Endoscope processor and endoscope system

Abstract

To provide an endoscope device 1 which can be applied to many subjects and the like.SOLUTION: An endoscope device 1 includes: an endoscope 10 having an imaging unit 15; an image processing circuit 31 for generating an image of a subject; a calculation circuit 32 for standardizing a total of a red pixel value and a green pixel value of the pixels in the image of the subject by the value twice of a green pixel value and calculating the index; a memory 50 for storing a plurality of threshold values for identifying a plurality of regions of the subject into three or more types of symptom levels and an identification color corresponding to the symptom levels; an identification circuit 33 for identifying the symptom level from the index; an identification color acquiring circuit 34 for acquiring the identification colors corresponding to the symptom levels; an image generating circuit 35 for generating an identification image using the identification colors; and a monitor 40 for displaying the identification images.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an endoscope device for imaging a subject inside the body.

Background Art

[0002] International Publication No. 2018 / 230130 discloses an endoscope device that calculates an index indicating the degree of abnormality of a subject according to the color included in the subject image captured by the endoscope, and discriminatively displays the index according to a threshold value.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, in the above-described endoscope device, the degree of abnormality indicated by the index is either abnormal or normal. In addition, since the setting of the threshold value for discriminating the index is simple, there is a risk that applicable subjects and the like are limited.

[0004] An object of the present invention is to provide an endoscope device that discriminatively displays according to three or more symptom levels. Another object of the present invention is to provide an endoscope device applicable to many subjects and the like.

Means for Solving the Problems

[0005] The endoscope apparatus according to an embodiment of the present invention includes an endoscope having an imaging unit that images at least any subject in the body of a subject and outputs an image signal, an image processing unit that performs image processing on the image signal to generate a subject image, and a calculation unit that calculates an index for each of a plurality of pixels in at least a partial region of the subject image by normalizing the sum of a red pixel value and a green pixel value of each of the plurality of pixels by a value twice the blue pixel value, a memory that stores a plurality of threshold values for identifying a plurality of regions of the subject into any of three or more symptom levels and an identification color corresponding to each of the plurality of symptom levels, an identification unit that identifies the symptom level of each of the pixels using the plurality of threshold values based on the index, an identification color acquisition unit that acquires the identification color corresponding to the symptom level of each of the pixels, an image generation unit that generates an identification image using the identification color of each of the plurality of pixels, and a monitor that displays the identification image.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide an endoscope apparatus that performs identification display according to three or more symptom levels. Further, according to the present invention, it is possible to provide an endoscope apparatus applicable to many subjects and the like.

Brief Description of the Drawings

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MODE FOR CARRYING OUT THE INVENTION

[0008] <Configuration of Endoscope Apparatus> As shown in FIG. 1, the endoscope apparatus 1 according to the embodiment includes an endoscope 10, a light source device 20, a processor 30, a monitor 40, and a memory 50.

[0009] The endoscope 10 has a long and slender insertion portion 11 to be inserted into a subject 90, an operation portion 12 provided at the proximal end of the insertion portion 11, a universal cord 13 extending from the operation portion 12, and a connector 14. The operation portion 12 has a plurality of buttons 12A and the like which are an endoscope setting portion for operating the endoscope function and the imaging function. The insertion portion 11 of the endoscope 10 has, in order from the distal end side, a distal end portion 11A, a bending portion 11B provided at the proximal end of the distal end portion 11A, and a long and slender flexible tube 11C provided at the proximal end of the bending portion 11B. The distal end portion 11A is provided with an imaging unit 15 which is an imaging portion and an illumination unit 16 which is an illumination portion.

[0010] The connector 14 of the endoscope 10 is connected to the light source device 20 and the processor 30. The illumination light L generated by the light source device 20 is guided to the illumination unit 16 at the distal end 11A of the insertion section 11 to illuminate the subject 91 inside the body of the subject 90. The imaging unit 15 has an imaging element such as a CCD. The imaging unit 15 converts the reflected light R from the subject 91 into an electrical signal and outputs the subject image to the processor 30.

