JP2023001354A - Medical image processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical image processing device that creates an image with an emphasized difference in color between abnormal and normal areas.

SOLUTION: A signal converter converts a first RGB signal into a second RGB signal through color information conversion. In a first quadrant of a first ab space composed of a first element resulting from Lab conversion of the first RGB signal and a second ab space composed of a second element resulting from color information conversion of the first element, a first range, a second range, and a third range are distributed. A difference D12y is a difference in chroma and hue and becomes greater than a difference D12x through the color information conversion. A difference D13y is a difference in hue and becomes greater than a difference D13x through the color information conversion. The color information conversion renders the first range in the second ab space different from the first range in the first ab space in chroma and/or hue.

SELECTED DRAWING: Figure 6

COPYRIGHT: (C)2023,JPO&INPIT

Description

Applied for application of Article 30, Paragraph 2 of the Patent Law Presented at the 20th Annual Meeting of the Japanese Helicobacter Society held at Station Conference Tokyo on June 28, 2014

The present invention relates to a medical image processing apparatus that generates an image that emphasizes the color difference between a normal area and a lesion area.

In the medical field, diagnosis using an endoscope system including a light source device, an endoscope, and a processor device is widely performed. In this endoscope system, an endoscope irradiates an observation target with illumination light, and an imaging device of the endoscope captures an image of the observation target illuminated by the illumination light. image on the monitor. The doctor detects the presence or absence of a lesion while looking at the image displayed on the monitor.

Here, it is possible to easily detect a lesion whose shape and size are significantly different from those of a normal portion, such as a lesion that greatly protrudes from the surface of the mucous membrane. However, lesions whose shape and size are almost the same as normal areas are detected based on the difference in color from normal areas. In this case, if the lesion has not advanced so far and there is almost no difference in color from the normal area, it will be extremely difficult to detect it.

Therefore, in Patent Document 1, processing is performed to further deviate from the reference value for portions where the blood volume (hemoglobin index) deviates from the reference value, thereby clarifying the color difference between the normal portion and the lesion portion. ing.

Japanese Patent No. 3228627

Among lesions, gastric cancer is known to cause atrophy in the gastric mucosa and cause the gastric mucosa to fade. Therefore, the atrophied part where the mucosa is atrophied has a different color than the normal part where the mucous membrane is not atrophied. The presence of stomach cancer is diagnosed by observing the difference in color with an endoscope. .

Here, when atrophy progresses to a high degree (for example, when it is included in group C or D in ABC screening), the difference in color between normal and atrophied parts is clear, so the atrophied part can be easily detected. It is possible to However, when atrophy is progressing (for example, when it is included in group B or C in ABC screening), the difference in color between the atrophic part and the normal part is slight, so the color difference alone can is difficult to detect. Therefore, even if the difference in color between the atrophic portion and the normal portion is slight, such as during the progress of atrophy, the atrophic portion can be easily detected by emphasizing the color difference between the normal portion and the atrophic portion. are required to do so.

It is conceivable to emphasize the color difference between the atrophic part and the normal part by the method of Patent Document 1. However, the color of the atrophic part is affected not only by the blood volume but also by factors other than the blood volume.

SUMMARY OF THE INVENTION An object of the present invention is to provide a medical image processing apparatus that generates an image that emphasizes the difference in color between an abnormal portion such as an atrophied portion of the gastric mucosa and a normal portion.

A medical image processing apparatus according to the present invention includes a signal conversion unit that converts a first RGB signal into a second RGB signal through color information conversion processing, and a first element a ^* _x obtained by Lab-converting the first RGB signal. , b ^* _x, and the second elements a ^* _y and b ^* _y obtained after color information conversion processing for the first elements a ^* _x and b ^* _x. A first range, a second range, and a third range are distributed in the secondab space. The difference D12x between the first range and the second range in the 1ab space is greater than the difference D12x between the first range and the second range in the 1ab space, and the difference D13y between the first range and the third range in the 2ab space is the first The difference D13x between the range and the third range is greater than the difference D13x, and the color information conversion process makes the first range in the secondab space different from the first range in the firstab space in at least one of saturation and hue. , the difference D12x is a saturation difference, the difference D13x is a hue difference, the difference D12y is a saturation and hue difference, and the difference D13y is a hue difference.

The first range, the second range, and the third range are preferably observation targets within the subject. In the color information conversion process, each of the first range, the second range, and the third range distinguished by hue and saturation corresponds to the first range, the second range, and the third range before conversion. It is preferable that the processing is to transfer to the first range, the second range, and the third range of the attached conversion destination. The color information conversion process includes, in a space converted into polar coordinates, the first range, the second range, and the , and the third range are preferably transferred to the first range, the second range, and the third range of the conversion destination that are associated with each other.

It is preferable to provide a light source device that emits blue light, green light, and red light, at least one of which is narrowband light, toward the subject. Blue light, green light, and red light are preferably obtained by transmitting light with a wavelength range from blue to red through each filter of the rotating filter. The light whose wavelength ranges from blue to red is preferably light emitted from a xenon lamp or a white LED.

The light source device preferably has a blue semiconductor light source that emits blue light, a green semiconductor light source that emits green light, and a red semiconductor light source that emits red light. It is preferable that the blue light, the green light, and the red light are alternately applied to the subject, and the subject is imaged by a monochrome imaging sensor.

A mode switching unit for switching between a plurality of observation modes each having a different type of image to be displayed on the display unit, wherein at least one of the plurality of observation modes selects an image that has undergone color information conversion processing on the display unit. preferably displayed on

According to the present invention, it is possible to generate an image that emphasizes the difference in color between an abnormal portion such as an atrophied portion of the gastric mucosa and a normal portion.

1 is an external view of an endoscope system according to a first embodiment; FIG. 2 is a block diagram showing functions of the endoscope system of the first embodiment; FIG. 4 is a graph showing emission spectra of violet light V, blue light B, green light G, and red light R; 4 is a block diagram showing functions of a first special image processing unit; FIG. FIG. 4 is an explanatory diagram showing first color information conversion processing for signal ratio space; FIG. 10 is an explanatory diagram showing first color information conversion processing for the ab space; It is an explanatory view showing the first process. 4 is a graph showing the relationship between radius r and radius Er. FIG. 10 is an explanatory diagram showing actions and effects obtained by the first processing for the signal ratio space; It is explanatory drawing which shows the effect|action and effect obtained by the 1st process for ab space. FIG. 11 is an explanatory diagram showing a second process for signal ratio space; It is a graph which shows the movement range of angle (theta) within angle change range R2. 10 is a graph showing the relationship between the angle θ and the angle Eθ after the second processing for the signal ratio space; FIG. 9 is an explanatory diagram showing actions and effects obtained by the second processing for the signal ratio space; It is explanatory drawing which shows the effect|action and effect obtained by the 2nd process for ab space. FIG. 10 is an explanatory diagram showing second color information conversion processing for signal ratio space; FIG. 10 is an explanatory diagram showing second color information conversion processing for the ab space; FIG. 11 is an explanatory diagram showing a third process for signal ratio space; It is a graph which shows the movement range of angle (theta) within angle change range R3. 10 is a graph showing the relationship between the angle θ and the angle Eθ after the third processing for the signal ratio space; FIG. 10 is an explanatory diagram showing actions and effects obtained by the third processing for the signal ratio space; It is explanatory drawing which shows the effect|action and effect obtained by the 3rd process for ab space. FIG. 10 is an image diagram of a monitor that simultaneously displays a first special image and a second special image; It is a flow chart which shows a series of flows of the present invention. FIG. 3 is a block diagram showing functions of a first special image processing section having a first color information conversion section for CrCb space; FIG. 4 is an explanatory diagram showing first color information conversion processing for CrCb space; FIG. 10 is an explanatory diagram showing second color information conversion processing for CrCb space; FIG. 4 is an explanatory diagram showing the first processing for CrCb space; FIG. 11 is an explanatory diagram showing a second process for CrCb space; FIG. 10 is an explanatory diagram showing a third process for CrCb space; FIG. 4 is a block diagram showing functions of a first special image processing section having a first color information conversion section for HS space; FIG. 10 is an explanatory diagram showing first color information conversion processing for HS space; FIG. 10 is an explanatory diagram showing second color information conversion processing for the HS space; FIG. 4 is an explanatory diagram showing first processing for HS space; FIG. 11 is an explanatory diagram showing second processing for HS space; FIG. 11 is an explanatory diagram showing third processing for HS space; It is a block diagram which shows the function of the endoscope system of 2nd Embodiment. 4 is a graph showing an emission spectrum of white light; 4 is a graph showing an emission spectrum of special light; FIG. 11 is a block diagram showing functions of an endoscope system according to a third embodiment; FIG. FIG. 4 is a plan view showing a rotating filter; FIG. 11 is a diagram showing functions of a capsule endoscope system according to a fourth embodiment; FIG. 4 is a graph showing emission spectra of violet light V, blue light B, green light G, and red light R, which are different from those in FIG. Positions of the second range and the third range on the first signal ratio space when the 1B image signal is a narrowband signal and position of the second range and the third range on the first signal ratio space when the 1B image signal is a wideband signal It is explanatory drawing which shows the position of the 2nd range and the 3rd range.

[First embodiment]
As shown in FIG. 1 , the endoscope system 10 of the first embodiment has an endoscope 12 , a light source device 14 , a processor device 16 , a monitor 18 (display section), and a console 19 . The endoscope 12 is optically connected to the light source device 14 and electrically connected to the processor device 16 . The endoscope 12 includes an insertion portion 12a to be inserted into the subject, an operation portion 12b provided at the proximal end portion of the insertion portion 12a, a bending portion 12c and a distal end portion 12d provided at the distal end side of the insertion portion 12a. have. By operating the angle knob 12e of the operation portion 12b, the bending portion 12c is bent. Along with this bending action, the distal end portion 12d is directed in a desired direction.

