JP6659817B2 - Medical image processing equipment - Google Patents

Description

  The present invention relates to a medical image processing apparatus that generates an image in which a difference in color between a normal part and a lesion is emphasized.

  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, illumination light is emitted from the endoscope to the observation target, and the observation target is illuminated with the illumination light based on an image signal obtained by imaging the observation target with the imaging element of the endoscope. Is displayed 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, such as a lesion protruding greatly from the mucous membrane surface, having a shape or size that is significantly different from that of a normal portion. However, for a diseased part whose shape or size is almost the same as that of a normal part, a color difference from the normal part is detected as a clue. In this case, if the lesion has not progressed so much and there is almost no difference in color from the normal part, it becomes extremely difficult to detect.

  Therefore, in Patent Literature 1, the part where the blood volume (hemoglobin index) deviates from the reference value is further processed to depart from the reference value so that the color difference between the normal part and the lesion part becomes clear. ing.

Japanese Patent No. 3228627

  It is known that stomach mucosa atrophy occurs in the stomach mucosa, and the mucous membrane of the stomach changes to a fading tone. Therefore, the atrophy part in which atrophy has occurred in the mucous membrane has a different color from the normal part in which no atrophy has occurred. By observing the difference in color from the normal part with an endoscope, it is diagnosed whether gastric cancer is present (there is an ABC screening recommended by the NPO Japan Gastric Cancer Prediction, Diagnosis and Treatment Research Organization). .

  Here, when atrophy has advanced to a high degree (for example, when it is included in the C group or D group in the ABC examination), since the color difference between the normal part and the atrophy part is clear, the atrophy part is easily detected. It is possible to However, when atrophy is in progress (for example, in the case of being included in the B group or C group in the ABC examination), since the color difference between the atrophy part and the normal part is slight, the atrophy part is only caused by the color difference. Is difficult to detect. Therefore, even when the color difference between the atrophy part and the normal part is slight, such as during atrophy progression, the color difference between the normal part and the atrophy part is emphasized, and the detection of the atrophy part is easily performed. Is required.

  In addition, it is possible to emphasize the color difference between the atrophy part and the normal part by the method of Patent Document 1. However, the color of the atrophy part is affected not only by the blood volume but also by factors other than the blood volume, and it is difficult to emphasize the color difference between the atrophy part and the normal part by the method of Patent Document 1.

  An object of the present invention is to provide a medical image processing apparatus that generates an image in which a color difference between an abnormal part such as an atrophy part in which a gastric mucosa has atrophied and a normal part is emphasized.

A medical image processing apparatus according to the present invention includes a light source device that emits blue light, green light, and red light, at least one of which is narrow-band light, toward a subject, and a first color image signal obtained by imaging the subject. And an image signal input processing unit for inputting a pixel value of a second color image signal obtained through the color information conversion process, based on first brightness information obtained from the first color image signal. An image having undergone the color information conversion process is displayed on the display unit, and the color information conversion process converts the color information obtained from the first color image signal into a conversion destination associated with the range before the conversion. The first range, the second range, and the third range distributed in the color space are included in the range, and the color information conversion process includes the saturation and the hue of the first range before and after the conversion. Are different, and the converted The difference D12y between the range and the second range is made larger than the difference D12x between the first range and the second range before the conversion, and the difference D13y between the first range and the third range after the conversion is calculated as The first color information conversion processing to make the difference larger than the difference D13x between the first range and the third range
In a process in which the saturation and hue of the first range are the same before and after the conversion, the difference D12y between the first range and the second range after the conversion is calculated by comparing the difference D12y between the first range and the second range before the conversion. The difference D13x between the first range and the third range after the conversion is larger than the difference D13x between the first range and the third range before the conversion. This is one of the second color information conversion processes.

  The color information conversion process is preferably a process of maintaining the color difference between the first range and the third range, and shifting the range so that the color difference between the first range and the second range increases. The color information conversion process is preferably a process in which a range before each conversion is moved to a destination range in a space subjected to polar coordinate conversion. In the space converted in the polar coordinates, it is preferable that the saturation be converted by moving in the radial direction, and the hue be converted by moving in the angular direction. In the first special image obtained by the first color information conversion processing in the color information conversion processing, it is preferable that the boundary between the normal part and the abnormal part is clearly represented. In the second special image obtained by the second color information conversion process in the color information conversion process, it is preferable that the color of the normal part is represented by the original color of the living body.

  It is preferable that the blue light, the green light, and the red light are obtained by transmitting each of the filters of the rotating filter in the light whose wavelength range is from blue to red. The light whose wavelength range extends from blue to green is preferably light emitted from a xenon lamp or a white LED. The light source device preferably includes 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. The subject is preferably irradiated with the blue light, the green light, and the red light alternately, and the subject is preferably imaged by a monochrome imaging sensor. A mode switching unit is provided for switching a plurality of observation modes in which types of images to be displayed on the display unit are different from each other, and at least one of the plurality of observation modes displays an image on which color information conversion processing has been performed on the display unit. Is preferably displayed.

The medical image processing apparatus of the present invention is a light source device that emits blue light, green light, and red light toward a subject, and the blue light, green light, and red light have a wavelength range from blue to red. A light source device obtained by transmitting each filter of the rotation filter out of the light, an image signal input processing unit for input processing a first color image signal obtained by imaging the subject, and a color information conversion process A brightness adjustment unit that adjusts the pixel value of the second color image signal based on the first brightness information obtained from the first color image signal, and the image after the color information conversion processing is displayed on the display unit. The color information conversion process is a process of moving color information obtained from a first color image signal to a range of a conversion destination associated with a range before conversion, and the range includes a first range distributed in a color space. Range, a second range, and a third range, The information conversion process is a process in which either the saturation or the hue of the first range is different before and after the conversion, and the difference D12y between the first range and the second range after the conversion is calculated by the first range before the conversion. The difference D13x between the first range and the third range after the conversion is larger than the difference D13x between the first range and the third range before the conversion. One-color information conversion processing, or processing in which the saturation and hue of the first range are the same before and after conversion, and the difference D12y between the first range after conversion and the second range is determined by the first range before conversion. The difference D13x between the first range and the third range after the conversion is larger than the difference D13x between the first range and the third range before the conversion. This is one of two-color information conversion processing.

  ADVANTAGE OF THE INVENTION According to this invention, the image which emphasized the color difference between the abnormal part, such as the atrophy part which the gastric mucosa atrophied, and the normal part can be emphasized.