[0011] The light source device 20 includes a light source control unit 22, a light source 23, and a multiplexer 24.

[0012] The light source control unit 22 is a light source control circuit that is connected to the light source 23 and controls the light source 23 according to a control signal from the processor 30.

[0013] The light source 23 has a plurality of light emitting elements such as LEDs, for example. The light source 23 has an R element 23R, a G element 23G, and a B element 23B. The R element 23R emits red light Br in a normal band. The G element 23G emits green light Bg in a normal band. The B element 23B emits blue light Bb in a normal band. The B element 23B not only emits blue light Bb in a normal band, but also outputs narrow-band blue light Nb by narrowing the blue light with, for example, a narrow-band optical filter (not shown).

[0014] The multiplexer 24 multiplexes a plurality of lights input from the light source 23 and outputs the illumination light L to the illumination unit 16.

[0015] The processor 30 includes an image processing unit 31, a calculation unit 32, an identification unit 33, an identification color acquisition unit 34, an image generation unit 35, and a setting unit 36. The processor 30 composed of a CPU controls the entire endoscope apparatus 1, generates an endoscope image based on the imaging signal input from the endoscope 10, and generates an identification image based on the endoscope image, as will be described later.

[0016] The setting unit 36, which is a setting circuit, is a button or the like for the user to input various instructions. The setting unit 36 may also be a touch panel, a keyboard, a foot switch, the button 12A of the endoscope 10, etc., which are separate from the processor 30. For example, from the setting unit 36, instructions such as the bending instruction of the bending part, the driving instruction of the light source device 20, the type of the illumination light L for illuminating the subject 91, the type of the observation site of the subject 91, the image to be displayed on the monitor 40, etc. are input.

[0017] Note that the configurations of the image processing unit 31, the calculation unit 32, the identification unit 33, the identification color acquisition unit 34, and the image generation unit 35 will be described later.

[0018] At least any one of the plurality of configurations of the processor 30, and the light source control unit 22 may be configured by the processor 30 that operates by software (program) or the internal circuit (CPU) of the light source device, or may be configured by a dedicated hardware circuit.

[0019] The monitor 40 is, for example, a liquid crystal or a CRT that displays a color image. The monitor 40 displays the image instructed by the processor 30. The monitor 40 having the function of a touch panel may also constitute a part of the setting unit 36.

[0020] The memory 50 is a RAM, a ROM, or a hard disk drive device or the like that stores data such as the operating conditions of the processor 30, programs, etc. The memory 50 may also be the internal memory of the processor 30 in which data, etc. are transferred and stored from a non-temporary computer-readable storage medium such as a CD, a DVD. The processor 30 performs predetermined processing based on the programs and data stored in the memory 50. Also, past examination data of the subject 90 stored in, for example, a server, which is separate from the endoscope device 1, may be transferred to the memory 50 via the Internet line or the like.

[0021] <Indicator> The calculation unit 32 is a calculation circuit that calculates an index VI for each of a plurality of pixels of a subject image output by the imaging unit. The index VI that quantitatively indicates the symptom level of the subject 91 is calculated using a predetermined calculation formula.

[0022] Hereinafter, the process of selecting the calculation formula will be described. FIG. 2 is a diagram for explaining the relationship between the absorption characteristic W of plasma and the wavelength of the light generated by the light source 23. In FIG. 2, red light Br in the normal band, green light Bg in the normal band, blue light Bb in the normal band, narrow-band blue light Nb, the absorption characteristic W of plasma, and the peak wavelength Wp of the plasma absorption coefficient are shown.

[0023] As shown in FIG. 2, the absorption characteristic W of plasma is low near a wavelength of 415 nm, peaks near a wavelength of 465 nm, and approaches 0 near a wavelength of 550 nm.

