Medical image processing device, endoscope system, and working method of medical image processing device

Abstract

The present invention provides a medical image processing device and an endoscope system and a working method of the medical image processing device that can also give color differences to abnormal parts buried in low-saturation areas or high-saturation areas. The saturation emphasis processing unit (76) of the present invention performs specific saturation emphasis processing on a high-saturation range located on the high-saturation side relative to a saturation baseline (SLs) in a feature space and a low-saturation range located on the low-saturation side relative to the saturation baseline (SLs). The output value contained in the low-saturation range after the specific saturation emphasis processing is larger than the input value contained in the low-saturation range before the specific saturation emphasis processing. The output value contained in the high-saturation range after the specific saturation emphasis processing is smaller than the input value contained in the high-saturation range before the specific saturation emphasis processing.

Description

Technical Field

[0001] The present invention relates to a medical image processing device and an endoscope system for processing a medical image obtained by photographing an observation object in a subject, and an operating method of the medical image processing device. Background Art

[0002] In recent years, endoscope systems including a light source device, an endoscope, and a processor device have been widely used in the medical field. In the endoscope system, illumination light is irradiated from the endoscope to the observation object, and the image of the observation object is displayed on a display based on the RGB image signal obtained by photographing the illuminated observation object using the imaging element of the endoscope under the illumination light.

[0003] In recent years, for example, a process of emphasizing the color difference between a normal part and an abnormal part such as atrophic gastritis is performed on an image of an observation object obtained by an endoscope as shown in Patent Document 1. This color difference emphasizing process makes it easier to understand the difference between the normal part and the abnormal part.

[0004] Patent Document 1: Japanese Patent No. 5647752

[0005] There are also abnormal parts embedded in low-saturation areas or high-saturation areas. For example, when a brown lesion is mixed in a red background mucosa or an inflammatory disease such as ulcerative colitis is red, the background mucosa and the lesion have the same hue, so it is difficult to detect the lesion from the background mucosa. Therefore, it is required to give a color difference to the abnormal part embedded in the low-saturation area or high-saturation area so that it can be easily detected. Summary of the invention

[0006] The object of the present invention is to provide a medical image processing device, an endoscope system, and an operating method of the medical image processing device that can easily detect abnormal parts buried in low-saturation areas or high-saturation areas by giving color differences.

[0007] The medical image processing device of the present invention comprises: an image signal input unit, which inputs a color image signal; a color information acquisition unit, which acquires multiple color information from the color image signal; and a chroma emphasis processing unit, which performs specific chroma emphasis processing on a high chroma range located on the high chroma side relative to a chroma baseline and a low chroma range located on the low chroma side relative to the chroma baseline in a feature space formed by multiple color information, wherein the output value contained in the low chroma range after the specific chroma emphasis processing is larger than the input value contained in the low chroma range before the specific chroma emphasis processing, and the output value contained in the high chroma range after the specific chroma emphasis processing is smaller than the input value contained in the high chroma range before the specific chroma emphasis processing.

[0008] Preferably, the chroma emphasis processing unit performs a normal chroma emphasis processing different from the specific chroma emphasis processing, the output value included in the low chroma range after the normal chroma emphasis processing is smaller than the input value included in the low chroma range before the normal chroma emphasis processing, and the output value included in the high chroma range after the normal chroma emphasis processing is larger than the input value included in the high chroma range before the normal chroma emphasis processing.

[0009] Preferably, the apparatus comprises a mode switching unit for manually switching between specific saturation emphasis processing and normal saturation emphasis processing. Preferably, the apparatus comprises a saturation emphasis processing switching unit for switching to specific saturation emphasis processing when the index value obtained from the color image signal satisfies a first condition indicating low saturation or high saturation, and switching to normal saturation emphasis processing when the index value satisfies a second condition indicating intermediate saturation. Preferably, the saturation emphasis processing unit shifts the saturation reference line according to the mucous membrane color obtained from the color image signal.

[0010] Preferably, it also has: a hue emphasis processing unit, which performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs general hue emphasis processing different from the specific hue emphasis processing.

[0011] Preferably, the color image signal includes a blue signal, a green signal, and a red signal, and the plurality of color information includes a first signal ratio of the blue signal to the green signal and a second signal ratio of the green signal to the red signal. Preferably, the plurality of color information includes color difference signals Cr and Cb obtained from the color image signal. Preferably, the plurality of color information includes a hue H and a chroma S obtained from the color image signal.

[0012] The endoscope system of the present invention has the medical image processing device of the present invention described above, and has a display unit that displays at least any one of a specific chroma emphasis image obtained from a color image signal that has been subjected to a specific chroma emphasis processing, a normal chroma emphasis image obtained from a color image signal that has been subjected to a normal chroma emphasis processing, or a normal chroma image obtained from a color image signal that has not been subjected to either a specific chroma emphasis processing or a normal chroma emphasis processing.

[0013] The working method of the medical image processing device of the present invention comprises: a step of inputting a color image signal to an image signal input part; a step of a color information acquisition part acquiring multiple color information from the color image signal; and a step of a chroma emphasis processing part performing specific chroma emphasis processing on a high chroma range located on the high chroma side relative to a chroma baseline and a low chroma range located on the low chroma side relative to the chroma baseline in a feature space formed by multiple color information, wherein in the step of performing specific chroma emphasis processing, an output value included in the low chroma range after the specific chroma emphasis processing is larger than an input value included in the low chroma range before the specific chroma emphasis processing, and an output value included in the high chroma range after the specific chroma emphasis processing is smaller than an input value included in the high chroma range before the specific chroma emphasis processing.