It is an outline view of an endoscope system of a first embodiment. It is a block diagram showing the function of the endoscope system of a 1st embodiment. 5 is a graph showing emission spectra of violet light V, blue light B, green light G, and red light R. FIG. 3 is a block diagram illustrating functions of a first special image processing unit. FIG. 9 is an explanatory diagram illustrating a first color information conversion process for a signal ratio space. FIG. 9 is an explanatory diagram showing a first color information conversion process for ab space. FIG. 9 is an explanatory diagram illustrating a first process. 6 is a graph showing a relationship between a moving radius r and a moving radius Er. FIG. 9 is an explanatory diagram illustrating an operation and an effect obtained by a first process for a signal ratio space. FIG. 9 is an explanatory diagram illustrating an operation and an effect obtained by a first process for ab space. FIG. 9 is an explanatory diagram illustrating a second process for a signal ratio space. It is a graph which shows the movement range of angle (theta) in angle change range R2. 11 is a graph illustrating a relationship between an angle θ and an angle Eθ after a second process for a signal ratio space. FIG. 11 is an explanatory diagram illustrating an operation and an effect obtained by a second process for a signal ratio space. FIG. 14 is an explanatory diagram illustrating an operation and an effect obtained by a second process for the ab space. FIG. 9 is an explanatory diagram illustrating a second color information conversion process for a signal ratio space. FIG. 9 is an explanatory diagram illustrating a second color information conversion process for ab space. FIG. 11 is an explanatory diagram illustrating a third process for a signal ratio space. It is a graph which shows the movement range of angle (theta) in angle change range R3. 11 is a graph showing a relationship between an angle θ and an angle Eθ after a third process for a signal ratio space. FIG. 10 is an explanatory diagram illustrating an operation and an effect obtained by a third process for a signal ratio space. FIG. 14 is an explanatory diagram illustrating an operation and an effect obtained by a third process for ab space. FIG. 11 is an image diagram of a monitor that simultaneously displays a first special image and a second special image. It is a flowchart which shows a series of flows of the present invention. It is a block diagram showing the function of the 1st special image processing part which has the 1st color information conversion part for CrCb space. FIG. 4 is an explanatory diagram illustrating a first color information conversion process for a CrCb space. FIG. 9 is an explanatory diagram illustrating a second color information conversion process for a CrCb space. FIG. 4 is an explanatory diagram showing a first process for a CrCb space. FIG. 9 is an explanatory diagram illustrating a second process for the CrCb space. FIG. 10 is an explanatory diagram showing a third process for the CrCb space. FIG. 3 is a block diagram illustrating functions of a first special image processing unit having a first color information conversion unit for an HS space. FIG. 4 is an explanatory diagram illustrating a first color information conversion process for an HS space. FIG. 9 is an explanatory diagram illustrating a second color information conversion process for an HS space. FIG. 4 is an explanatory diagram illustrating a first process for an HS space. FIG. 9 is an explanatory diagram showing a second process for the HS space. FIG. 10 is an explanatory diagram showing a third process for the HS space. It is a block diagram showing the function of the endoscope system of a 2nd embodiment. It is a graph which shows the emission spectrum of white light. It is a graph which shows the emission spectrum of special light. It is a block diagram showing the function of the endoscope system of a 3rd embodiment. It is a top view showing a rotation filter. It is a figure showing the function of the capsule endoscope system of a 4th embodiment. 4 is a graph showing emission spectra of violet light V, blue light B, green light G, and red light R different from FIG. The positions of the second range and the third range on the first signal ratio space when the first B image signal is a narrowband signal and the positions on the first signal ratio space when the first B image signal is a wideband signal It is explanatory drawing which shows the position of a 2nd range and a 3rd range.

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

  The operation unit 12b is provided with a mode switching SW 13a in addition to the angle knob 12e. The mode switching SW 13a is used for switching 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 a normal image is displayed on the monitor 18. The first special observation mode is a mode for displaying a first special image on the monitor 18 for observing a boundary between an atrophy part and a normal part where atrophy occurs in the gastric mucosa due to a lesion such as gastric cancer. The second special observation mode is a mode for displaying a second special image on the monitor 18 for observing a color difference between the atrophy part and the normal part. The simultaneous observation mode is used for simultaneously observing the boundary between the atrophy part and the normal part and observing the color difference between the atrophy part and the normal part, and displays the first special image and the second special image on the monitor 18. This is a mode for simultaneous display.

  The processor device 16 is electrically connected to a monitor 18 and a console 19. The monitor 18 outputs and displays image information and the like. The console 19 functions as a UI (User Interface) for receiving an input operation such as a function setting. Note that 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 a V-LED (Violet Light Emitting Diode) 20a, a B-LED (Blue Light Emitting Diode) 20b, a G-LED (Green Light Emitting Diode) 20c, and an R-LED (Red). Light Emitting Diode) 20d, a light source control unit 21 for controlling the driving of these four-color LEDs 20a to 20d, and an optical-path coupling unit 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 unit 23 is radiated into the subject via the light guide 41 and the illumination lens 45 inserted into the insertion unit 12a. Note that an LD (Laser Diode) may be used instead of the LED.

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

  The light source controller 21 controls the V-LED 20a, the B-LED 20b, the G-LED 20c, and the R-LED 20d in any of the normal observation mode, the first special observation mode, the second special observation mode, and the simultaneous observation mode. Lights up. Therefore, light obtained by mixing four colors of the violet light V, the blue light B, the green light G, and the red light R is irradiated on the observation target. In the normal observation mode, the light source control unit 21 controls the LEDs 20a to 20d such that the light amount ratio among the violet light V, the blue light B, the green light G, and the red light R becomes 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 determines that the light amount ratio between the violet light V, the blue light B, the green light G, and the red light R is Vs: Bs: The LEDs 20a to 20d are controlled so that Gs: Rs.

  As shown in FIG. 2, the light guide 41 is built in the endoscope 12 and the universal cord (cord connecting the endoscope 12 with the light source device 14 and the processor device 16). The coupled light propagates to the end 12 d of the endoscope 12. Note that a multimode fiber can be used as the light guide 41. As an example, a thin fiber cable having a core diameter of 105 μm, a cladding diameter of 125 μm, and a diameter of 0.3 to 0.5 mm including a protective layer serving as an outer cover can be used.

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

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

  The image sensor 48 is a so-called complementary color image sensor having complementary color filters of C (cyan), M (magenta), Y (yellow) and G (green) instead of the RGB color image sensor. May be. When a complementary color image sensor is used, image signals of four colors of CMYG are output. Therefore, it is necessary to convert four color image signals of CMYG into three color image signals of RGB by complementary color-primary color conversion. . Further, the image sensor 48 may be a monochrome image sensor having no 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 perform a synchronization process in the processing of the imaging signal.

  The image signal output from the image sensor 48 is transmitted to the CDS / AGC circuit 50. The CDS / AGC circuit 50 performs correlated double sampling (CDS (Correlated Double Sampling)) and automatic gain control (AGC (Auto Gain Control)) on an image signal that is an analog 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 unit 53, a DSP (Digital Signal Processor) 56, a noise removing unit 58, an image processing switching unit 60, a normal image processing unit 62, a special image processing unit 64, a video signal generation unit 66. The receiving unit 53 receives a digital RGB image signal 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. Corresponding to the signal to be transmitted.

  The DSP 56 performs various kinds of signal processing such as defect correction processing, offset processing, gain correction processing, linear matrix processing, gamma conversion processing, and demosaic processing on the received image signal. In the defect correction processing, the signal of the defective pixel of the image sensor 48 is corrected. In the offset processing, a dark current component is removed from the RGB image signal subjected to the defect correction processing, and an accurate zero level is set. In the gain correction processing, the signal level is adjusted by multiplying the RGB image signal after the offset processing by a specific gain. The RGB image signal after the gain correction processing is subjected to a linear matrix processing for improving color reproducibility. Thereafter, brightness and saturation are adjusted by gamma conversion processing. Demosaic processing (also referred to as isotropic processing or synchronization processing) is performed on the RGB image signal after the linear matrix processing, and a signal of a color insufficient for each pixel is generated by interpolation. By this demosaic processing, all pixels have signals of RGB colors.

  The noise removing unit 58 removes noise from the RGB image signal by performing a noise removing process (for example, a moving average method, a median filter method, or the like) on the RGB image signal that has been subjected to gamma correction or the like by the DSP 56. The RGB image signal from which noise has been removed is transmitted to the image processing switching unit 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.

  When the normal observation mode is set by the mode switching SW 13a, the image processing switching unit 60 transmits the RGB image signals to the normal image processing unit 62, and performs the first special observation mode, the second special observation mode, If the mode is set to the observation mode, an RGB image signal is transmitted to the special image processing unit 64.