[0024] Therefore, the blue light Bb may be in the normal band, but in order to significantly detect plasma, it is particularly preferable that the blue light Bb is narrowed so that the center wavelength is the same as the peak wavelength Wp of the plasma absorption coefficient. For example, the blue light Bb is narrowed so that the center wavelength is near 465 nm and is used as the narrow-band blue light Nb. The blue light Bb may be narrowed so that the center wavelength is 460 nm to 470 nm. Further, the blue light Bb may be narrowed so that the center wavelength is 415 nm to 495 nm.

[0025] When special light including red light Br, green light Bg, and narrow-band blue light Nb is irradiated, plasma absorbs more blue light with respect to red light and green light, and appears more yellowish than when normal light including normal blue light Bb is irradiated.

[0026] Next, FIG. 3 schematically shows a cross-section of the mucosa. In FIG. 3, normal mucosa N, edema M, polyp S, blood vessel Bv, and illumination light L are shown. Here, the illumination light L is short-wavelength monochromatic light such as narrow-band blue light Nb. The pigment in the mucosa is plasma.

[0027] As shown in the light penetration region L1, in normal mucosa N, the penetration degree of illumination light L is high, and due to the mucosal pigment with a high absorption coefficient on the short-wavelength side rather than the long-wavelength side, the reflected light R appears light yellow.

[0028] As shown in the light penetration region L2, in edema M, the penetration degree of illumination light L is lower than that in normal mucosa N. More specifically, in edema M, the illumination light L is scattered more on the short-wavelength side than on the long-wavelength side by the hypertrophied epithelium and is reflected without being absorbed by the mucosal pigment. Therefore, in edema M, the reflected light R appears whiter than in normal mucosa N.

[0029] As shown in the light penetration region L3, in polyp S, the light penetration degree is further reduced compared to edema M, and the reflected light R appears even whiter than in edema M.

[0030] Figure 4 shows the index VI in which the green pixel value Vg, red pixel value Vr, blue pixel value Vb, or the sum of the green pixel value Vg and the red pixel value Vr included in the endoscopic image is normalized respectively. The pixel value V is acquired, for example, as 8-bit data (0 - 255).

[0031] Figure 4 shows the difference in the index VI due to the difference in the calculation formula of the index VI among normal mucosa N, edema M, and polyp S. In Figure 4, each of "Vg / Vb", "Vr / Vb", "Vr / Vg", and "(Vr + Vg) / 2Vb" on the X-axis represents the calculation formula of the index VI, and the Y-axis represents the index VI normalized by each calculation formula.

[0032] The solid line indicates normal mucosa N, the dashed line indicates edema M, and the dotted-dashed line indicates polyp S. Hereinafter, edema M and polyp S are referred to as abnormal mucosa.

[0033] In the mucous membranes in the body, for example, the mucous membranes of the nasal sinuses, the symptom level becomes more severe in the order of normal mucous membrane N, edema M, and polyp S. There is a difference in color between the normal mucous membrane N and the abnormal mucous membrane. As the symptom level becomes more severe, the mucous membrane epithelium becomes thicker and the whiteness in appearance also becomes stronger. Therefore, the calculation formula with the largest index VI for the normal mucous membrane N and the polyp S is "(Vr + Vg) / 2Vb".

[0034] Figure 5 shows the index VI of edema M and polyp S, which are normalized by the normal mucous membrane N, for the same edema M and polyp S as in Figure 4. In Figure 5, the X-axis shows the calculation formula of index VI used for calculating the normalized index VIN by the normal mucous membrane N, and the Y-axis shows the index VIN.

[0035] As shown in Figures 4 and 5, for the normal mucous membrane N and the polyp S, the indices VI and VIN calculated by the calculation formula "(Vr + Vg) / 2Vb" are larger than the indices VI and VIN calculated by other index calculation formulas.

[0036] That is, the index VIN calculated by the calculation formula "(Vr + Vg) / 2Vb" greatly represents the difference in color between the normal mucous membrane N and the abnormal mucous membrane.

[0037] <Operation method of the endoscope device> The operation method of the endoscope device 1 will be described using the flowchart of Figure 6.