Further, the operation unit 12b is provided with a mode switching switch 13a in addition to the angle knob 12e. The mode switching SW 13a is used for switching operation between four types of modes: a normal observation mode, a first special observation mode, a second special observation mode, and a simultaneous observation mode. The normal observation mode is a mode in which normal images are displayed on the monitor 18 . The first special observation mode is used to observe the boundary between an atrophied portion of the gastric mucosa caused by a lesion such as gastric cancer and a normal portion, and displays a first special image on the monitor 18 . The second special observation mode is used to observe the difference in color between the atrophic part and the normal part, and is a mode in which a second special image is displayed on the monitor 18 . The simultaneous observation mode is used to simultaneously observe the boundary between the atrophic part and the normal part and the difference in color between the atrophic part and the normal part. This is a mode for simultaneous display.

Processor unit 16 is electrically connected to monitor 18 and console 19 . The monitor 18 outputs and displays image information and the like. The console 19 functions as a UI (User Interface) that receives input operations such as function settings. An external recording unit (not shown) for recording image information and the like may be connected to the processor device 16 .

As shown in FIG. 2, the light source device 14 includes V-LED (Violet Light Emitting Diode) 20a, B-LED (Blue Light Emitting Diode) 20b, G-LED (Green Light Emitting Diode) 20c, R-LED (Red Light Emitting Diode) 20d, a light source control section 21 for controlling the driving of these four color LEDs 20a to 20d, and an optical path coupling section 23 for coupling the optical paths of the four color lights emitted from the four color LEDs 20a to 20d. . The light coupled by the optical path coupling section 23 is irradiated into the subject through the light guide 41 and the illumination lens 45 inserted into the insertion section 12a. Note that an LD (Laser Diode) may be used instead of the LED.

As shown in FIG. 3, the V-LED 20a emits violet light V with a central wavelength of 405±10 nm and a wavelength range of 380-420 nm. The B-LED 20b generates blue light B with a central wavelength of 460±10 nm and a wavelength range of 420-500 nm. The G-LED 20c generates green light G with a wavelength range of 480-600 nm. The R-LED 20d emits red light R with a central wavelength of 620-630 nm and a wavelength range of 600-650 nm.

The light source control unit 21 controls the V-LED 20a, B-LED 20b, G-LED 20c, and R-LED 20d in any of the normal observation mode, first special observation mode, second special observation mode, and simultaneous observation mode. light up. Therefore, the observation object is irradiated with light in which four colors of light, ie, violet light V, blue light B, green light G, and red light R, are mixed. In the normal observation mode, the light source control unit 21 controls the LEDs 20a to 20d so that the light amount ratio among the violet light V, blue light B, green light G, and red light R is Vc:Bc:Gc:Rc. Control. On the other hand, in the first special observation mode, the second special observation mode, and the simultaneous observation mode, the light source control unit 21 sets the light amount ratio among the violet light V, blue light B, green light G, and red light R to Vs:Bs: Each of the LEDs 20a to 20d is controlled so that Gs:Rs.

As shown in FIG. 2, the light guide 41 is built in the endoscope 12 and the universal cord (the cord connecting the endoscope 12 and the light source device 14 and the processor device 16). The coupled light is propagated to the distal end 12d of the endoscope 12. FIG. A multimode fiber can be used as the light guide 41 . As an example, it is possible to use a thin fiber cable with a core diameter of 105 μm, a clad diameter of 125 μm, and a diameter of φ0.3 to 0.5 mm including a protective layer serving as an outer sheath.

A distal end portion 12d of the endoscope 12 is provided with an illumination optical system 30a and an imaging optical system 30b. The illumination optical system 30 a has an illumination lens 45 through which the light from the light guide 41 is applied to the observation object. The imaging optical system 30 b has an objective lens 46 and an imaging sensor 48 . Reflected light from an observation target enters an imaging sensor 48 via an objective lens 46 . As a result, a reflected image of the observation target is formed on the imaging sensor 48 .

The imaging sensor 48 is a color imaging sensor that captures a reflected image of the subject and outputs an image signal. The imaging sensor 48 is preferably a CCD (Charge Coupled Device) imaging sensor, a CMOS (Complementary Metal-Oxide Semiconductor) imaging sensor, or the like. The imaging sensor 48 used in the present invention is a color imaging sensor for obtaining three-color RGB image signals of R (red), G (green), and B (blue), that is, R pixels provided with R filters. , G pixels provided with G filters, and B pixels provided with B filters.

The imaging sensor 48 is a so-called complementary color imaging sensor provided with C (cyan), M (magenta), Y (yellow) and G (green) complementary color filters instead of the RGB color imaging sensor. can be When a complementary color imaging sensor is used, CMYG four-color image signals are output, so it is necessary to convert the CMYG four-color image signals into RGB three-color image signals by complementary color-primary color conversion. . Also, the imaging sensor 48 may be a monochrome imaging sensor that does not have a color filter. In this case, the light source control unit 21 needs to turn on the blue light B, the green light G, and the red light R in a time-division manner, and to add synchronization processing to the imaging signal processing.

An image signal output from the imaging sensor 48 is transmitted to the CDS/AGC circuit 50 . The CDS/AGC circuit 50 performs correlated double sampling (CDS) and automatic gain control (AGC) on the analog image signal. The image signal that has passed through the CDS/AGC circuit 50 is converted into a digital image signal by an A/D converter (A/D (Analog/Digital) converter) 52 . The A/D converted digital image signal is input to the processor device 16 .

The processor device 16 includes a receiving section 53, a DSP (Digital Signal Processor) 56, a noise removing section 58, an image processing switching section 60, a normal image processing section 62, a special image processing section 64, and a video signal generating section. 66. The receiver 53 receives digital RGB image signals from the endoscope 12 . The R image signal corresponds to the signal output from the R pixel of the image sensor 48, the G image signal corresponds to the signal output from the G pixel of the image sensor 48, and the B image signal is output from the B pixel of the image sensor 48. It corresponds to the signal that is

The DSP 56 performs various signal processing such as defect correction processing, offset processing, gain correction processing, linear matrix processing, gamma conversion processing, and demosaicing processing on the received image signal. In the defect correction process, signals of defective pixels of the imaging sensor 48 are corrected. In the offset processing, dark current components are removed from the RGB image signals subjected to the defect correction processing, and an accurate zero level is set. In the gain correction process, the signal level is adjusted by multiplying the RGB image signal after the offset process by a specific gain. The RGB image signals after gain correction processing are subjected to linear matrix processing for enhancing color reproducibility. After that, the brightness and saturation are adjusted by gamma conversion processing. The RGB image signals after the linear matrix processing are subjected to demosaic processing (also called isotropic processing or synchronization processing), and signals of missing colors in each pixel are generated by interpolation. This demosaicing process causes all pixels to have RGB signals.

The noise removal unit 58 removes noise from the RGB image signal by applying noise removal processing (for example, moving average method, median filter method, etc.) to the RGB image signal that has undergone gamma correction or the like in the DSP 56 . The noise-removed RGB image signal is transmitted to the image processing switching section 60 . The "image signal input processing unit" of the present invention corresponds to a configuration including the receiving unit 53, the DSP 56, and the noise removing unit 58.

The image processing switching unit 60 transmits RGB image signals to the normal image processing unit 62 when the normal observation mode is set by the mode switching SW 13a, and switches between the first special observation mode, the second special observation mode, and the simultaneous observation mode. When the observation mode is set, the RGB image signal is sent to the special image processing section 64 .

The normal image processing unit 62 performs color conversion processing, color enhancement processing, and structure enhancement processing on the RGB image signal. In the color conversion processing, the digital RGB image signal is subjected to 3×3 matrix processing, gradation conversion processing, three-dimensional LUT processing, etc., and converted into a color-converted RGB image signal. Next, various color enhancement processes are applied to the RGB image signals that have undergone the color conversion process. Structural enhancement processing such as spatial frequency enhancement is performed on the color-enhanced RGB image signals. The RGB image signal subjected to structure enhancement processing is input from the normal image processing unit 62 to the video signal generation unit 66 as the RGB image signal of the normal image.

The special image processing section 64 operates when the first special observation mode, the second special observation mode, or the simultaneous observation mode is set. The special image processing unit 64 includes a first special image processing unit 64a that generates a first special image, a second special image processing unit 64b that generates a second special image, and a first special image and a second special image. and a simultaneous display image processing unit 64c for generating a simultaneous display special image for simultaneous display. However, the first special image processing section 64a does not generate the second special image. Also, the second special image processing unit 64b does not generate the first special image. Details of the first special image processing unit 64a, the second special image processing unit 64b, and the simultaneous display image processing unit 64c will be described later. The RGB image signals of the first special image, the second special image, and the special image for simultaneous display generated by the special image processing section 64 are input to the video signal generation section 66 .

The video signal generation unit 66 converts the RGB image signal input from the normal image processing unit 62 or the special image processing unit 64 into a video signal for display as an image that can be displayed on the monitor 18 . Based on this video signal, the monitor 18 displays the normal image, the first special image, or the second special image, respectively, or simultaneously displays the first special image and the second special image.

As shown in FIG. 4, the first special image processing unit 64a includes an inverse gamma conversion unit 70, a log conversion unit 71, a signal ratio calculation unit 72, a first color information conversion unit 73 for signal ratio space, An RGB conversion section 77 , a structure enhancement section 78 , an inverse Log conversion section 79 and a gamma conversion section 80 are provided. Further, the first special image processing section 64 a includes a brightness adjustment section 81 between the RGB conversion section 77 and the structure enhancement section 78 .