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

  The special image processing unit 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. A simultaneous display image processing unit 64c for generating a simultaneous display special image for simultaneous display. However, the first special image processing unit 64a does not generate the second special image. 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 unit 64 are input to the video signal generation unit 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 to be displayed on the monitor 18 as an image. Based on the video signal, the monitor 18 displays a normal image, a first special image, or a 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 a signal ratio space, An RGB conversion unit 77, a structure enhancement unit 78, an inverse Log conversion unit 79, and a gamma conversion unit 80 are provided. Further, the first special image processing unit 64a includes a brightness adjustment unit 81 between the RGB conversion unit 77 and the structure enhancement unit 78.

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

  The Log conversion unit 71 performs a Log conversion on each of the first RGB image signals (corresponding to the “first color image signal” of the present invention). As a result, an R image signal after log conversion (logR), a G image signal after log conversion (logG), and a B image signal after log conversion (logB) are obtained. The signal ratio calculation unit 72 (corresponding to the “color information acquisition unit” of the present invention) performs difference processing (logG−logB = logG / B = −log (B) based on the log-converted G image signal and B image signal. / 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" indicates a value obtained by omitting "-log" from -log (B / G). Further, by performing a difference process (logR-logG = logR / G = -log (G / R)) on the basis of the log-converted R image signal and G image signal, the first G / R ratio (" 1 signal ratio Nx "). The first G / R ratio, as in the case of the first B / G ratio, indicates a value obtained by omitting "-log" from -log (G / R). Hereinafter, the two-dimensional color space formed by the first B / G ratio and the first G / R ratio is referred to as “first signal ratio space (corresponding to“ first feature space ”of the present invention)”.

  Note that the first B / G ratio and the first G / R ratio are obtained from the pixel values of the pixels at the same position in the B image signal, the G image signal, and the R image signal. The first B / G ratio and the first G / R ratio are obtained for each pixel. Further, since the first B / G ratio has a correlation with the blood vessel depth (the distance from the mucosal surface to the position where the specific blood vessel is located), if the blood vessel depth is different, the first B / G ratio also changes accordingly. I do. Further, since the first G / R ratio is correlated with the blood volume (hemoglobin index), if there is a change in the blood volume, the first G / R ratio also changes accordingly.

  The first color information conversion unit 73 for the signal ratio space performs a first color information conversion process for the signal ratio space on the first B / G ratio and the first G / R ratio obtained by the signal ratio calculation unit 72. To a second B / G ratio and a second G / R ratio. The second B / G ratio corresponds to the “second signal ratio My” of the present invention, and the second G / R ratio corresponds to the “second signal ratio Ny” of the present invention. The first color information conversion unit 73 for the signal ratio space is configured by a two-dimensional LUT (Look Up Table), and includes a first B / G ratio, a first G / R ratio, a first B / G ratio, and a first G / R. The second B / G ratio and the 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 the signal ratio space will be described later.

  As shown in FIG. 5 (A), in a first signal ratio space in which the vertical axis is the first B / G ratio and the horizontal axis is the first G / R ratio, a first range in which normal mucous membrane is distributed; A second range in which the atrophic mucosa atrophied by atrophic gastritis is distributed, and a third range in which deep blood vessels that are present under the atrophic mucosa atrophyed by atrophic gastritis and see through with atrophy are distributed in the first quadrant. ing. In the first signal ratio space, there is a difference D12x (for example, the average value of the first range and the average value of the second range) between the first range and the second range. Is a difference D13x (for example, the average value of the first range and the average value of the third range). The difference D12x appears on the image as a saturation difference for colors in the first and second ranges, and the difference D13x appears on the image as a hue difference for colors in the first and third ranges.

  In FIG. 5A, “first” indicates “first range”, “second” indicates “second range”, and “third” indicates “third range”. The notations “first” to “third” are the same in the following drawings. In FIG. 5A, “first” is omitted from “first B / G ratio” on the vertical axis, and “first” is omitted from “first G / R ratio” on the horizontal axis. ing. Similar omissions are made in the following drawings.

  On the other hand, a 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 represents the second B / G ratio, and the horizontal axis represents 5B, the first range, the second range, and the third range are distributed, as in the first signal ratio space, as shown in FIG. 5B. In the second signal ratio 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 of the first range and the average of the second range) Value), and there is a difference D13y (for example, the average value of the first range and the average value of the third range) between the first range and the third range.

  The difference D12y appears on the image as a difference between saturation and hue for the colors in the first range and the second range, and the difference D12y is larger than the difference D12x. In addition, the difference D13y appears as a hue difference between the colors in the first range and the third range on the image similarly to the difference D13x, 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, before and after the conversion of the first color information conversion process for the signal ratio space, at least one of the saturation and the hue of the first range is different.

  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 the first color information conversion process for the signal ratio space is performed. Before and after the conversion of the color information conversion processing, at least one of the saturation and the hue of the first range is different. Thereby, 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 atrophy is caused by atrophy under the atrophy mucosa and under the atrophy mucosa. The boundary between the atrophied part where the deep blood vessels and the like that are being viewed and the normal part where the normal mucous membrane is present is clearly displayed.

In addition, first elements a ^* _x, b ^* _x (in the CIE Lab space) obtained by performing Lab conversion on the first RGB image signal with a Lab conversion unit (not shown, corresponding to the “color information acquisition unit” of the present invention). The color components a ^* and b ^* are expressed in the same manner. The same applies to the first color information conversion process for the ab space similar to the first color information conversion process for the signal ratio space. The same operation and effect as described above can be obtained.

Here, FIG. 6A shows the distribution of the first to third ranges on the first ab 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. The difference D12y between the first range and the second range and the difference D13y between the first range and the third range are shown. As shown in FIG. 6, the difference between the first range and the second range and the difference between the first range and the third range can be increased by the first color information conversion processing for the ab space. The first ab space corresponds to the “first feature space” of the present invention, and the second ab space corresponds to the “second feature space” of the present invention.

  The RGB conversion unit 77 (corresponding to the “color image signal conversion unit” of the present invention) uses at least one of the first RGB image signals and uses the first color information conversion unit 73 for the signal ratio space. Are converted to a second RGB image signal (corresponding to the “second color image signal” of the present invention). For example, the RGB conversion unit 77 converts the second B / G ratio into a second B image signal by performing an operation based on the G image signal and the second B / G ratio among the first RGB image signals. Further, the RGB converter 77 converts the second G / R ratio into a second R image signal by performing an operation based on the G image signal and the second G / R ratio among the first RGB image signals. Further, the RGB conversion unit 77 outputs the first G image signal as a second G image signal without performing any special conversion.

  The brightness adjustment unit 81 adjusts the pixel value of the second RGB image signal using the first RGB image signal and the second RGB image signal. The reason why the brightness adjusting unit 81 adjusts the pixel value of the second RGB image signal is as follows. Since the second RGB image signal is 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, the brightness may be significantly different from the brightness of the first RGB image signal. There is. Therefore, the brightness adjustment unit 81 adjusts the pixel value of the second RGB image signal so that the second RGB image signal after the brightness adjustment has the same brightness as the first RGB image signal.

The brightness adjustment unit 81 includes a first brightness information calculation unit 81a that obtains first brightness information Yin based on a first RGB image signal, and a second brightness that obtains second brightness information Yout based on a second RGB image signal. And an information calculation unit 81b. The first brightness information calculation unit 81a calculates the first brightness information Yin according to an arithmetic expression of “kr × pixel value of first R image signal + kg × pixel value of first G image signal + kb × pixel value of first B image signal”. Is calculated. Similarly to the first brightness information calculation unit 81a, the second brightness information calculation unit 81b calculates the second brightness information Yout according to the same arithmetic expression as described above. When the first brightness information Yin and the second brightness information Yout are obtained, the brightness adjusting unit 81 calculates the pixel value of the second RGB image signal by performing an operation 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
Note that “R ^* ” represents a second R image signal after brightness adjustment, “G ^* ” represents a second G image signal after brightness adjustment, and “B ^* ” represents a second B image signal after brightness adjustment. ing. “Kr”, “kg”, and “kb” are arbitrary constants in the range of “0” to “1”.