[0038] <Step S10: Illumination light irradiation> The insertion part 11 of the endoscope 10 is inserted into the living body of the subject 90, for example, the nasal cavity. The illumination light L from the light source device 20 is irradiated onto the mucous membrane, which is the subject 91, via the illumination unit 16 at the tip 11A. The illumination light L is red light Br, green light Bg, and blue light Bb.

[0039] <Step S20: Imaging signal output> The imaging unit 15 at the tip 11A receives the reflected light R from the subject 91, converts it into an electrical signal, and outputs the imaging signal to the processor 30.

[0040] <Step S30> Image Processing The image processing unit 31 is an image processing circuit that generates an endoscopic image, which is a subject image, by performing image processing such as gain adjustment, white balance adjustment, gamma correction, contour enhancement correction, and enlargement / reduction adjustment based on the imaging signal.

[0041] <Step S40> Index Calculation The calculation unit 32 calculates the index VI of each pixel by normalizing the sum of the red pixel value Vr and the green pixel value Vg of each of the plurality of pixels of the subject image by a value twice the blue pixel value Vb(Nb). In other words, the calculation unit 32 calculates the index VI of a plurality of regions (pixels) of the subject.

[0042] In FIGS. 4 and 5, “(Vr + Vg) / 2Vb” was used as the calculation formula for normalizing the pixel value and calculating the index V. However, any calculation formula that normalizes the sum of the red pixel value and the green pixel value by a value twice the blue pixel value can be appropriately changed.

[0043] For example, the index VI may be converted into 8-bit (0 - 255) data, a numerical value may be further added to the 8-bit data, or the k value of the calculation formula “(Vr + Vg) / kVb” may be changed. Hereinafter, the index VI was calculated using Equation 1.

[0044] <Equation 1> VI = 32 × log 2 [(Vr + Vg) / 2Vb] + 256

[0045] The calculation unit 32 preferably calculates the index VI using any one of a plurality of calculation formulas corresponding to each of the plurality of subjects 91 (for example, paranasal sinuses, digestive tract).

[0046] <Step S50> Symptom Level Identification The identification unit 33 is an identification circuit that identifies the symptom level of each pixel based on the index VI using a plurality of threshold values T.

[0047] In the endoscope device 1, the symptom levels are five types: "normal / mild / moderate / severe / critical". If there are three or more symptom levels, it is easier to judge detailed symptoms than in the case of two types, "normal / abnormal".

[0048] To identify the five types of symptom levels, four thresholds T (the first threshold T1 for distinguishing normal and mild, the second threshold T2 for distinguishing mild and moderate, the third threshold T3 for distinguishing moderate and severe, and the fourth threshold T4 for distinguishing severe and critical) are required. The thresholds T are appropriately set in advance based on the judgments of multiple identifiers. Needless to say, the magnitude relationship of the four thresholds T set within a predetermined range is in the order of T1 - T4.

[0049] Fig. 7 shows an example of the threshold T. It is preferable that the differences ΔT between the multiple thresholds are substantially the same. For example, the difference ΔT34 (threshold T4 - threshold T3) is preferably 80% or more and 120% or less of the difference ΔT23 (threshold T3 - threshold T2).

[0050] However, depending on the conditions, the first threshold difference ΔT1 between the first threshold T1 and the second threshold T2 may be larger than the second threshold difference ΔT2 between the second threshold T2 and the third threshold T3, and the second threshold difference ΔT2 may be larger than the third threshold difference ΔT3 between the third threshold T3 and the fourth threshold T4. Conversely, the first threshold difference ΔT1 may be smaller than the second threshold difference ΔT2, and the second threshold difference ΔT2 may be smaller than the third threshold difference ΔT3.

[0051] Also, depending on the system to be combined or the imaging element to be mounted, etc., the threshold difference ΔT may increase as the severity increases.

[0052] Note that the memory 50 stores a plurality of threshold sets, each of which consists of a plurality of thresholds, corresponding to each of the plurality of subjects 91, and the identification unit 33 identifies using the threshold set corresponding to the subject 91. The threshold set used by the identification unit 33 may be automatically acquired or may be set by the setting unit 36.

