endoscopic image signal processing apparatus comprising:

the gradation processing section acquires a luminance or an R component for each pixel constituting the RGB signal, and performs the gradation processing for each pixel using the RGB gradation table according to the magnitude of the luminance or the R component,

13. An endoscopic image signal processing method for acquiring RGB signals for each pixel acquired by imaging an imaging object using an endoscope, and performing gradation processing on the RGB signals using an RGB gradation table in which input values and output values of RGB are associated with each other,

acquiring luminance or R component from the RGB signal, and performing the gradation processing using the RGB gradation table corresponding to the magnitude of the luminance or R component,

14. A storage medium storing an endoscopic image signal processing program for causing a computer to function as an image signal acquisition section and a gradation processing section,

an image signal acquisition unit acquires RGB signals for each pixel obtained by imaging an imaging object using an endoscope,

the gradation processing section performs gradation processing on the RGB signals using an RGB gradation table in which input values and output values of RGB are associated with each other,

the storage medium storing the endoscope image signal processing program is characterized in that,