  The structure enhancement unit 78 performs a structure enhancement process on the second RGB image signal after the brightness adjustment by the brightness adjustment unit 81. As the structure enhancement processing, frequency filtering or the like is used. The inverse Log conversion unit 79 performs an inverse Log conversion on the second RGB image signal that has passed through the structure enhancement unit 78. As a result, a second RGB image signal having a true pixel value is obtained. The gamma converter 80 performs gamma conversion on the second RGB image signal that has passed through the inverse Log converter 79. As a result, 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 unit 80 is sent to the simultaneous display image processing unit 64c or the video signal generation unit 66 as the RGB image signal of the first special image.

  The first color information conversion processing for the signal ratio space includes polar coordinate conversion processing, first processing and second processing for the signal ratio space, and orthogonal coordinate conversion processing. First, the first B / G ratio and the first G / R ratio obtained by the signal ratio calculator 72 are converted into a moving radius r and an angle θ by performing a polar coordinate conversion process. Next, a first process for the signal ratio space is performed. As shown in FIG. 7, on the first signal ratio space, the moving radius r of the coordinates P1 within the moving radius changing range R1 is changed, and the moving radius of the coordinates outside the moving radius changing range R1 is not changed. The moving radius change range R1 is such that the moving radius r is in a range from “rA” to “rB”, and the angle θ is in a range from “θA” to “θB” (rA <rB, θA <θB). . The radial change range R1 is a region including the second range in which the atrophic mucosa atrophied by atrophic gastritis is distributed, and is present under the first range in which the normal mucosa is distributed and under the atrophy mucosa atrophyed by atrophic gastritis. , And a third range in which deep blood vessels that are seen through with atrophy are distributed.

  In the first process for the signal ratio space, the angle θ of the coordinates of the radius change range R1 is not changed. In the first process 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 that is larger than “1”. A compression process for performing an extension process for changing the radius r at a radius change rate Vy having a radius change rate smaller than “1” when the radius r is within a range from “rA” to “rp”. It is preferred to do so. In addition, when the moving radius change rate is “1”, the size of the moving radius r does not change even if the process of changing the moving radius r is performed.

  By performing the above-described first process for the signal ratio space, as shown in FIG. 8, the moving radius r within the moving radius change range R1 is changed to the moving radius Er smaller than the moving radius r. Further, the moving radius change rate is represented by a slope of a “straight line L1” indicating a tangent to a line CV1 relating the moving radius r and the moving radius Er, and within a range of “rp” to “rB”, While the slope is larger than “1”, the slope of the straight line L1 is smaller than “1” from “rA” to “rp”. On the other hand, the moving radius r outside the moving radius change range R1 is converted into a moving radius Er whose size does not change from the moving radius r (identity conversion). Outside the radius change range R1, the inclination of the straight line L1 is "1".

  As shown in FIG. 9A, before the first process for the signal ratio space, the first range, the second range, and the third range are close to each other, but the first process for the signal ratio space is performed. After that, as shown in FIG. 9B, only the coordinates of the second range are moved to the reference range including the origin while keeping the coordinates of the first range and the third range as they are. The reference range is a low chroma 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, the coordinates of the first range and the third range are not changed by the first processing for the ab space as shown in FIG. While maintaining the state, only 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 process for the signal ratio space, as shown in FIG. 11A, while changing the angle θ of the coordinates P2 within the angle change range R2, the angle θ is changed for coordinates outside the angle change range R2. Absent. The angle change range R2 is set to include the first range and the third range. In the second process for the signal ratio space, the moving radius 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 the angle θc. In the second process for the signal ratio space in the angle change range R2, the angle θ that is equal to or less than the angle θc is rotated clockwise while the angle θ is equal to or more than the angle θc. Is rotated counterclockwise. For the angle θ of the fixed range R2x from the first center line CL1, an extension process of changing the angle change rate at an angle change rate Wx larger than “1” is performed, and the angle θ of the range R2y exceeding the range R2x is determined. It is preferable to perform a compression process of changing the angle change rate Wy at an angle change rate smaller than “1”. Further, by the second process for the signal ratio space, the coordinates of the angle change range R2 are set to a range of ± 90 degrees from the first center line CL1 (in the signal ratio space, the horizontal axis of “positive” is set to 0 ° and the angle is set to When expressed from 0 ° to 360 °, it is preferable to move within a range P (see FIG. 11B) from “270 ° + θc” to “θc + 90 °”. If the angle change rate is “1”, the magnitude of the angle θ does not change even if the process of changing the angle θ is performed.

  By performing the above-described second process for the signal ratio space, as shown in FIG. 12, the angle θ that is equal to or smaller than the angle θc within the angle change range R2 is changed to the angle Eθ that is smaller than the angle θ. On the other hand, the angle θ that is equal to or larger than the angle θc is changed to an angle Eθ that is larger than the angle θ. Further, the angle change rate is represented by a slope of a “line L2” indicating a tangent to a line CV2 that relates the angle θ to the angle Eθ. Although the slope of the line L2 is larger than “1” in the range R2x. On the other hand, within the range R2y, the inclination of the straight line L2 is smaller than “1”. On the other hand, the angle θ outside the angle change range R2 is converted into an angle Eθ whose size does not change from the angle θ (identity conversion). Outside the angle change range R2, the inclination of the straight line L2 is "1".

  As shown in FIG. 13A (A), before the second process 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 different from each other. Approaching each other. After the second process for the signal ratio space, as shown in FIG. 13A (B), most of the coordinates of the first range are kept in the second range of the signal ratio space while the coordinates of 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 process for the signal ratio space is completed, the orthogonal coordinate conversion process is performed on the second radius r and the angle θ after the second process for the signal ratio space. Thereby, the second B / G ratio and the 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 in the reference range by the second processing for the ab space as shown in FIG. 13B. In this state, most of the coordinates of the first range move to the second quadrant of the second ab space, while most of the coordinates of the third range move to the fourth quadrant of the second ab 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. It is preferable that the brightness adjustment unit 81 adjusts the pixel value of the second RGB image signal obtained after the first and second processes for the ab space. The method of adjusting the pixel value of the second RGB image signal is the same as described above.

  The second special image processing unit 64b has substantially the same configuration as the first special image processing unit 64a, but replaces the first color information conversion unit 73 for the signal ratio space with a second color for the signal ratio space. It has an information conversion unit (not shown). The second color information conversion unit for the signal ratio space performs a second color information conversion process for the signal ratio space on the first B / G ratio and the first G / R ratio obtained by the signal ratio calculation unit 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 includes a two-dimensional LUT (Look Up Table), and includes a first B / G ratio, a first G / R ratio, and a first B / G ratio and a first G / R ratio. The second B / G ratio and the second G / R ratio obtained by performing the second color information conversion processing for the signal ratio space based on the above are stored in association with each other. The details of the second color information conversion processing for the signal ratio space will be described later.

  As shown in FIG. 14A, in a first signal ratio space in which the vertical axis is the first B / G ratio and the horizontal axis is the first G / R ratio, the first range, the second range, and the While three ranges are distributed, there is a difference D12x (for example, the average value of the first range and the average value of the second range) between the first range and the second range, and the first range and the third range are different. 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 process for the signal ratio space (the vertical axis is the second B / G ratio, and the horizontal axis is the second signal ratio space) In the (2G / R ratio), as shown in FIG. 14B, similarly to the first signal ratio space, the first range, the second range, and the third range are distributed. In the second signal ratio space, there is a difference D12y (for example, the average value of the first range and the average value of the second range) between the first range and the second range, and the difference between the first range and the third range. There is a difference D13y between them (for example, the average value of the first range and the average value of the third range).