[0053] As shown in FIG. 8, each threshold value T (T1 - T4) included in the plurality of threshold value sets has a variation (dispersion), but the variation of each threshold value T (T1 - T4) is preferably set within a predetermined range. For example, the maximum value of the threshold value T1 is 302, and the minimum value of the threshold value T1 is 280. In contrast, the maximum value of the threshold value T4 is 270, and the minimum value is 264. That is, the variation LT1 of the threshold value T4 is smaller than the variation LT2 of the threshold value T1.

[0054] The cause is the color balance calibration by the image processing unit 31. That is, because the image processing unit 31 performs white balance with white close to the color of the most severe area as a reference for color balance calibration.

[0055] It is possible to adjust the variation of the threshold value T by changing the color used for color balance calibration or by performing calibration using multiple colors. For example, by performing color balance calibration using the color of the normal area (red - yellow), the variation LT2 of the threshold value T1 can be reduced. Also, by performing color balance calibration using an intermediate color between the color of the most severe area and the color of the normal area (red - yellow), the variations of the plurality of threshold values T can be reduced and averaged.

[0056] <Step S60> Identification color acquisition unit The identification color acquisition unit 34 acquires an identification color corresponding to the symptom level of the pixel acquired by the identification unit 33.

[0057] FIG. 9 shows the identification colors corresponding to the symptom levels. The index VI is data in the range of (0 - 511) obtained by adding 256 to 8 - bit data, for example. The plurality of threshold values T and the identification colors are stored in the memory 50.

[0058] In the example of FIG. 9, the identification color acquisition unit 34 acquires a plurality of colors with different hues, but a plurality of saturations with different vividness, a plurality of brightnesses with different brightness, a plurality of hatchings with different intervals, or a plurality of patterns with different patterns may be acquired.

[0059] Note that the endoscopic image may include pixels having color error pixel values that do not occur in normal imaging. In the endoscope apparatus 1, a pixel in which at least one of the red pixel value, the green pixel value, and the blue pixel value is a pixel value V equal to or less than a predetermined lower limit pixel value or equal to or greater than a predetermined upper limit pixel value is defined as a first error pixel. For example, a pixel having a pixel value V in the range of (0 - 255) and having a pixel value of 5 or less or 250 or more is a first error pixel.

[0060] Furthermore, a pixel of the index VI that is equal to or less than a predetermined lower threshold value or equal to or greater than a predetermined upper threshold value is defined as a second error pixel. For example, in the example shown in FIG. 9, a pixel in which the index VI is equal to or less than the lower threshold value of 10 or equal to or greater than the upper threshold value of 500 is a second error pixel.

[0061] The identification color acquisition unit 34 acquires an error color for the error pixels (the first error pixel and the second error pixel). The image generation unit generates an identification image using the error color for the error pixels. The error color is not limited to white / black illustrated in FIG. 9, and may be, for example, gray or the like. Also, the color of pixels with a threshold value or less and a threshold value or more may be the same error color. The numerical values of the determination criteria for the error pixels and the data of the error color are stored in the memory 50.

[0062] <Step S70> Identification Image Generation The identification color acquisition unit 34 acquires an identification color corresponding to the symptom level of each pixel. The image generation unit 35 is an identification color acquisition circuit that generates an identification image using the identification colors of the respective pixels of the plurality of pixels.

[0063] <Step S80> Display The monitor 40 displays the identification image.

[0064] Fig. 10 shows an example of the display image on the monitor 40. In Fig. 10, a partial area of the endoscope image 40A shown in color is replaced with the identification image 40B and displayed. In other words, a superimposed image in which the identification image 40B is superimposed on the endoscope image 40A is displayed. The range displayed as the identification image 40B in the endoscope image 40A is indicated by a frame.

[0065] From the viewpoints of visibility and operability, it is preferable that the area of the identification image 40B is 20% or more and 70% or less of the area of the entire area of the endoscope image 40A. The area of the identification image 40B can be changed, for example, by operating the setting unit 36.