The inverse gamma conversion unit 70 performs inverse gamma conversion on the input RGB image signals. Since the RGB image signal after the inverse gamma conversion is a reflectance linear RGB signal that is linear with respect to the reflectance from the specimen, signals related to various biological information of the specimen account for a large proportion of the RGB image signal. Become. The reflectance linear R image signal is the first R image signal, the reflectance linear G image signal is the first G image signal, and the reflectance B linear image signal is the first B image signal.

The Log converter 71 Log-converts each of the first RGB image signals (corresponding to the "first color image signal" of the present invention). As a result, a Log-transformed R image signal (logR), a Log-transformed G image signal (logG), and a Log-transformed B image signal (logB) are obtained. The signal ratio calculator 72 (corresponding to the “color information acquisition unit” of the present invention) performs difference processing (logG-logB =logG/B=-log(B /G)) to calculate the first B/G ratio (corresponding to the "first signal ratio Mx" of the present invention). Here, the "first B/G ratio" represents -log(B/G) with "-log" omitted. Further, the first G/R ratio (the "second 1 signal ratio Nx”) is calculated. As with the first B/G ratio, the first G/R ratio represents -log(G/R) with "-log" omitted. Hereinafter, the two-dimensional color space formed by the first B/G ratio and the first G/R ratio will be referred to as "first signal ratio space (corresponding to the "first feature space" of the present invention)".

Note that the first B/G ratio and the first G/R ratio are obtained from pixel values of pixels at the same position in the B image signal, G image signal, and R image signal. Also, the first B/G ratio and the first G/R ratio are obtained for each pixel. In addition, since the first B/G ratio is correlated with the blood vessel depth (the distance from the surface of the mucous membrane to the position where the specific blood vessel is located), when the blood vessel depth differs, the first B/G ratio also varies accordingly. do. Further, since the first G/R ratio is correlated with the blood volume (hemoglobin index), when the blood volume fluctuates, the first G/R ratio also fluctuates accordingly.

The first color information conversion section 73 for the signal ratio space performs the first color information conversion processing for the signal ratio space on the first B/G ratio and the first G/R ratio obtained by the signal ratio calculation section 72. are converted into the second B/G ratio and the second G/R ratio. The second B/G ratio corresponds to the "second signal ratio My" of the invention, and the second G/R ratio corresponds to the "second signal ratio Ny" of the invention. The first color information conversion unit 73 for signal ratio space is composed of a two-dimensional LUT (Look Up Table), and converts a first B/G ratio, a first G/R ratio, and the first B/G ratio, first G/R ratio A second B/G ratio and a second G/R ratio obtained by performing the first color information conversion process for the signal ratio space based on the ratio are stored in association with each other. The details of the first color information conversion process for signal ratio space will be described later.

As shown in FIG. 5A, in the first signal ratio space formed by the first B/G ratio on the vertical axis and the first G/R ratio on the horizontal axis, a first range in which normal mucosa is distributed, The second range, in which the atrophic mucosa that has atrophied due to atrophic gastritis is distributed, and the third range, in which the deep blood vessels that exist under the atrophic mucosa that has atrophied due to atrophic gastritis and are seen through with atrophy are distributed in the first quadrant. ing. In this first signal ratio space, there is a difference D12x between the first range and the second range (e.g., the average value of the first range and the average value of the second range), and the difference between the first range and the third range is There is a difference D13x (eg, the mean value of the first range and the mean value of the third range) between. The difference D12x appears as a difference in saturation between the colors in the first range and the second range on the image, and the difference D13x appears as a difference in hue between the colors in the first range and the third range on the image.

In FIG. 5A, "first" indicates "first range", "second" indicates "second range", and "third" indicates "third range". The notation of "first" to "third" is the same in the following figures. In FIG. 5A, the "first" of the "first B/G ratio" on the vertical axis is omitted, and the "first" of the "first G/R ratio" on the horizontal axis is omitted. ing. Similar abbreviations are also used in the following figures.

On the other hand, the second signal ratio space formed by the second B/G ratio and the second G/R ratio obtained by the first color information conversion processing for the signal ratio space (the vertical axis is the second B/G ratio, the horizontal axis is 5B, the first range, the second range, and the third range are distributed in the same manner as in the first signal ratio space. In the second signal ratio space (corresponding to the "second feature space" of the present invention), there is a difference D12y between the first range and the second range (for example, the mean of the first range and the mean of the second range value), and there is a difference D13y between the first range and the third range (eg, the average value of the first range and the average value of the third range).

The difference D12y appears as a difference in saturation and hue between the colors in the first range and the second range on the image, and the difference D12y is larger than the difference D12x. Also, the difference D13y, like the difference D13x, appears as a difference in hue between the colors in the first range and the third range on the image, and the difference D13y is larger than the difference D13x. Furthermore, the coordinates of the first range on the second signal ratio space are different from the coordinates of the first range on the first signal ratio space. That is, at least one of the saturation and hue in the first range is different before and after the first color information conversion process for the signal ratio space.

As described above, the difference between the first range and the second range and the difference between the first range and the third range are increased by the first color information conversion processing for the signal ratio space, and At least one of the saturation and hue in the first range is different before and after conversion in the color information conversion process. As a result, on the first special image obtained based on the second B/G ratio and the second G/R ratio after the first color information conversion processing for the signal ratio space, the atrophic mucous membrane and the atrophic submucosal membrane are transparent due to atrophy. The boundary between the atrophic part with deep blood vessels and the like and the normal part with normal mucous membrane is clearly displayed.

Note that first elements a ^* _x and b ^* _x (in CIE Lab space) obtained by Lab-converting the first RGB image signals in a Lab conversion unit (not shown (corresponding to the “color information acquisition unit” of the present invention)) The first color information conversion process for the ^{ab space} , which is the same as the first color information conversion process for the signal ratio space, is applied to , effects similar to those described above can be obtained.

Here, FIG. 6A shows the distribution of the first to third ranges on the 1ab space formed by the first elements a ^* _x and b ^* _x, and the difference D12x between the first range and the second range. , and the difference D13x between the first range and the third range. On the other hand, FIG. 6B shows the distribution of the first to third ranges in the second ab space formed by the second elements a ^* _y and b ^* _y obtained by the first color information conversion process for the ab space. A difference D12y between the first range and the second range and a difference D13y between the first range and the third range are shown. As shown in FIG. 6, the first color information conversion process for the ab space can increase the difference between the first range and the second range and the difference between the first range and the third range. The 1ab space corresponds to the "first feature space" of the invention, and the 2ab space corresponds to the "second feature space" of the invention.

In the RGB conversion section 77 (corresponding to the "color image signal conversion section" of the present invention), at least one of the first RGB image signals is used to convert the first color information conversion section 73 for the signal ratio space. The second B/G ratio and the second G/R ratio that have passed through are converted into second RGB image signals (corresponding to the "second color image signal" of the present invention). For example, the RGB converter 77 converts the second B/G ratio into the second B image signal by performing calculation based on the G image signal and the second B/G ratio among the first RGB image signals. Further, the RGB conversion section 77 converts the second G/R ratio into a second R image signal by performing a calculation based on the G image signal of the first RGB image signal and the second G/R ratio. Further, the RGB conversion unit 77 outputs the first G image signal as the second G image signal without performing special conversion.

The brightness adjustment unit 81 adjusts the pixel values of the second RGB image signal using the first RGB image signal and the second RGB image signal. The reason why the brightness adjustment unit 81 adjusts the pixel values of the second RGB image signals is as follows. Since the second RGB image signals are subjected to the first color information conversion processing for the signal ratio space by the first color information conversion unit 73 for the signal ratio space, there is a possibility that the brightness of the second RGB image signals will be significantly different from that of the first RGB image signals. There is Therefore, the pixel values of the second RGB image signals are adjusted by the brightness adjustment unit 81 so that the second RGB image signals after brightness adjustment have the same brightness as the first RGB image signals.

The brightness adjustment unit 81 includes a first brightness information calculation unit 81a for obtaining first brightness information Yin based on the first RGB image signals, and a second brightness information calculation unit 81a for obtaining second brightness information Yout based on the second RGB image signals. and an information calculation unit 81b. The first brightness information calculator 81a calculates the first brightness information Yin according to the arithmetic expression "kr×pixel value of first R image signal+kg×pixel value of first G image signal+kb×pixel value of first B image signal". Calculate Similarly to the first brightness information calculation section 81a, the second brightness information calculation section 81b also calculates the second brightness information Yout according to the same arithmetic expression as above. After obtaining the first brightness information Yin and the second brightness information Yout, the brightness adjustment unit 81 calculates the pixel values of the second RGB image signals by performing calculations based on the following equations (E1) to (E3). adjust.
(E1): R ^* =pixel value of second R image signal×Yin/Yout
(E2): G ^* =pixel value of second G image signal×Yin/Yout
(E3): B ^* =pixel value of second B image signal×Yin/Yout
Here, "R ^* " represents the second R image signal after brightness adjustment, "G ^* " represents the second G image signal after brightness adjustment, and "B ^* " represents the second B image signal after brightness adjustment. ing. Also, "kr", "kg", and "kb" are arbitrary constants in the range of "0" to "1".

The structure enhancement section 78 applies structure enhancement processing to the second RGB image signals after brightness adjustment by the brightness adjustment section 81 . Frequency filtering or the like is used as the structure enhancement processing. The inverse Log transformation unit 79 performs inverse Log transformation on the second RGB image signals that have passed through the structure enhancement unit 78 . As a result, second RGB image signals having antilogarithmic pixel values are obtained. The gamma conversion section 80 performs gamma conversion on the second RGB image signals that have passed through the inverse Log conversion section 79 . Thereby, a second RGB image signal having a gradation suitable for an output device such as the monitor 18 is obtained. The RGB image signal that has passed through the gamma conversion section 80 is sent to the simultaneous display image processing section 64c or the video signal generation section 66 as the RGB image signal of the first special image.