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

  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 the difference between the second range and the second range for the signal ratio space. Before and after the conversion of the color information conversion process, the saturation and the hue of the first range are the same. Thereby, in 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, the color of the normal part is displayed while being maintained, The atrophic mucosa in the atrophic part where atrophic gastritis has occurred is displayed in a fading tone. Further, on the second special image, the color of the deep blood vessel, which is being seen through by atrophy under the atrophy mucous membrane, changes from red to a color such as magenta, so that it can be clearly displayed. Therefore, since the second special image is displayed in the original color when atrophic gastritis occurs, the color difference between the normal part and the atrophic part is clear.

If the plurality of pieces of first color information are the first elements a ^* _x and b ^* _x, the second color information for the signal ratio space is used for the first elements a ^* _x and b ^* _x. By performing the second color information conversion process for the ab space similar to the conversion process, the same operation and effect as described above can be obtained.

Here, FIG. 15A shows the distribution of the first to third ranges in the first ab 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. The difference D12y between the first range and the second range and the 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 maintained while the coordinates of the first range are maintained by the second color information conversion process for the ab space. Can be increased.

  The second color information conversion processing for the signal ratio space includes polar coordinate conversion processing, first processing and third processing for the signal ratio space, and orthogonal coordinate conversion processing. The polar coordinate conversion processing, the first processing for the signal ratio space, and the orthogonal coordinate conversion processing are the same as those described above, and thus description thereof will be omitted.

  In the third process for the signal ratio space, based on the moving radius r and the angle θ after the first process for the signal ratio space, by changing the angle θ, the third range is maintained while maintaining the coordinates of the first range. A third process for the signal ratio space for moving the coordinates is performed. In the third process for the signal ratio space, as shown in FIG. 16A, while changing the angle θ of the coordinate P3 within the angle change range R3, the angle θ is changed for coordinates outside the angle change range R3. Absent. The angle change range R3 is set to include the third range and not include the first range. In the third process for the signal ratio space, the moving radius r of the coordinates of the angle change range R3 is not changed.

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

  By performing the above-described third processing for the signal ratio space, the angle θ is changed to an angle Eθ smaller than the angle θ within the angle change range R3, as shown in FIG. Further, the angle change rate is represented by a slope of a “line L3” indicating a tangent to a line CV3 that relates the angle θ to the angle Eθ, and the slope of the line L3 is larger than “1” in the range R3x. On the other hand, within the range R3y, the inclination of the straight line L3 is smaller than “1”. On the other hand, the angle θ outside the angle change range R3 is converted into an angle Eθ whose size does not change from the angle θ (identity conversion). Outside the angle change range R3, the inclination of the straight line L3 is "1".

  As shown in FIG. 18A, before the third process 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 mutually separated. It is approaching. After the third process for the signal ratio space, as shown in FIG. 18A (B), while maintaining the coordinates of the second range in the reference range and maintaining the coordinates of the first range without changing, Most of the coordinates of the three ranges move to the fourth quadrant of the signal ratio space. The movement of the coordinates of the third range from the first quadrant to the fourth quadrant corresponds to changing the hue on the second special image while maintaining the saturation. Thereby, the coordinates of the first range, the second range, and the third range are completely separated.

Even when the plurality of pieces of first color information are the first elements a ^* _x and b ^* _x, as shown in FIG. 18B, the third process for ab space sets the coordinates of the second range as the reference range. Most of the coordinates of the third range move to the fourth quadrant of the second ab space while maintaining the coordinates of the first range without changing the coordinates. 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. It is preferable that the brightness adjustment unit 81 adjusts the pixel value of the second RGB image signal obtained after the first and third processes for the ab space. The method of adjusting the pixel value of the second RGB image signal is the same as described above.

  The simultaneous display image processing unit 64c generates a special image for simultaneous display 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. The first special image is an image that makes it easy to grasp the position of the atrophy part because the boundary between the normal part and the atrophy part is extremely clear, but the normal part is not the original color of the mucous membrane of the stomach. Since the images are displayed in a pseudo color, the images are uncomfortable for the doctor. On the other hand, in the second special image, when compared with the first special image, the boundary between the normal part and the atrophied part is somewhat clear, and the color of the normal part is displayed in the original stomach color. The image has no discomfort. By displaying these two first special images and the second special image simultaneously, it is possible to detect the boundary between the normal part and the atrophy part while grasping the color of the normal part.

  Next, a series of flows of the present invention will be described with reference to the flowchart of FIG. First, the normal observation mode is set, and the insertion section 12a of the endoscope 12 is inserted into the sample. When the distal end 12d of the insertion section 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 first B / G ratio and the first G / R ratio are calculated by the signal ratio calculation unit 72 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 unit 73 for the signal ratio space sets the first B / G ratio and the first G / R ratio to the first ratio for the signal ratio space. The one-color information conversion process converts the data into 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 the monitor 18.

  On the other hand, when the second special observation mode is set, the first B / G ratio and the first G / R ratio are converted into the second color information for the signal ratio space by the second color information conversion unit for the signal ratio space. The information is converted into a second B / G ratio and a second G / R ratio by an information conversion process. 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 the monitor 18.

  The simultaneous observation mode is not limited to the simultaneous display of the first special image and the second special image, but may be, for example, the simultaneous display of the first special image and the normal image. Further, the second special image and the normal image may be displayed simultaneously. In this case, a display image is generated by each of the normal image processing unit 62 and the special image processing unit 64, and is displayed on the monitor 18 via the video signal generation unit 66.

  In the simultaneous observation mode, the first special image and the third special image that does not perform any of the first color information conversion processing and the second color information conversion processing for the signal ratio space are displayed simultaneously. Is also good. The third special image is generated by a third special image processing unit (not shown) provided in the special image processing unit 64. The third special image processing unit in this case is different from the first and second special image processing units 64a and 64b in that the signal ratio space necessary for the first color information conversion process and the second color information conversion process for the signal ratio space is used. The first color information conversion unit and the second color information conversion unit are not provided. Other than that, it is the same as the first and second special image processing units 64a and 64b. When the third special image is generated, it is preferable that the light intensity of the violet light V be higher than the light intensity of the blue light B, the green light G, and the red light R to emit light of each color. The third special image obtained under such a light emission condition is an image in which surface blood vessels are emphasized and displayed while the entire image remains bright.

  In the above embodiment, the first B / G ratio and the first G / R ratio are obtained from the first RGB image signal by the signal ratio calculation unit 72, and the first B / G ratio and the first G / R ratio are used for the signal ratio space. Although the first and second color information conversion processes convert the image data into the second B / G ratio and the second G / R ratio, the first RGB image signal is converted into a plurality of first B / G ratios different from the first G / R ratio. Color information may be obtained, and the plurality of pieces of first color information may be converted into a plurality of pieces of second color information by first and second color information conversion processes for a specific feature space.

  For example, the 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 performed on 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 unit 94a shown in FIG. The first special image processing unit 94a is different from the first special image processing unit 64a in that the inverse gamma conversion unit 70, the Log conversion unit 71, the signal ratio calculation unit 72, the first color information conversion unit 73 for the signal ratio space, and the inverse The log converter 79 and the gamma converter 80 are not provided. Instead, the first special image processing unit 94a includes a luminance / color difference signal conversion unit 85 and a first color information conversion unit 86 for CrCb space. Other than that, the first special image processing unit 94a is the same as the first special image processing unit 64a.