[0066] In addition, on the monitor 40, the average value 40D of the indicators is displayed together with the identification color list display 40C. That is, the calculation unit 32 calculates the average value 40D of the indicators of a plurality of pixels, and the monitor 40 displays the average value 40D of the indicators.

[0067] Based on the average value 40D of the indicators, the user can easily grasp the symptoms of the subject.

[0068] As shown in Fig. 11, the identification image 40B may be displayed on the monitor 40 instead of the endoscope image 40A. That is, the calculation unit 32 may calculate an index from a plurality of pixels in the entire area of the endoscope image 40A which is the subject image, and the image generation unit 35 may generate an identification image corresponding to the entire area of the endoscope image 40A.

[0069] Also, as shown in Fig. 12, the identification image 40B of the area surrounded by a frame in the endoscope image 40A may be displayed in an area different from the endoscope image 40A on the monitor 40. At least either the position or the range (area) of the partial area for generating the identification image 40B in the entire area of the endoscope image 40A which is the subject image can be appropriately selected by operating the setting unit 36.

[0070] In a narrow pipeline, it may not be easy to direct the center of the endoscopic image 40A (the center of the field of view of the imaging unit 15) toward the region of interest. However, by selecting at least one of the position and range of the region where the identification image 40B is displayed, the user can easily identify the region of interest.

[0071] As shown in FIG. 13, on the monitor 40, together with the endoscopic image 40A and the identification image 40B, an identification image 40BP in a range similar to the identification image 40B during the subject 90's past examination, and the average value 40DP of the index may be displayed. The display screen of the endoscopic image 40A and the identification image 40B during the examination and the display screen of the past endoscopic image and the identification image 40BP may be switched and displayed on the monitor 40B, or may be displayed on separate monitors. It is preferable that the display range and display position of the past identification image 40BP can be appropriately changed. The identification image 40BP etc. during the subject 90's past examination are stored, for example, in a server in the hospital and transferred to the processor 30.

[0072] As described above, the operation method of the endoscopic system according to another embodiment is The imaging unit 15 of the endoscope 10 images the subject 91 inside the body of the subject 90 and outputs an image signal, The processor 30 performs image processing on the image signal to generate a subject image, and normalizes the sum of the red pixel value and the green pixel value of each of the plurality of pixels in at least a part of the region of the subject image by a value twice the blue pixel value, thereby calculating the index of each pixel, stores a plurality of thresholds for identifying the plurality of regions of the subject into any one of three or more symptom levels, and an identification color corresponding to each of the plurality of symptom levels, identifies the symptom level of each pixel using the plurality of thresholds based on the index, obtains the identification color corresponding to the symptom level of each pixel, and generates an identification image using the identification color of each of the plurality of pixels. The monitor 40 displays the identification image.

[0073] The program of another embodiment causes a computer to execute the above processing.

[0074] A non-transitory computer-readable storage medium of another embodiment stores a program that causes a computer to execute the above processing.

[0075] Note that the numerical ranges described above, for example, the wavelength, are not limited to the ranges described above and can be increased or decreased as appropriate. Also, the insertion portion 3 of the endoscope 9 may be a rigid endoscope. The present invention is not limited to the above-described embodiments and the like, and various changes and modifications can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0076] 1 ·· Endoscope apparatus 3 ·· Insertion portion 9 ·· Endoscope 10 ·· Endoscope 11 ·· Insertion portion 11A ·· Tip portion 11B ·· Bending portion 11C ·· Flexible tube 12 ·· Operation portion 12A ·· Button 13 ·· Universal cord 14 ·· Connector 15 ·· Imaging unit 16 ·· Lighting unit 20 ·· Light source device 22 ·· Light source control unit (light source control circuit) 23 ·· Light source 23B ·· B element 23G ·· G element 23R ·· R element 24 ·· Combiner 30 ·· Processor 31 ·· Image processing unit (image processing circuit) 32 ·· Calculation unit (calculation circuit) 33 ·· Identification unit (identification circuit) 34 ·· Identification color acquisition unit (identification color acquisition circuit) 35 ·· Image generation unit (image generation circuit) 36 ·· Setting unit 40··Monitor 40A··Endoscopic image 40B, 40BP··Identification image 40C··List display of identification colors 40D··Average value 50··Memory 90··Subject 91··Object