The first color information transform processing for the signal ratio space is composed of polar coordinate transform processing, first processing and second processing for the signal ratio space, and orthogonal coordinate transform processing. First, the first B/G ratio and the first G/R ratio obtained by the signal ratio calculator 72 are converted into a radius vector r and an angle θ by performing polar coordinate conversion processing. Next, the first processing for the signal ratio space is performed. As shown in FIG. 7, in the first signal ratio space, the radius r of coordinates P1 within the radius change range R1 is changed, and the radius of coordinates outside the radius change range R1 is not changed. In the radius change range R1, the radius r is within the range from "rA" to "rB" and the angle θ is within the range from "θA" to "θB" (rA<rB, θA<θB). . This radius change range R1 is a region including the second range in which the atrophic mucosa atrophied due to atrophic gastritis is distributed, and the first range in which the normal mucosa is distributed and the submucosa atrophied due to atrophic gastritis. , and the third range in which deep-layer blood vessels that see through with atrophy are distributed.

In addition, in the first processing for the signal ratio space, the angle θ of the coordinates of the radius vector change range R1 is not changed. Further, in the first processing for the signal ratio space, when the radius r is in the range from "rp" to "rB", the radius r is changed at a radius change rate Vx larger than "1". Expanding processing is performed to change the radius r, and compression processing is performed to change the radius r at a radius variation rate Vy that is smaller than "1" within the range of the radius r from "rA" to "rp". preferably. Note that when the radius vector change rate is "1", the size of the radius vector r does not change even if the processing for changing the radius vector r is performed.

By performing the above-described first processing for the signal ratio space, as shown in FIG. 8, the radius vector r within the radius vector change range R1 is changed to a radius vector Er smaller than the radius vector r. Further, the rate of change of the radius vector is represented by the slope of the "straight line L1" indicating the tangent line of the line CV1 that relates the radius vector r and the radius vector Er. While the slope is larger than "1", the slope of the straight line L1 is smaller than "1" between "rA" and "rp". On the other hand, the radius r outside the radius change range R1 is converted into a radius Er having the same size as the radius r (identical transformation). Further, the slope of the straight line L1 is "1" outside the radius vector change range R1.

As shown in FIG. 9A, before the first processing for the signal ratio space, the first range, the second range, and the third range are close to each other, but the first processing for the signal ratio space After that, as shown in FIG. 9B, while the coordinates of the first range and the third range are maintained as they are, the coordinates of the second range are moved to the reference range including the origin. The reference range is a low saturation range that does not include the first range and the third range after the first processing for the signal ratio space.

Note that even when the plurality of pieces of first color information are the first elements a ^* _x and b ^* _x, as shown in FIG. While maintaining the position, the coordinates of the second range are moved to the reference range including the origin. Here, FIG. 10A shows the distribution of the first to third ranges before the first processing for the ab space, and FIG. 10B shows the distribution of the first to third ranges after the first processing for the ab space. represents the distribution.

In the second processing for the signal ratio space, as shown in FIG. 11A, the angle θ of the coordinate P2 within the angle change range R2 is changed, while the angle θ of the coordinates outside the angle change range R2 is not changed. No. The angle change range R2 is set to include the first range and the third range. Note that in the second processing for the signal ratio space, the radius vector r of the coordinates of the angle change range R2 is not changed.

In the angle change range R2, a first center line CL1 is set between the first range and the third range. The first center line CL1 is at an angle θc, and in the angle change range R2, in the second processing for the signal ratio space, an angle θ less than the angle θc is rotated clockwise, whereas an angle θ less than the angle θc is rotated clockwise. is rotated in the counterclockwise direction. An angle θ in a certain range R2x from the first center line CL1 is expanded by an angle change rate Wx whose angle change rate is greater than 1, and an angle θ in a range R2y exceeding the range R2x is Preferably, the compression process is changed at an angle change rate Wy whose angle change rate is smaller than "1". In addition, by the second processing for the signal ratio space, the coordinates of the angle change range R2 are set to the range of ±90 degrees from the first center line CL1 (in the signal ratio space, the “positive” horizontal axis is 0 ° and the angle is When expressed from 0° to 360°, it is preferable to move within a range P (see FIG. 11B) from “270°+θc” to “θc+90°”. Note that when the angle change rate is "1", even if the processing for changing the angle θ is performed, the magnitude of the angle θ does not change.

By performing the above second processing for the signal ratio space, as shown in FIG. 12, within the angle change range R2, the angle θ less than or equal to the angle θc is changed to an angle Eθ that is smaller than the angle θ. On the other hand, the angle θ greater than or equal to the angle θc is changed to an angle Eθ that is larger than the angle θ. Further, the angle change rate is represented by the slope of the "straight line L2" indicating the tangent to the line CV2 that relates the angle θ and the angle Eθ. On the other hand, the slope of the straight line L2 is smaller than "1" within the range R2y. On the other hand, the angle θ outside the angle change range R2 is converted into an angle Eθ having the same magnitude as the angle θ (identity conversion). The slope of the straight line L2 is "1" outside the angle change range R2.

As shown in FIG. 13A (A), before the second processing for the signal ratio space, the first range and the third range are separated from the second range, but the first range and the third range approaching each other. After the second processing for the signal ratio space, as shown in FIG. 13A(B), most of the coordinates in the first range are in the second range in the signal ratio space while the coordinates in the second range are maintained in the reference range. While moving to the quadrant, most of the coordinates in the third range move to the fourth quadrant of the signal ratio space. When the second processing for the signal ratio space is completed, the second processed radius vector r and angle θ for the signal ratio space are subjected to orthogonal coordinate transformation processing. Thereby, a second B/G ratio and a second G/R ratio are obtained.

Note that even when the plurality of pieces of first color information are the first elements a ^* _x and b ^* _x, the coordinates of the second range are maintained within the reference range by the second processing for the ab space, as shown in FIG. In this state, most of the coordinates in the first range move to the second quadrant of the secondab space, while most of the coordinates in the third range move to the fourth quadrant of the secondab space. Here, FIG. 13B(A) shows the distribution of the first to third ranges before the second processing for the ab space, and FIG. 13B(B) shows the distribution of the first to third ranges after the second processing for the ab space. represents the distribution. Further, it is preferable that the brightness adjustment section 81 adjusts pixel values for the second RGB image signals obtained after the first processing and the second processing for the ab space. The pixel value adjustment method for the second RGB image signals is the same as described above.

The second special image processing section 64b has substantially the same configuration as the first special image processing section 64a, but instead of the first color information conversion section 73 for the signal ratio space, the second color information conversion section 73 for the signal ratio space It has an information converter (not shown). The second color information conversion section for signal ratio space performs second color information conversion processing for signal ratio space on the first B/G ratio and the first G/R ratio obtained by the signal ratio calculation section 72. , a second B/G ratio, and a second G/R ratio (corresponding to the “plurality of second color information” of the present invention). The second color information conversion unit for the signal ratio space is composed of a two-dimensional LUT (Look Up Table), and includes a first B/G ratio, a first G/R ratio, and the first B/G ratio and first G/R ratio. A second B/G ratio and a second G/R ratio obtained by performing the second color information conversion process for the signal ratio space based on are associated with each other and stored. The details of the second color information conversion process for signal ratio space will be described later.

As shown in FIG. 14A, in the first signal ratio space formed by the first B/G ratio on the vertical axis and the first G/R ratio on the horizontal axis, the first range, the second range, and the first 3 ranges are distributed, and there is a difference D12x between the first range and the second range (for example, the average value of the first range and the average value of the second range), and the first range and the third range There is a difference D13x (for example, the average value of the first range and the average value of the third range) between the ranges (similar to FIG. 5A).

On the other hand, the second signal ratio space formed by the second B/G ratio and the second G/R ratio obtained by the second color information conversion processing for the signal ratio space (the vertical axis is the second B/G ratio, the horizontal axis is the second 2G/R ratio), as shown in FIG. 14B, the first range, the second range, and the third range are distributed in the same manner as in the first signal ratio space. In the second signal ratio space, there is a difference D12y between the first range and the second range (e.g., the average value of the first range and the average value of the second range), and the difference between the first range and the third range In between there is a difference D13y (eg the mean value of the first range and the mean value of the third range).

Like the difference D12x, the difference D12y appears as a difference in saturation between the colors in the first range and the second range on the image, and the difference D12y is larger than the difference D12x. Also, the difference D13y, like the difference D13x, appears as a difference in hue between the colors in the first range and the third range on the image, and the difference D13y is larger than the difference D13x. Furthermore, the coordinates of the first range on the second signal ratio space are the same as the coordinates of the first range on the first signal ratio space. That is, the saturation and hue in the first range are the same before and after the second color information conversion process for the signal ratio space.

As described above, the difference between the first range and the second range and the difference between the first range and the third range are increased by the first color information conversion process for the signal ratio space, and are increased by the second color information conversion process for the signal ratio space. The saturation and hue of the first range are the same before and after conversion in the color information conversion process. As a result, the second special image obtained from the second B/G ratio and the second G/R ratio after the second color information conversion processing for the signal ratio space is displayed while maintaining the color of the normal portion. Atrophic mucous membranes among the atrophic regions with atrophic gastritis are displayed in a faded tone. Further, on the second special image, the color of the deep-layer blood vessels that are becoming visible due to atrophy under the atrophic mucous membrane can be clearly displayed by changing from red to magenta or the like. Therefore, since the second special image is displayed in the original color when atrophic gastritis occurs, the difference in color between the normal part and the atrophic part is clear.