  The luminance / color difference signal conversion unit 85 (corresponding to the “color information acquisition unit” of the present invention) converts the first RGB image signal into a luminance signal Y and first color difference signals Cr_x, Cb_x. A well-known conversion formula is used for conversion into 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 converter 86 for the CrCb space. The luminance signal Y is sent to the RGB conversion unit 77 and the brightness adjustment unit 81. The RGB conversion unit 77 converts the second color difference signals Cr_y and Cb_y and the luminance signal Y that have been subjected to the first color information conversion processing for the CrCb space into second RGB image signals. The brightness adjustment unit 81 uses the luminance 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, and performs the second RGB The pixel value of the image signal is adjusted. The method of calculating the second brightness information Yout and the method of adjusting the pixel value of the second RGB image signal are the same as those in the case of the first special image processing unit 64a.

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

  As shown in FIG. 22A, in a 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, a first range and a second range are set. , And a third range are distributed in the second quadrant. In the first CrCb space, there is a difference D12x (for example, the average value of the first range and the average value of the second range) between the first range and the second range, and the difference D12x between the first range and the third range. Has a difference D13x (for example, the average value of the first range and the average value of the third range). The difference D12x appears as a saturation difference on the image with respect to the colors of the first range and the second range on the image, and the difference D13x is a difference between the hues on the image with respect to the colors of the first and third ranges on the image. It appears 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 process for the CrCb space, as shown in FIG. The third ranges are each distributed in a separate quadrant. In the 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 (for example, the average value of the first range and the average value of the third range) between the first range and the third range.

  The difference D12y appears on the image as a difference between saturation and hue for the colors in the first range and the second range. 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. The difference D13y is larger than the difference D13x. Further, 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, before and after conversion in the first color information conversion process for the CrCb space, at least one of the saturation and the hue of the first range is different.

  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, and the first color information conversion process is performed before and after the conversion process. At least one of the saturation and the hue of the range can be different. Therefore, a first special image similar to the above can be obtained from the second color difference signals Cr_y and Cb_y after the first color information conversion processing for the CrCb space.

  The second color information conversion process for the CrCb space is performed by a second special image processing unit (not shown) having substantially the same configuration as the first special image processing unit 94a. The second special image processing unit 94a is different from the first special image processing unit 94a except that it has a second color information conversion unit for CrCb space instead of the first color information conversion unit 86 for CrCb space. The same is true.

  The second color information conversion unit for the CrCb space performs a second color information conversion process for the 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 second color information conversion unit for the CrCb space includes a two-dimensional LUT (Look Up Table), and includes first color difference signals Cr_x and Cb_x, and second color information for the CrCb space based on the first color difference signals Cr_x and Cb_x. The second color difference signals Cr_y and Cb_y obtained by performing the information conversion process 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, Cb_x, as in FIG. 22A, the first range, the second range, and the third range Are distributed in the second quadrant, and have 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 process for the CrCb space, the first range and the second range are as shown in FIG. Although distributed in the same second quadrant, only the third range is distributed in the first quadrant. In the second CrCb space, there is a difference D12y between the first range and the second range, and there is a difference D13y between the first range and the third range.

  The difference D12y appears on the image as a difference in saturation between colors in the first range and the second range. 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. The difference D13y is larger than the difference D13x. Further, 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, before and after the conversion in the second color information conversion process for the CrCb space, the saturation and the hue of the first range are the same.

  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, and the first color information is converted before and after the conversion process. The saturation and hue of the range can be the same. Therefore, a second special image similar to the above can be obtained from the second color difference signals Cr_y and Cb_y after the second color information conversion processing for the CrCb space.

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

  In the second process for the CrCb space, as shown in FIG. 25, in order to separate the coordinates of the first range and the third range from each other while maintaining the second range in the reference range, the first range and the third range are used. Processing is performed to move three ranges. The method of moving the first range and the third range is the same as the case of the second process for the signal ratio space, and is performed by expanding and compressing the angle. The moving radius 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 processing for the CrCb space includes polar coordinate conversion processing, first and third processing for the CrCb space, and rectangular coordinate conversion processing. The polar coordinate conversion processing, the first processing for the CrCb space, and the orthogonal coordinate conversion processing are the same as in the case of the first color information conversion processing for the CrCb space.

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

  Further, a hue H (Hue) and a saturation S (Saturation) are obtained as color information, and first and second color information conversion processing for HS space is performed on the hue H (Hue) and the saturation S (Saturation). You may. The first color information conversion process for the HS space is performed by the first special image processing unit 96a shown in FIG. The first special image processing unit 96a is different from the first special image processing unit 64a in that the inverse gamma conversion unit 70, the Log conversion unit 71, the signal ratio calculation unit 72, the first color information conversion unit 73 for the signal ratio space, and the inverse The log converter 79 and the gamma converter 80 are not provided. Instead, the first special image processing unit 96a includes an HSV conversion unit 87 and a first color information conversion unit 88 for HS space. Other than that, the first special image processing unit 96a is the same as the first special image processing unit 64a.

  The HSV conversion unit 87 (corresponding to the “color information acquisition unit” of the present invention) converts the first RGB image signal into a first hue H_x, a first saturation S_x, and lightness V. A well-known conversion formula is used for the conversion into the first hue H_x, the first saturation S_x, and the lightness V. The first hue H_x and the first saturation S_x are sent to the first color information conversion unit 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 lightness V of the HS space subjected to the first color information conversion processing into a second RGB image signal. In the brightness adjustment section 81, the first brightness information obtained by the first brightness information calculation section 81a as the first brightness information Yin, and the second brightness information calculation section 81b obtains the second brightness information Yout. The pixel value of the second RGB image signal is 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 value of the second RGB image signal are the same as those of the first special image processing unit 64a.

  The first color information conversion unit 88 for the HS space performs a first color information conversion process for the HS space on the first hue H_x and the first saturation S_x, and obtains a second hue H_y and a second saturation. Convert to S_y. The first color information conversion unit 88 for the HS space includes a two-dimensional LUT (Look Up Table), and is based on the first hue H_x, the first saturation S_x, and the first hue H_x and the first saturation S_x. The second hue H_y and the 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) in which the vertical axis is the first saturation S_x and the horizontal axis is the first hue H_x. , A first range, a second range, and a third range are distributed in the first quadrant. In the first HS space, there is a difference D12x (for example, the average value of the first range and the average value of the second range) between the first range and the second range, and the difference D12x between the first range and the third range. Has a difference D13x (for example, the average value of the first range and the average value of the third range). The difference D12x appears on the image as a saturation difference for colors in the first and second ranges, and the difference D13x appears on the image as a hue difference for colors in the first and third ranges.

  On the other hand, the second hue H_y obtained by the first color information conversion process for the HS space and the second HS space formed by the second saturation S_y (the vertical axis is the second saturation S_y, and the horizontal axis is the second hue H_y) In FIG. 28, as shown in FIG. 28B, the first range, the second range, and the third range are distributed at positions different from the first HS space. In the second HS 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 (for example, the average value of the first range and the average value of the third range).

  The difference D12y appears on the image as a difference between saturation and hue for the colors in the first range and the second range. 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. The difference D13y is larger than the difference D13x. Further, 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, before and after the conversion of the first color information conversion process for the HS space, at least one of the saturation and the hue of the first range is different.

  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 HS space, and the first color information conversion process is performed before and after the conversion process. At least one of the saturation and the hue of the range can be different. Therefore, a first special image similar to the above can be obtained from the second hue H_y and the second saturation S_y after the first color information conversion processing for the HS space.

  The second color information conversion process for the HS space is performed by a second special image processing unit (not shown) having substantially the same configuration as the first special image processing unit 96a. The second special image processing unit 96a is different from the first special image processing unit 96a except that it has a second color information conversion unit for HS space instead of the first color information conversion unit 88 for HS space. The same is true.