Claims

1. An image processing unit that generates a subject image from an image signal; a calculation unit that calculates an index of one or more pixels of the object image by normalizing a sum of a red pixel value and a green pixel value of the one or more pixels by a blue pixel value; a classification unit that classifies the symptom level of the pixel based on the index using a plurality of thresholds for classifying the symptom level into one of a plurality of types of symptom levels; a discrimination color acquisition unit that acquires a discrimination color corresponding to the symptom level; an image generating unit that generates an identification image by applying the identification color to the pixels.

2. 2. The endoscope processor according to claim 1, wherein the plurality of symptom levels are normal, mild, moderate, severe, and very severe.

3. The endoscope processor according to claim 1 , wherein each of the plurality of thresholds is set within a predetermined range.

4. The endoscope processor according to claim 1 , wherein the differences between the plurality of threshold values ​​are substantially the same.

5. The endoscope processor according to claim 2, characterized in that a first threshold difference between a first threshold for distinguishing between the normal and the mild condition and a second threshold for distinguishing between the mild and the moderate condition is greater than a second threshold difference between the second threshold and a third threshold for distinguishing between the moderate and the severe condition, and the second threshold difference is greater than a third threshold difference between the third threshold and a fourth threshold for distinguishing between the severe and the most severe condition.

6. The endoscope processor according to claim 2, characterized in that a first threshold difference between a first threshold for distinguishing between the normal and the mild condition and a second threshold for distinguishing between the mild and the moderate condition is smaller than a second threshold difference between the second threshold and a third threshold for distinguishing between the moderate and the severe condition, and the second threshold difference is smaller than a third threshold difference between the third threshold and a fourth threshold for distinguishing between the severe and the most severe condition.

7. The endoscope processor according to claim 2 , wherein the identification unit acquires a plurality of threshold sets including the plurality of thresholds corresponding to a plurality of subjects, respectively.

8. The endoscope processor according to claim 7, characterized in that the variation in the thresholds that distinguish between the severe condition and the most severe condition among the plurality of thresholds in the plurality of threshold sets is smaller than the variation in the thresholds that distinguish between the normal condition and the mild condition.

9. 9. The endoscope processor according to claim 8, wherein the image processing unit performs white balance adjustment using white as color balance calibration.

10. 8. The endoscope processor according to claim 7, wherein the variation in the threshold is controlled by a color used in color balance calibration.

11. The endoscope processor according to claim 10, wherein the image processing unit performs color balance calibration by adjusting the color using an intermediate color between the color of the normal area and the color of the most severe area.

12. The endoscope processor according to claim 1 , wherein the calculation unit calculates the index using one of a plurality of calculation formulas corresponding to each of a plurality of subjects.

13. The distinguishing color acquisition unit acquires an error color, the error color is a color applied to a first error pixel in which at least one of the red pixel value, the green pixel value, and the blue pixel value is equal to or less than a predetermined lower limit pixel value or equal to or more than a predetermined upper limit pixel value, and to a second error pixel in which the index is equal to or less than a predetermined lower limit threshold value or equal to or more than a predetermined upper limit threshold value; The endoscope processor according to claim 1 , wherein the image generating section generates the identification image by using the error color for the first error pixel and the second error pixel.

14. The endoscopic processor described in Claim 1, characterized in that the image generation unit outputs, together with the identification image, a past image which is an identification image generated based on a past subject image taken of the same subject.

15. An endoscope processor according to claim 1; an endoscope connected to the endoscope processor; a memory connected to the endoscope processor; a monitor connected to the endoscope processor; the endoscope outputs the image signal; The endoscope system is characterized in that the memory stores the threshold value and the distinguishing color.

Images