When the plurality of first color information are the first elements a ^* _x and b ^* _x, the above second color information for the signal ratio space for the first elements a ^* _x and b ^* _x By performing the second color information conversion process for the ab space, which is the same as the conversion process, the same effects as described above can be obtained.

Here, FIG. 15A shows the distribution of the first to third ranges on the 1ab space formed by the first elements a ^* _x and b ^* _x, and the difference D12x between the first range and the second range. , and the difference D13x between the first range and the third range. On the other hand, FIG. 15B shows the distribution of the first to third ranges in the second ab space formed by the second elements a ^* _y and b ^* _y obtained by the second color information conversion process for the ab space. A difference D12y between the first range and the second range and a difference D13y between the first range and the third range are shown. As shown in FIG. 15, the difference between the first range and the second range and the difference between the first range and the third range are obtained by the second color information conversion processing for the ab space while maintaining the coordinates of the first range. can increase the difference between

The second color information transform processing for the signal ratio space is composed of polar coordinate transform processing, first processing and third processing for the signal ratio space, and orthogonal coordinate transform processing. Since the polar coordinate transformation processing, the first processing for the signal ratio space, and the rectangular coordinate transformation processing are the same as those described above, the description thereof is omitted.

In the third processing for the signal ratio space, based on the radius vector r and the angle θ after the first processing for the signal ratio space, the angle θ is changed to maintain the coordinates of the first range, and the third range A third process for the signal ratio space is performed to shift the coordinates of . In the third processing for the signal ratio space, as shown in FIG. 16A, the angle θ of the coordinate P3 within the angle change range R3 is changed, while the angle θ of the coordinates outside the angle change range R3 is not changed. No. The angle change range R3 is set so as to include the third range and not include the first range. Note that in the third processing for the signal ratio space, the radius vector r of the coordinates of the angle change range R3 is not changed.

In the angle change range R3, a second centerline CL2 is set between the first range and the third range. The second center line CL2 is at an angle θd, and the angle θ less than or equal to the angle θd within the angle change range R3 is rotated clockwise. An angle θ in a certain range R3x from the second center line CL2 is expanded by an angle change rate Wx whose angle change rate is greater than 1, and an angle θ in a range R3y exceeding the range R3x is expanded. Preferably, the compression process is changed at an angle change rate Wy whose angle change rate is smaller than "1". Further, by the third processing for the signal ratio space, the coordinates of the angle change range R3 are set to the range of −90 degrees from the second center line CL2 (in the signal ratio space, the “positive” horizontal axis is 0 degrees, and the angle is When expressed from 0° to 360°, it is preferable to move within a range Q (see FIG. 16B) from “270°+θd” to “θd”. Note that when the angle change rate is "1", even if the processing for changing the angle θ is performed, the magnitude of the angle θ does not change.

By performing the third process for the signal ratio space described above, the angle θ is changed to an angle Eθ that is smaller than the angle θ within the angle change range R3, as shown in FIG. Further, the angle change rate is represented by the slope of the "straight line L3" indicating the tangent to the line CV3 that relates the angle θ and the angle Eθ. On the other hand, the slope of the straight line L3 is smaller than "1" within the range R3y. On the other hand, the angle θ outside the angle change range R3 is converted into an angle Eθ having the same magnitude as the angle θ (identity conversion). The slope of the straight line L3 is "1" outside the angle change range R3.

As shown in FIG. 18A (A), before the third processing for the signal ratio space, the first range and the third range are separated from the second range, but the first range and the third range are separated from each other. It is approaching. After the third processing for the signal ratio space, as shown in FIG. 18A (B), while maintaining the coordinates of the second range in the reference range, the Most of the three-range coordinates move into the fourth quadrant of the signal ratio space. Moving the coordinates of the third range from the first quadrant to the fourth quadrant corresponds to changing the hue while maintaining the saturation on the second special image. This causes the coordinates of the first range, the second range, and the third range to be completely separated.

Note that even when the plurality of pieces of first color information are the first elements a ^* _x and b ^* _x, as shown in FIG. While maintaining the coordinates of the first range, most of the coordinates of the third range are moved to the fourth quadrant of the 2ab space, while keeping the coordinates of the first range unchanged. Here, FIG. 18B(A) shows the distribution of the first to third ranges before the third processing for the ab space, and FIG. 18B(B) shows the distribution of the first to third ranges after the third processing for the ab space. represents the distribution. Further, it is preferable that the brightness adjustment unit 81 adjusts the pixel values of the second RGB image signals obtained after the first processing and the third processing for the ab space. The pixel value adjustment method for the second RGB image signals is the same as described above.

The simultaneous display image processing unit 64c generates a simultaneous display special image based on the first special image and the second special image generated by the first special image processing unit 64a and the second special image processing unit 64b. As shown in FIG. 19, the monitor 18 displays the first special image on one side and the second special image on the other side based on the special image for simultaneous display. In the first special image, the boundary between the normal part and the atrophic part is very clear, so it is an image that makes it easy to grasp the position of the atrophic part, but the normal part is not the original color of the stomach mucosa. Since it is displayed in pseudo-color, it is an image that the doctor feels uncomfortable with. On the other hand, in the second special image, compared with the first special image, the boundary between the normal part and the atrophied part is clear to some extent, and the color of the normal part is displayed in the original color of the stomach. It is an image without a sense of incongruity. By simultaneously displaying the first special image and the second special image, it is possible to detect the boundary between the normal part and the atrophic part while grasping the color of the normal part.

Next, a series of flows of the present invention will be described along the flowchart of FIG. First, the normal observation mode is set, and the insertion portion 12a of the endoscope 12 is inserted into the specimen. When the distal end portion 12d of the insertion portion 12a reaches the stomach, the mode switching SW 13a is operated to switch from the normal observation mode to the first and second special observation modes. When diagnosing atrophic gastritis while observing both the first special image and the second special image, the mode is switched to the simultaneous observation mode.

The signal ratio calculator 72 calculates the first B/G ratio and the first G/R ratio based on the RGB image signals obtained after switching to the first and second special observation modes. Next, when the first special observation mode is set, the first color information conversion section 73 for the signal ratio space converts the first B/G ratio and the first G/R ratio into the first B/G ratio for the signal ratio space. 1-color information conversion processing converts to a second B/G ratio and a second G/R ratio. A first special image is generated based on the second B/G ratio and the second G/R ratio after the first color information conversion processing for the signal ratio space. The first special image is displayed on monitor 18 .

On the other hand, when the second special observation mode is set, the second color information conversion section for signal ratio space converts the first B/G ratio and first G/R ratio to the second color for signal ratio space. By information conversion processing, the ratio is converted to the second B/G ratio and the second G/R ratio. A second special image is generated based on the second B/G ratio and the second G/R ratio after the second information conversion processing for the signal ratio space. The second special image is displayed on monitor 18 .

Note that the simultaneous observation mode is not limited to simultaneous display of the first special image and the second special image, and may be simultaneous display of the first special image and the normal image, for example. Alternatively, the second special image and the normal image may be displayed simultaneously. In this case, the normal image processing section 62 and the special image processing section 64 each generate display images, which are displayed on the monitor 18 via the video signal generation section 66 .

Also, in the simultaneous observation mode, the first special image and the third special image which is not subjected to either the first color information conversion process or the second color information conversion process for the signal ratio space are simultaneously displayed. good too. This third special image is generated by a third special image processing section (not shown) provided in the special image processing section 64 . In this case, the third special image processing section differs from the first and second special image processing sections 64a and 64b in that the signal ratio space necessary for the first color information conversion processing and the second color information conversion processing for the signal ratio space is used. It does not have a first color information conversion section and a second color information conversion section for. Other than that, it is the same as the first and second special image processing units 64a and 64b. When generating the third special image, it is preferable to make the light intensity of the violet light V higher than the light intensity of the blue light B, the green light G, and the red light R, and emit light of each color. The third special image obtained under such lighting conditions is an image in which superficial blood vessels are emphasized and displayed while the entire image remains bright.

In the above embodiment, the signal ratio calculator 72 obtains the first B/G ratio and the first G/R ratio from the first RGB image signals, and these first B/G ratio and first G/R ratio are used for the signal ratio space. Although converted into the second B/G ratio and the second G/R ratio in the first and second color information conversion processes, the first RGB image signal is converted to a plurality of first B/G ratios and a plurality of first G/R ratios different from the first B/G ratio and the first G/R ratio. Color information may be obtained and the plurality of first color information may be converted into a plurality of second color information by first and second color information conversion processes for a particular feature space.

For example, color difference signals Cr and Cb may be obtained as a plurality of pieces of color information, and the first and second color information conversion processes for the CrCb space may be applied to the color difference signals Cr and Cb. The first color information conversion process for the CrCb space is performed by the first special image processing section 94a shown in FIG. Unlike the first special image processing section 64a, the first special image processing section 94a includes an inverse gamma conversion section 70, a log conversion section 71, a signal ratio calculation section 72, a first color information conversion section 73 for signal ratio space, an inverse The Log conversion section 79 and the gamma conversion section 80 are not provided. Instead, the first special image processing section 94a includes a luminance/color difference signal conversion section 85 and a first color information conversion section 86 for CrCb space. Other configurations of the first special image processing section 94a are the same as those of the first special image processing section 64a.