  The second color information conversion unit for the HS space performs a second color information conversion process for the HS space on the first hue H_x and the first saturation S_x, and performs a second hue H_y and a second saturation S_y. Convert to The second color information conversion unit for the HS space is configured by 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 the first saturation S_x. The second hue H_y and the second saturation S_y obtained by performing the space second color information conversion process 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 in which the vertical axis is the first saturation S_x and the horizontal axis is the first hue H_x, the first range is the same as in FIG. 28A. , A second range and a third range are distributed in the first quadrant, and a difference D12x (difference in saturation) and a difference D13x (a difference in hue) between the first range, the second range, and the third range. Difference). On the other hand, in the second HS space formed by the second hue H_y and the second saturation S_y obtained by the second color information conversion process for the HS space, as shown in FIG. Of the two ranges and the third range, the second range and the third range are distributed at positions different from the first HS space. In the second HS space, there is a difference D12y between the first range and the second range, and there is a difference D13y between the first range and the third range.

  The difference D12y appears on the image as a difference in saturation between colors in the first range and the second range. 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. The difference D13y is larger than the difference D13x. Further, 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, before and after the conversion of the second color information conversion process for the HS space, the saturation and the hue of the first range are the same. 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 processing for the HS space, and the first color information is converted before and after the conversion processing. The saturation and hue of the range can be the same. Therefore, a second special image similar to the above can be obtained from the second hue H_y and the second saturation S_y after the second color information conversion processing for the HS space.

  The first color information conversion process for the HS space includes a first process and a second process for the HS space. First, in the first process for the HS space, as shown in FIG. 30, while maintaining the coordinates of the first and third ranges, the second range is translated downward with respect to the saturation direction. This parallel movement moves the second range to the reference range. The reference range is a low chroma range that includes the origin on the first HS space and does not include the first and third ranges after the first processing for the HS space.

  In the second process for the HS space, as shown in FIG. 31, the coordinates of the second range among the first range, the second range, and the third range after the first process for the HS space are set as the reference range. While maintaining the coordinates, 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 to the left with respect to the hue direction, and the coordinates of the third range are translated to the right with respect to the hue direction.

  The second color information conversion process for the HS space includes a first process and a third process for the HS space. The first process for the HS space is the same as described above. On the other hand, in the third process for the HS space, as shown in FIG. 32, the coordinates of the second range among the first range, the second range, and the third range after the first process for the HS space are used as a reference. While maintaining the range and 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, the observation target is illuminated by using a laser light source and a phosphor instead of the four-color LEDs 20a to 20d shown in the first embodiment. Otherwise, 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, instead of the four-color LEDs 20 a to 20 d, a blue laser light source that emits blue laser light having a center wavelength of 445 ± 10 nm (see FIG. In FIG. 33, a blue-violet laser light source (shown as “405LD” in FIG. 33) 104 that emits a blue-violet laser light having a center wavelength of 405 ± 10 nm is provided. The light emission from the semiconductor light emitting elements of these 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. It has become.

  The light source control unit 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 changed to the blue-violet laser light. It is controlled so as to be higher than the light emission intensity. The laser light emitted from each of the light sources 104 and 106 is incident on the light guide (LG) 41 via optical members (none are shown) such as a condenser lens, an optical fiber, and a multiplexer.

  Note that the half width of the blue laser light or the blue-violet laser light is preferably set to about ± 10 nm. As the blue laser light source 104 and the blue-violet laser light source 106, a broad-area InGaN-based laser diode can be used, and an InGaNAs-based laser diode or a GaNAs-based laser diode can also be used. Further, a configuration using a light emitting body such as a light emitting diode may be used as the light source.

  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. When the phosphor 110 is irradiated with the blue laser light, the phosphor 110 emits fluorescence. Some blue laser light passes through the phosphor 110 as it is. The blue-violet laser light is transmitted without exciting the phosphor 110. The light emitted from the phosphor 110 is applied to the inside of the sample via the illumination lens 45.

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

The phosphor 110 absorbs a part of the blue laser light and emits green to yellow light by excitation light emission (for example, a phosphor such as a YAG phosphor or a phosphor such as BAM (BaMgAl ₁₀ O ₁₇ )). It is preferable to use a material including When a semiconductor light emitting element is used as an excitation light source for the phosphor 110 as in this configuration example, high intensity white light can be obtained with high luminous efficiency, the intensity of the white light can be easily adjusted, and the color of the white light can be easily adjusted. Changes in temperature and chromaticity can be kept small.

[Third embodiment]
In the third embodiment, the observation target is illuminated using a broadband light source such as a xenon lamp and a rotating filter instead of the four-color LEDs 20a to 20d shown in the first embodiment. Further, instead of the color image sensor 48, an image of the observation target is imaged by a monochrome image sensor. Otherwise, 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 includes a broadband light source 202, a rotating filter 204, and a filter switching unit 205 instead of the four-color LEDs 20a to 20d. I have. The imaging optical system 30b is provided with a monochrome imaging sensor 206 having no color filter, instead of the color imaging sensor 48.

  The broadband light source 202 is a xenon lamp, a white LED, or the like, and emits white light having a wavelength range from blue to red. The rotary filter 204 includes 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 rotary filter 204 in the radial direction, and inserts the normal observation mode filter 208 of the rotary filter 204 into the optical path of white light when set to the normal observation mode by the mode switch SW13a. Then, when set to the first or second special observation mode, the special observation mode filter 209 of the rotary filter 204 is inserted into the optical path of white light.

  As shown in FIG. 37, the normal observation mode filter 208 includes a B filter 208a that transmits blue light among white light, a G filter 208b that transmits green light among white light, and a white light along the circumferential direction. Among them, an R filter 208c that transmits red light is provided. Accordingly, in the normal observation mode, the rotation filter 204 rotates, so that the observation target is irradiated with the blue light, the green light, and the red light alternately.

  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 among white light, a G filter 209b that transmits green light among white light, and a white light Among them, an R filter 209c that transmits red light is provided. Therefore, in the special observation mode, the rotation of the rotation filter 204 causes the blue narrow band light, the green light, and the red light to be alternately applied to the observation target.

  In the endoscope system 200, in the normal observation mode, the monochrome imaging sensor 206 takes an image of the inside of the subject every time blue light, green light, and red light are irradiated on the observation target. As a result, image signals of three colors of RGB are obtained. Then, based on the 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 monochrome imaging sensor 206 captures an image of the inside of the subject every time the blue narrow band light, the green light, and the red light are irradiated on the observation target. As a result, a Bn image signal, a G image signal, and an R image signal are obtained. The first or second special image is generated based on the Bn image signal, the G image signal, and the R image signal. For generating the first or second special image, a Bn image signal is used instead of the B image signal. Otherwise, the first or second special image is generated in the same manner as in the first embodiment.

[Fourth embodiment]
In the fourth embodiment, a swallowable capsule endoscope is used instead of the insertion type endoscope 12 and the light source device 14, and the 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, the processor device 16, and the monitor 18. . The capsule endoscope 302 includes an LED 302a, an image sensor 302b, an image processing unit 302c, and a transmission antenna 302d. The processor device 16 is the same as in the first embodiment, but in the fourth embodiment, a mode switching SW 308 for switching between the normal observation mode, the first special observation mode, and the second special observation mode is newly provided. I have.

  The LED 302 a emits white light, and a plurality of LEDs 302 a are provided in the capsule endoscope 302. Here, as the LED 302a, it is preferable to use a white LED or the like including 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. The white light emitted from the LED 302a illuminates the observation target.

  The image sensor 302b is a color image sensor, and 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 image sensor 302b is subjected to a process by the image processing unit 302c to make the signal transmittable by the transmission antenna 302d. The RGB image signal that has passed through the image processing unit 302c is wirelessly transmitted from the transmission antenna 302d to the transmission / reception antenna 304.