A luminance/color-difference signal conversion unit 85 (corresponding to the “color information acquisition unit” of the present invention) converts the first RGB image signals into a luminance signal Y and first color-difference signals Cr_x and Cb_x. A well-known conversion formula is used for conversion to the first color difference signals Cr and Cb. The first color difference signals Cr_x and Cb_x are sent to the first color information conversion section 86 for CrCb space. The luminance signal Y is sent to the RGB converter 77 and the brightness adjuster 81 . The RGB conversion unit 77 converts the second color difference signals Cr_y and Cb_y and the luminance signal Y, which have undergone the first color information conversion processing for the CrCb space, into second RGB image signals. The brightness adjustment unit 81 uses the brightness signal Y as the first brightness information Yin, and uses the second brightness information obtained by the second brightness information calculation unit 81b as the second brightness information Yout to obtain the second RGB Adjust the pixel value of the image signal. The method of calculating the second brightness information Yout and the method of adjusting the pixel values of the second RGB image signals are the same as in the case of the first special image processing section 64a.

The first color information conversion unit 86 for CrCb space performs first color information conversion processing for CrCb space on the first color difference signals Cr_x and Cb_x to convert them into second color difference signals Cr_y and Cb_y. The first color information conversion unit 86 for CrCb space is composed of a two-dimensional LUT (Look Up Table), and converts first color difference signals Cr_x, Cb_x and first color information for CrCb space based on the first color difference signals Cr_x, Cb_x. Second color difference signals Cr_y and Cb_y obtained by performing color information conversion processing are stored in association with each other. The details of the first color information conversion process for the CrCb space will be described later.

As shown in FIG. 22A, in the first CrCb space (corresponding to the "first feature space" of the present invention) formed by the first color difference signals Cr_x and Cb_x, the first range and the second range are , and the third range are distributed in the second quadrant. In this first CrCb space, there is a difference D12x between the first range and the second range (e.g., the mean value of the first range and the mean value of the second range), and the difference between the first range and the third range has a difference D13x (eg, the mean value of the first range and the mean value of the third range). The difference D12x appears as a difference in saturation on the image between the colors in the first range and the second range on the image, and the difference D13x is the difference in hue on the image between the colors in the first range and the third range on the image. expressed as

On the other hand, in the second CrCb space formed by the second color difference signals Cr_y and Cb_y obtained by the first color information conversion processing for the CrCb space, as shown in FIG. Each third range is distributed in a separate quadrant. In this second CrCb space (corresponding to the "second feature space" of the present invention), the difference D12y between the first range and the second range (for example, the average value of the first range and the average value of the second range ), and there is a difference D13y between the first range and the third range (eg, the average value of the first range and the average value of the third range).

The difference D12y appears as a difference in saturation and hue between the colors in the first range and the second range on the image. Also, the difference D12y is larger than the difference D12x. On the other hand, the difference D13y appears as a hue difference between the colors in the first range and the third range on the image. Also, the difference D13y is larger than the difference D13x. Furthermore, the coordinates of the first range on the second CrCb space are different from the coordinates of the first range on the first CrCb space. That is, at least one of the saturation and hue in the first range is different before and after the first color information conversion process for the CrCb space.

As described above, the difference between the first range and the second range and the difference between the first range and the third range are increased by the first color information conversion process for the CrCb space. The ranges may differ in saturation and/or hue. Therefore, the first special image similar to that described above can be obtained from the second color difference signals Cr_y and Cb_y that have undergone the first color information conversion processing for the CrCb space.

The second color information conversion processing for the CrCb space is performed by a second special image processing section (not shown) having substantially the same configuration as the first special image processing section 94a. This second special image processing section has a second color information conversion section for the CrCb space instead of the first color information conversion section 86 for the CrCb space. It is the same.

The second color information conversion section for CrCb space performs second color information conversion processing for CrCb space on the first color difference signals Cr_x and Cb_x to convert the first color difference signals Cr_x and Cb_x into second color difference signals Cr_y and Cb_y. The second color information conversion unit for CrCb space is composed of a two-dimensional LUT (Look Up Table), and converts first color difference signals Cr_x, Cb_x and second colors for CrCb space based on the first color difference signals Cr_x, Cb_x. Second color difference signals Cr_y and Cb_y obtained by performing information conversion processing are stored in association with each other. The details of the second color information conversion process for the CrCb space will be described later.

As shown in FIG. 23A, in the first CrCb space formed by the first color difference signals Cr_x and Cb_x, similarly to FIG. is distributed in the second quadrant, and has a difference D12x (difference in saturation) and a difference D13x (difference in hue) between the first range and the second and third ranges. On the other hand, in the second CrCb space formed by the second color difference signals Cr_y and Cb_y obtained by the second color information conversion processing for the CrCb space, as shown in FIG. 23B, the first range and the second range are They are distributed in the same second quadrant, but only the third range is distributed in the first quadrant. In this second CrCb space, there is a difference D12y between the first range and the second range, and a difference D13y between the first range and the third range.

The difference D12y appears as a difference in saturation between the colors in the first range and the second range on the image. Also, the difference D12y is larger than the difference D12x. On the other hand, the difference D13y appears as a hue difference between the colors in the first range and the third range on the image. Also, the difference D13y is larger than the difference D13x. Furthermore, the coordinates of the first range on the second CrCb space are the same as the coordinates of the first range on the first CrCb space. That is, the saturation and hue in the first range are the same before and after the second color information conversion process for the CrCb space.

As described above, the difference between the first range and the second range and the difference between the first range and the third range are increased by the second color information conversion process for the CrCb space. The saturation and hue of the range can be the same. Therefore, a second special image similar to that described above can be obtained from the second color difference signals Cr_y and Cb_y that have undergone the second color information conversion processing for the CrCb space.

The first color information conversion processing for the CrCb space consists of polar coordinate conversion processing, first processing and second processing for the CrCb space, and orthogonal coordinate conversion processing. First, the first color-difference signals Cr_x and Cb_x are subjected to polar coordinate conversion processing to convert them into a radius vector r and an angle θ. Next, in the first processing for the CrCb space, as shown in FIG. 24, the coordinates of the second range are changed in the reference range including the origin on the first CrCb space by changing the radius of the coordinates of the second range. move. The reference range is the range of low saturation that does not include the first range and the third range after the first processing for the CrCb space. On the other hand, in the first processing for CrCb space, the coordinates of the first range and the third range on CrCb space are maintained. Here, the moving method of each range is the same as in the case of the first processing for the signal ratio space.

In the second processing for the CrCb space, as shown in FIG. 25, while maintaining the second range in the reference range, the coordinates of the first range and the third range are separated from each other. 3 Process to move range. The method of moving the first and third ranges is the same as in the second processing for the signal ratio space, and is performed by expanding and compressing the angles. The radius vector r and the angle θ after the second processing for the CrCb space are converted into second color difference signals Cr_y and Cb_y by orthogonal coordinate conversion processing.

The second color information conversion process for CrCb space consists of polar coordinate conversion process, first and third processes for CrCb space, and orthogonal coordinate conversion process. The polar coordinate conversion processing, the first processing for the CrCb space, and the orthogonal coordinate conversion processing are the same as the first color information conversion processing for the CrCb space.

In the third processing for the CrCb space, as shown in FIG. 26, while maintaining the second range in the reference range and maintaining the coordinates of the first range, the first range and the third range are separated. , it is processed to move only the third range. The method of moving this third range is the same as in the case of the third processing for the signal ratio space, and is performed by expanding and compressing the angle.

Hue H (Hue) and saturation S (Saturation) are obtained as color information, and the hue H (Hue) and saturation S (Saturation) are subjected to first and second color information conversion processing for the HS space. may The first color information conversion process for the HS space is performed by the first special image processing section 96a shown in FIG. Unlike the first special image processing section 64a, the first special image processing section 96a includes an inverse gamma conversion section 70, a log conversion section 71, a signal ratio calculation section 72, a first color information conversion section 73 for signal ratio space, an inverse The Log conversion section 79 and the gamma conversion section 80 are not provided. Instead, the first special image processing section 96a includes an HSV conversion section 87 and a first color information conversion section 88 for HS space. Other configurations of the first special image processing section 96a are the same as those of the first special image processing section 64a.

The HSV conversion section 87 (corresponding to the "color information acquisition section" of the present invention) converts the first RGB image signals into a first hue H_x, a first saturation S_x and a brightness V. FIG. Well-known conversion formulas are used for the conversion to the first hue H_x, the first saturation S_x, and the brightness V. FIG. The first hue H_x and the first saturation S_x are sent to the first color information conversion section 88 for the HS space. The brightness V is sent to the RGB converter 77 . The RGB conversion unit 77 converts the second hue H_y, the second saturation S_y, and the brightness V, which have undergone the first color information conversion processing for the HS space, into second RGB image signals. In the brightness adjustment unit 81, the first brightness information obtained by the first brightness information calculation unit 81a as the first brightness information Yin, and the first brightness information obtained by the second brightness information calculation unit 81b as the second brightness information Yout. The pixel values of the second RGB image signals are adjusted using the second brightness information. The method of calculating the first brightness information Yin and the second brightness information Yout and the method of adjusting the pixel values of the second RGB image signals are the same as in the case of the first special image processing section 64a.

The first color information conversion unit 88 for HS space performs the first color information conversion process for HS space on the first hue H_x and first saturation S_x to obtain a second hue H_y and second saturation Convert to S_y. The first color information conversion unit 88 for the HS space is composed of a two-dimensional LUT (Look Up Table), and is based on the first hue H_x and the first saturation S_x and the first hue H_x and the first saturation S_x. A second hue H_y and a second saturation S_y obtained by performing the first color information conversion process for the HS space are stored in association with each other. Details of the first color information conversion process for the HS space will be described later.

As shown in FIG. 28A, in a first HS space (corresponding to the "first feature space" of the present invention) formed by the first saturation S_x on the vertical axis and the first hue H_x on the horizontal axis, , the first range, the second range, and the third range are distributed in the first quadrant. In this first HS space, there is a difference D12x between the first range and the second range (e.g., the average value of the first range and the average value of the second range), and the difference between the first range and the third range has a difference D13x (eg, the mean value of the first range and the mean value of the third range). The difference D12x appears as a difference in saturation between the colors in the first range and the second range on the image, and the difference D13x appears as a difference in hue between the colors in the first range and the third range on the image.