  The transmission / reception antenna 304 is attached to the body of the subject, and receives the RGB image signal from the transmission 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 unit 53 of the processor device 16 and transmits an RGB image signal from the transmitting / receiving antenna 304 to the receiving unit 53.

  In the above embodiment, four colors of light having an emission spectrum as shown in FIG. 3 are used, but the emission spectrum is not limited to this. For example, as shown in FIG. 39, the green light G and the red light R have the same spectrum as that of FIG. 3, while the violet light Vs has a center wavelength of 410 to 420 nm, which is smaller than that of the violet light V of FIG. Light having a wavelength range on the longer wavelength side may be used. The blue light Bs may have a center wavelength of 445 to 460 nm and have a wavelength range slightly shorter than the blue light B in FIG.

  In the above-described embodiment, the angle θ is changed in the second processing so that the first range and the third range are separated from each other. However, the first range and the third range are separated from each other by another method. They may be separated. For example, the first range and the third range may be separated from each other by changing the moving radius r, and the first range and the third range may be changed by changing both the moving radius r and the angle θ. They may be separated from each other. Further, in the second process, the coordinates of the first range may be moved while maintaining the coordinates of the third range.

  In the above embodiment, the first B / G ratio and the first G / R ratio are obtained from the first RGB image signal, and the first signal ratio space formed by the obtained first B / G ratio and first G / R ratio is obtained. As described above, when the first B image signal is a narrow-band signal obtained from narrow-band light having a narrow wavelength band (for example, light having a half-value width in a range of 20 nm), the wavelength band is broadband light ( For example, the difference between the first range and the second range in the first signal ratio space, and the difference between the first range and the third range in the first signal ratio space are compared with the case of a broadband signal obtained from light having a half width exceeding 20 nm. The difference with the range is large. Here, the narrow-band light includes “violet light V” and “blue light B” of the first embodiment, and includes “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 a second range when the first B image signal is a narrowband signal, and “Xb” indicates a second range when the first B image signal is a wideband signal. . When “Xn” and “Xb” are compared, “Xn” is located below “Xb” in the first signal ratio space. “Yn” indicates a third range when the first B image signal is a narrow band signal, and “Yb” indicates a third range when the first B image signal is a wide band signal. When “Yn” and “Yb” are compared, “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 larger than the difference D12b between the average value AXb of “Xb” and the average value AR1 of the first range. 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 first B 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 processes for the specific feature space on the first to third ranges in such a state, the difference between the normal part and the atrophy part can be displayed more clearly. Become.

  In addition, by making the first G image signal a narrow band signal, the difference between the first range and the second range and the difference between the first range and the third range are determined in the same manner as described above. Can be made larger than in the case of Further, as described above, the first B image signal or the first G image signal is not limited to a narrow band signal, and the image signal of at least one color of the first RGB image signal is converted to a narrow band signal, 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 wideband signals. Further, as described above, the narrow-band signal includes a signal obtained from the spectral estimation processing described in JP-A-2003-93336, in addition to the signal obtained from the narrow-band light.

  The present invention can be applied to various types of medical image processing apparatuses, in addition to an endoscope system as in the first to third embodiments and a processor device incorporated in a capsule endoscope system as in the fourth embodiment. It is possible to apply.

10, 100, 200 Endoscope system 16 Processor device (medical image processing device)
72 signal ratio calculation unit 64a first special image processing unit 64b second special image processing unit 73 first color information conversion unit 86 for signal ratio space first color information conversion unit 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 (11)

A light source device that emits blue light, green light, and red light, at least one of which is narrow-band light, toward the subject,
An image signal input processing unit that performs input processing of a first color image signal obtained by imaging the subject;
A brightness adjustment unit that adjusts a pixel value of a second color image signal obtained through the color information conversion processing based on first brightness information obtained from the first color image signal;
The image after the color information conversion processing is displayed on a display unit,
The color information conversion process is a process of moving color information obtained from the first color image signal to a conversion destination range associated with a range before conversion,
The range includes a first range, a second range, and a third range distributed on a color space,
The color information conversion processing includes:
This is a process in which one of the saturation and the hue of the first range is different before and after the conversion, and a difference D12y between the first range and the second range after the conversion is compared with the first range before the conversion. The difference D13x between the first range and the third range after the conversion is made larger than the difference D13x between the first range and the third range before the conversion. First color information conversion processing to increase
In a process in which the saturation and hue of the first range are the same before and after the conversion, the difference D12y between the first range and the second range after the conversion is calculated by comparing the difference D12y between the first range and the second range before the conversion. The difference D13x between the first range and the third range after the conversion is larger than the difference D13x between the first range and the third range before the conversion. A medical image processing device that is one of the second color information conversion processes . The color information conversion processing, in polar coordinates transformed space, the medical image processing apparatus according to claim 1, wherein range before the conversion is a process proceeds in the range of the destination. 3. The medical image processing apparatus according to claim 2, wherein in the space subjected to the polar coordinate conversion, the saturation is converted by moving in the radial direction, and the hue is converted by moving in the angular direction. The first special image obtained by the first color information conversion processing, medical image processing apparatus of claims 1 to 3 any one of claims boundary of the normal portion and the abnormal portion is expressed clearly. The medical image processing apparatus according to any one of claims 1 to 4, wherein the second special image obtained by the second color information conversion processing has a normal part color represented by an original color of a living body. The medical image processing according to any one of claims 1 to 5 , wherein the blue light, the green light, and the red light are obtained by transmitting respective filters of a rotation filter among lights whose wavelength ranges from blue to red. apparatus. 7. The medical image processing apparatus according to claim 6, wherein the light whose wavelength range extends from blue to green is light emitted from a xenon lamp or a white LED. The light source device,
A blue semiconductor light source that emits the blue light, a green semiconductor light source that emits the green light, the medical image processing apparatus according to any one of claims 1 to 5 and a red semiconductor light source which emits the red light. The blue light, the green light, and the red light, the irradiated alternately to the subject, the subject is a medical image processing apparatus according to claim 1 to 8 any one imaged by the monochrome image sensor of . A mode switching unit for switching between a plurality of observation modes in which the types of images displayed on the display unit are different,
It said plurality of at least one of the observation modes of the observation mode, the color information conversion processed medical image processing apparatus of claims 1 to display on the display unit an image 9 any one of claims. Blue light, green light, and a light source device that emits red light toward the subject, the blue light, the green light, and the red light, the wavelength range of the light ranging from blue to red rotation filter A light source device obtained by transmitting each filter;
An image signal input processing unit that performs input processing of a first color image signal obtained by imaging the subject;
A brightness adjustment unit that adjusts a pixel value of a second color image signal obtained through the color information conversion processing based on first brightness information obtained from the first color image signal;
The image after the color information conversion processing is displayed on a display unit,
The color information conversion process is a process of moving color information obtained from the first color image signal to a conversion destination range associated with a range before conversion,
The range includes a first range, a second range, and a third range distributed on a color space,
The color information conversion processing includes:
This is a process in which one of the saturation and the hue of the first range is different before and after the conversion, and a difference D12y between the first range and the second range after the conversion is compared with the first range before the conversion. The difference D13x between the first range and the third range after the conversion is made larger than the difference D13x between the first range and the third range before the conversion. First color information conversion processing to increase
In a process in which the saturation and hue of the first range are the same before and after the conversion, the difference D12y between the first range and the second range after the conversion is calculated by comparing the difference D12y between the first range and the second range before the conversion. The difference D13x between the first range and the third range after the conversion is larger than the difference D13x between the first range and the third range before the conversion. A medical image processing device that is one of the second color information conversion processes .

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