On the other hand, the second HS space formed by the second hue H_y and the second saturation S_y obtained by the first color information conversion process for the HS space (the vertical axis is the second saturation S_y and the horizontal axis is the second hue H_y) In , as shown in FIG. 28B, the first range, the second range, and the third range are distributed in positions different from those in the first HS space. In this second HS space (corresponding to the "second feature space" of the present invention), there is a difference D12y between the first range and the second range (for example, the average value of the first range and the average value of the second range ), and there is a difference D13y between the first range and the third range (eg, the average value of the first range and the average value of the third range).

The difference D12y appears as a difference in saturation and hue between the colors in the first range and the second range on the image. Also, the difference D12y is larger than the difference D12x. On the other hand, the difference D13y appears as a hue difference between the colors in the first range and the third range on the image. Also, the difference D13y is larger than the difference D13x. Furthermore, the coordinates of the first range on the second HS space are different from the coordinates of the first range on the first HS space. That is, at least one of the saturation and hue in the first range is different before and after the first color information conversion process for the HS space.

As described above, the first color information conversion process for the HS space increases the difference between the first range and the second range and the difference between the first range and the third range. The ranges may differ in saturation and/or hue. Therefore, the first special image similar to that described above can be obtained from the second hue H_y and the second saturation S_y that have undergone the first color information conversion processing for the HS space.

The second color information conversion processing for the HS space is performed by a second special image processing section (not shown) having substantially the same configuration as the first special image processing section 96a. This second special image processing section has a second color information conversion section for the HS space instead of the first color information conversion section 88 for the HS space. It is the same.

The second color information conversion unit for the HS space performs second color information conversion processing for the HS space on the first hue H_x and the first saturation S_x to obtain a second hue H_y and a second saturation S_y. Convert to The second color information conversion unit for the HS space is composed of a two-dimensional LUT (Look Up Table), and includes a first hue H_x, a first saturation S_x, and an HS based on the first hue H_x and first saturation S_x. A second hue H_y and a second saturation S_y obtained by performing the second color information conversion process for space are stored in association with each other. The details of the second color information conversion process for the HS space will be described later.

As shown in FIG. 29A, in the first HS space formed by the first saturation S_x on the vertical axis and the first hue H_x on the horizontal axis, the first range and , the second range and the third range are distributed in the first quadrant, and the difference D12x (difference in saturation) and the difference D13x (difference in hue) between the first range and the second and third ranges difference). On the other hand, in the second HS space formed with the second hue H_y and the second saturation S_y obtained by the second color information conversion process for the HS space, the first Of the second range and the third range, the second range and the third range are distributed in positions different from the first HS space. In this second HS space, there is a difference D12y between the first range and the second range, and a difference D13y between the first range and the third range.

The difference D12y appears as a difference in saturation between the colors in the first range and the second range on the image. Also, the difference D12y is larger than the difference D12x. On the other hand, the difference D13y appears as a hue difference between the colors in the first range and the third range on the image. Also, the difference D13y is larger than the difference D13x. Furthermore, the coordinates of the first range on the second HS space are the same as the coordinates of the first range on the first HS space. That is, the saturation and hue in the first range are the same before and after conversion in the second color information conversion process for the HS space. As described above, the difference between the first range and the second range and the difference between the first range and the third range are increased by the second color information conversion process for the HS space. The saturation and hue of the range can be the same. Therefore, a second special image similar to that described above can be obtained from the second hue H_y and the second saturation S_y that have undergone the second color information conversion processing for the HS space.

The first color information conversion process for the HS space consists of a first process and a second process for the HS space. First, in the first processing for the HS space, as shown in FIG. 30, the second range is translated downward in the saturation direction while the coordinates of the first and third ranges are maintained. This translation moves the second range to the reference range. The reference range is a low-saturation range that includes the origin in the first HS space and does not include the first and third ranges after the first processing for the HS space.

In the second processing for the HS space, as shown in FIG. 31, the coordinates of the second range out of the first range, the second range, and the third range after the first processing for the HS space are used as the reference range. In the maintained state, the coordinates of the first range and the third range are translated in order to separate the first range and the third range from each other. At this time, the coordinates of the first range are translated leftward with respect to the hue direction, and the coordinates of the third range are translated rightward with respect to the hue direction.

The second color information conversion process for the HS space consists of the first process and the third process for the HS space. The first processing for the HS space is the same as above. On the other hand, in the third processing for the HS space, as shown in FIG. 32, the coordinates of the second range out of the first range, the second range, and the third range after the first processing for the HS space are used as the reference. While maintaining the range and maintaining the coordinates of the first range, the coordinates of the third range are translated to the right with respect to the hue direction.

[Second embodiment]
In the second embodiment, instead of the four-color LEDs 20a to 20d shown in the first embodiment, a laser light source and phosphors are used to illuminate the observation target. Other than that, it is the same as the first embodiment.

As shown in FIG. 33, in the endoscope system 100 of the second embodiment, in the light source device 14, in place of the four-color LEDs 20a to 20d, a blue laser light source ( 33) 104 and a blue-violet laser light source (labeled "405LD" in FIG. 33) 106 that emits blue-violet laser light with a center wavelength of 405±10 nm. The light emitted from the semiconductor light emitting elements of the light sources 104 and 106 is individually controlled by the light source control unit 108, and the light amount ratio between the light emitted from the blue laser light source 104 and the light emitted from the blue-violet laser light source 106 can be changed freely. It has become.

The light source controller 108 drives the blue laser light source 104 in the normal observation mode. On the other hand, in the case of the first or second special observation mode or the simultaneous observation mode, both the blue laser light source 104 and the blue-violet laser light source 106 are driven, and the emission intensity of the blue laser light is adjusted to It is controlled to be greater than the emission intensity of light. The laser beams emitted from the light sources 104 and 106 described above enter a light guide (LG) 41 via optical members (none of which are shown) such as a condenser lens, an optical fiber, and a multiplexer.

In addition, it is preferable that the half width of the blue laser light or the blue-violet laser light is about ±10 nm. For the blue laser light source 104 and the blue-violet laser light source 106, broad area type InGaN laser diodes can be used, and InGaNAs laser diodes and GaNAs laser diodes can also be used. Further, as the light source, a light-emitting body such as a light-emitting diode may be used.

In addition to the illumination lens 45, the illumination optical system 30a is provided with a phosphor 110 on which blue laser light or blue-violet laser light from the light guide 41 is incident. Fluorescence is emitted from the phosphor 110 by irradiating the phosphor 110 with the blue laser light. Also, part of the blue laser light passes through the phosphor 110 as it is. The blue-violet laser light passes through the phosphor 110 without exciting it. The light emitted from the phosphor 110 is irradiated into the subject through the illumination lens 45 .

Here, in the normal observation mode, since blue laser light is mainly incident on the phosphor 110, the blue laser light and the fluorescence excited and emitted from the phosphor 110 by the blue laser light are combined as shown in FIG. White light illuminates the observation target. On the other hand, in the first or second special observation mode or the simultaneous observation mode, both the blue-violet laser light and the blue laser light are incident on the phosphor 110. Therefore, as shown in FIG. The inside of the specimen is irradiated with special light obtained by combining the laser light and the fluorescence excited and emitted from the phosphor 110 by the blue laser light.

Phosphor 110 is a plurality of types of phosphors (for example, YAG-based phosphors or phosphors such as BAM (BaMgAl ₁₀ O ₁₇ )) that absorb part of the blue laser light and emit green to yellow excited light. It is preferable to use one comprising As in this configuration example, if the semiconductor light emitting element is used as the excitation light source for the phosphor 110, white light with high luminous efficiency and high intensity can be obtained, and the intensity of the white light can be easily adjusted. Changes in temperature and chromaticity can be kept small.

[Third embodiment]
In the third embodiment, instead of the four-color LEDs 20a to 20d shown in the first embodiment, a broadband light source such as a xenon lamp and a rotating filter are used to illuminate the observation target. Also, instead of the color image sensor 48, a monochrome image sensor is used to capture an image of the observation target. Other than that, it is the same as the first embodiment.

As shown in FIG. 36, in the endoscope system 200 of the third embodiment, the light source device 14 is provided with a broadband light source 202, a rotating filter 204, and a filter switching section 205 instead of the four-color LEDs 20a to 20d. there is The imaging optical system 30b is provided with a monochrome imaging sensor 206 having no color filter instead of the color imaging sensor 48 .

Broadband light source 202 is a xenon lamp, a white LED, or the like, and emits white light with a wavelength range from blue to red. The rotating filter 204 has a normal observation mode filter 208 provided inside and a special observation mode filter 209 provided outside (see FIG. 37). The filter switching unit 205 moves the rotating filter 204 in the radial direction, and inserts the normal observation mode filter 208 of the rotating filter 204 into the optical path of the white light when the normal observation mode is set by the mode switching switch 13a. Then, when the first or second special observation mode is set, the special observation mode filter 209 of the rotating filter 204 is inserted into the optical path of the white light.

As shown in FIG. 37, the normal observation mode filter 208 includes, along the circumferential direction, a B filter 208a that transmits blue light out of white light, a G filter 208b that transmits green light out of white light, and a white light filter 208b. Among them, an R filter 208c for transmitting red light is provided. Therefore, in the normal observation mode, by rotating the rotating filter 204, the observation target is alternately irradiated with blue light, green light, and red light.

The special observation mode filter 209 includes, along the circumferential direction, a Bn filter 209a that transmits blue narrow-band light of a specific wavelength out of white light, a G filter 209b that transmits green light out of white light, and a filter 209b that transmits green light out of white light. Among them, an R filter 209c for transmitting red light is provided. Therefore, in the special observation mode, by rotating the rotating filter 204, the observation target is alternately irradiated with blue narrow-band light, green light, and red light.

In the endoscope system 200, in the normal observation mode, the monochrome imaging sensor 206 captures an image of the inside of the specimen each time the observation target is irradiated with blue light, green light, and red light. As a result, three-color image signals of RGB are obtained. Based on these RGB image signals, a normal image is generated in the same manner as in the first embodiment.

On the other hand, in the first or second special observation mode or the simultaneous observation mode, the inside of the specimen is imaged by the monochrome imaging sensor 206 each time the observation target is irradiated with blue narrow-band light, green light, or red light. As a result, a Bn image signal, a G image signal, and an R image signal are obtained. A first or second special image is generated based on the Bn image signal, the G image signal, and the R image signal. Instead of the B image signal, the Bn image signal is used to generate the first or second special image. Otherwise, the generation of the first or second special image is performed in the same manner as in the first embodiment.

[Fourth embodiment]
In the fourth embodiment, instead of the insertion type endoscope 12 and the light source device 14, a swallowable capsule endoscope is used to generate RGB image signals necessary for generating the normal image and the first or second special image. to get

As shown in FIG. 38, the capsule endoscope system 300 of the fourth embodiment includes a capsule endoscope 302, a transmitting/receiving antenna 304, a capsule receiving device 306, a processor device 16, and a monitor 18. . The capsule endoscope 302 includes an LED 302a, an imaging sensor 302b, an image processing section 302c, and a transmission antenna 302d. Note that the processor device 16 is the same as that of the first embodiment, but in the fourth embodiment, a mode switching switch 308 for switching between the normal observation mode, the first special observation mode, and the second special observation mode is newly provided. there is

The LEDs 302a emit white light, and a plurality of LEDs 302a are provided inside the capsule endoscope 302 . Here, as the LED 302a, it is preferable to use a white LED or the like that includes a blue light source and a phosphor that emits fluorescence by converting the wavelength of the light from the blue light source. An LD (Laser Diode) may be used instead of the LED. White light emitted from the LED 302a illuminates the observation target.

The imaging sensor 302b is a color imaging sensor that captures an image of an observation target illuminated with white light and outputs RGB image signals. Here, it is preferable to use a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor as the image sensor 302b. The RGB image signal output from the imaging sensor 302b is processed by the image processing unit 302c to be a signal that can be transmitted by the transmission antenna 302d. The RGB image signal that has passed through the image processing unit 302c is wirelessly transmitted to the transmission/reception antenna 304 from the transmission antenna 302d.

The transmitting/receiving antenna 304 is attached to the subject's body and receives RGB image signals from the transmitting antenna 302d. The transmitting/receiving antenna 304 wirelessly transmits the received RGB image signal to the capsule receiving device 306 . The capsule receiving device 306 is connected to the receiving section 53 of the processor device 16 and transmits the RGB image signals from the transmitting/receiving antenna 304 to the receiving section 53 .

Although four colors of light having emission spectra as shown in FIG. 3 are used in the above embodiment, the emission spectra are not limited to this. For example, as shown in FIG. 39, green light G and red light R have spectra similar to those in FIG. Light having a wavelength range on the slightly longer wavelength side may be used. Further, the blue light Bs may be light having a central wavelength of 445 to 460 nm and a wavelength range slightly shorter than that of the blue light B in FIG.

In the above embodiment, the angle θ is changed in the second process so that the first range and the third range are separated from each other. You can leave. For example, the first range and the third range may be separated from each other by changing the radius r, or both the radius r and the angle θ may be changed to separate the first range and the third range. You may make it leave|separate from each other. Also, in the second process, the coordinates in the first range may be moved while the coordinates in the third range are maintained.

In the above embodiment, the first B/G ratio and the first G/R ratio are obtained from the first RGB image signals, and the first signal ratio space formed by the obtained first B/G ratio and first G/R ratio is As described above, when the 1B image signal is a narrow-band signal obtained from narrow-band light with a narrow wavelength band (for example, light with a half-value width within the range of 20 nm), the wavelength band is broad-band light ( For example, the difference between the first range and the second range on the first signal ratio space, and the first range and the third There is a large difference in range. Here, the narrow-band light includes the "violet light V" and "blue light B" of the first embodiment, and the "blue laser light" or "blue-violet laser light" of the second embodiment. The "blue narrow band light" of the third embodiment is included, and the "blue light source light" of the fourth embodiment is included.

In FIG. 40, "Xn" indicates the second range when the 1B image signal is a narrowband signal, and "Xb" indicates the second range when the 1B image signal is a wideband signal. . Comparing 'Xn' and 'Xb', 'Xn' is located below 'Xb' on the first signal ratio space. "Yn" indicates the third range when the 1B image signal is a narrowband signal, and "Yb" indicates the third range when the 1B image signal is a wideband signal. Comparing 'Yn' and 'Yb', 'Yn' is located below 'Yb' in the first signal ratio space.

As shown in FIG. 40, the difference D12n between the average value AXn of "Xn" and the average value AR1 of the first range is greater than the difference D12b between the average value AXb of "Xb" and the average value AR1 of the first range. Thus, the difference D13n between the average value AYn of "Yn" and the average value AR1 of the first range is larger than the difference D13b between the average value AXb of "Yb" and the first range AR1. As described above, if the 1B image signal is a narrow-band signal, the difference between the first range and the second and third ranges is already large before performing the process of expanding and compressing the radius and angle. attached. By performing the first and second color information conversion processing for a specific feature space on the first to third ranges in such a state, the difference between the normal portion and the atrophied portion can be displayed more clearly. Become.

Note that by using a narrowband signal as the first G image signal, the difference between the first range and the second range and the difference between the first range and the third range can be calculated by using the wideband signal as the first G image signal. can be larger than for Furthermore, as described above, the first B image signal or the first G image signal is not limited to being a narrowband signal, and by making at least one color image signal out of the first RGB image signals a narrowband signal, the first The difference between the first range and the second range and the difference between the first range and the third range can be made larger than when the first RGB image signals are all broadband signals. Further, as for the narrowband signal, as described above, in addition to the signal obtained from the narrowband light, the signal obtained by the spectral estimation processing described in Japanese Patent Application Laid-Open No. 2003-93336 is also included.

It should be noted that the present invention is applicable to various medical image processing apparatuses in addition to the processor unit incorporated in the endoscope system such as the first to third embodiments and the capsule endoscope system such as the fourth embodiment. It is possible to apply

10, 100, 200 endoscope system 16 processor device (medical image processing device)
72 Signal ratio calculator 64a First special image processor 64b Second special image processor 73 First color information converter 86 for signal ratio space First color information converter 88 for CrCb space First color for HS space Information converter 77 RGB converter (color image signal converter)
81 brightness adjustment unit 85 luminance/color difference signal conversion unit 87 HSV conversion unit

Claims (10)

A signal conversion unit that converts the first RGB signal into a second RGB signal through color information conversion processing,
A first quadrant of a first ab space formed by first elements a ^* _x and b ^* _x obtained by Lab-converting a first RGB signal, and the color information conversion for the first elements a ^* _x and b ^* _x. The first range, the second range, and the third range are distributed in the second ab space formed by the second elements a ^* _y and b ^* _y obtained after the processing,
a difference D12y between the first range and the second range in the secondab space becomes larger than a difference D12x between the first range and the second range in the firstab space by the color information conversion process; Further, a difference D13y between the first range and the third range in the secondab space is made larger than a difference D13x between the first range and the third range in the firstab space by the color information conversion processing. become,
In the color information conversion process, the first range in the second ab space is made different in at least one of saturation and hue from the first range in the first ab space,
The difference D12x is a difference in saturation, the difference D13x is a difference in hue, the difference D12y is a difference in saturation and hue, and the difference D13y is a difference in hue. 2. The medical image processing apparatus according to claim 1, wherein the first range, the second range, and the third range are observation targets within the subject. In the color information conversion process, for each of the first range, the second range, and the third range distinguished by the hue and saturation, the first range, the second range, and the 3. The medical image processing apparatus according to claim 1 or 2, wherein the processing is a process of transferring to the first range, the second range, and the third range of conversion destinations associated with , and the third range. The color information conversion process includes
In the polar coordinate transformed space, for each of the first range, the second range, and the third range distinguished by the radius or angle, the first range, the second range, and 3. The medical image processing apparatus according to claim 1, wherein said third range is a process of transferring to said first range, said second range, and said third range of conversion destinations associated with said third range. 5. The medical image processing apparatus according to any one of claims 1 to 4, comprising a light source device that emits blue light, green light, and red light, at least one of which is narrowband light, toward the subject. 6. The medical image processing apparatus according to claim 5, wherein said blue light, said green light, and said red light are obtained by allowing light with a wavelength range from blue to red to pass through each filter of a rotating filter. 7. The medical image processing apparatus according to claim 6, wherein the light with a wavelength range from blue to red is light emitted from a xenon lamp or a white LED. 6. The medical image processing apparatus according to claim 5, wherein said light source device comprises a blue semiconductor light source emitting said blue light, a green semiconductor light source emitting said green light, and a red semiconductor light source emitting said red light. 6. The medical image processing apparatus according to claim 5, wherein the blue light, the green light, and the red light are alternately applied to the subject, and the subject is imaged by a monochrome imaging sensor. a mode switching unit for switching between a plurality of observation modes with different types of images to be displayed on the display unit;
10. The medical image processing apparatus according to any one of claims 1 to 9, wherein at least one observation mode among the plurality of observation modes displays the image that has undergone color information conversion processing on the display unit.

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