[0014] Effects of the Invention

[0015] According to the present invention, even an abnormal portion or the like buried in a low chroma area or a high chroma area is given a color difference, thereby making it easy to detect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is an external view of the endoscope system according to the first embodiment.

[0017] Figure 2 It is a block diagram showing the functions of the endoscope system according to the first embodiment.

[0018] Figure 3 It is a graph showing the emission spectra of purple light V, blue light B, green light G and red light R.

[0019] Figure 4 This is a block diagram showing the function of a special image processing unit used when the feature space is a signal ratio space.

[0020] Figure 5 It is an explanatory diagram showing the range of normal mucosa, atrophic mucosa, deep blood vessels, RA, and redness, which show the distribution of signal ratio in space.

[0021] Figure 6 It is an explanatory diagram showing the radius vector change range Rm.

[0022] Figure 7 Graph showing the relationship between the radius r and the radius Rx(r) after normal saturation emphasis processing.

[0023] Figure 8 Graph showing the relationship between the radius r and the radius Ry(r) after a specific saturation enhancement process.

[0024] Fig. 9 It is an explanatory diagram showing the angle change range Rn.

[0025] Fig.10 : is a graph showing the relationship between the angle θ and the angle Fx(θ) after the normal hue emphasis process.

[0026] Fig.11 : is a graph showing the relationship between the angle θ and the angle Fy(θ) after the specific hue emphasis process.

[0027] Fig.12 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the normal saturation emphasis process in the signal ratio space.

[0028] Fig.13 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the specific saturation emphasis processing in the signal ratio space.

[0029] Fig.14 These are explanatory diagrams showing the distribution of normal mucosa, atrophic mucosa, deep blood vessels, BA, and redness before and after the general saturation emphasis processing and the specific hue emphasis processing in the signal ratio space.

[0030] Fig.15 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the normal saturation emphasis process in the ab space.

[0031] Fig.16 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the specific saturation emphasis process in the ab space.

[0032] Fig.17 A flowchart showing the process of the special observation mode.

[0033] Fig.18 This is a block diagram showing the functions of a special image processing section including a saturation emphasis processing switching section.

[0034] Fig.19 3 is an explanatory diagram showing regions RL, RM, and RL for determining index values.

[0035] Fig. 20 It is an explanatory diagram showing the displacement of the chroma reference line SLs.

[0036] Fig.21 This is a block diagram showing the function of the special image processing unit used when the feature space is the CrCb space.

[0037] Fig. 22 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the normal saturation emphasis process in the CrCb space.

[0038] Fig.23This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the specific saturation emphasis process in the CrCb space.

[0039] Fig.24 This is a block diagram showing the function of the special image processing unit used when the feature space is the HS space.

[0040] Fig.25 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the normal saturation emphasis process in the HS space.

[0041] Fig.26 This is an explanatory diagram showing the positional relationship between the low-saturation area and the high-saturation area before and after the specific saturation emphasis process in the HS space.

[0042] Fig. 27 It is a block diagram showing the functions of the endoscope system according to the second embodiment.

[0043] Fig.28 A graph showing the emission spectrum of white light.

[0044] Fig.29 A graph showing the emission spectrum of special light.

[0045] Fig.30 It is a block diagram showing the functions of the endoscope system according to the third embodiment.

[0046] Fig.31 A top view showing a rotating filter.

[0047] Fig.32 It is a diagram showing the function of the capsule endoscope system according to the fourth embodiment.

[0048] Fig.33 To express Figure 3 Graphs of the emission spectra of different purple light V, blue light B, green light G and red light R.

[0049] Fig.34 This is a block diagram showing the function of the special image processing unit when using a two-dimensional LUT. DETAILED DESCRIPTION

[0050] [First embodiment]

[0051] like Figure 1As shown, the endoscope system 10 of the first embodiment includes an endoscope 12, a light source device 14, a processor device 16, a display 18, and a user interface 19. The endoscope 12 is optically connected to the light source device 14 and electrically connected to the processor device 16. The endoscope 12 includes an insertion portion 12a inserted into a subject, an operation portion 12b provided at the base end portion of the insertion portion 12a, a bending portion 12c provided at the distal end side of the insertion portion 12a, and a distal end portion 12d. By operating the angle knob 12e of the operation portion 12b, the bending portion 12c performs a bending action. With this bending action, the distal end portion 12d is directed to a desired direction.

[0052] In addition to the angle button 12e, the operation unit 12b is provided with a mode switch SW13a. The mode switch SW13a (mode switch unit) is used for switching between the normal observation mode and the special observation mode. The special observation mode is a mode in which a special image is displayed on the display 18. In addition, as a mode switch unit for switching the mode, a foot switch may be used in addition to the mode switch SW13a.

[0053] The special images include the following three types: a normal saturation emphasized image, which is processed by normal saturation emphasis to emphasize the saturation difference or hue difference between the normal mucosa and the abnormal part such as brown lesions or inflammatory diseases such as ulcerative colitis; a specific saturation emphasized image, which is processed by specific saturation emphasis to emphasize the saturation difference or hue difference between the normal mucosa and the abnormal part, and emphasizes the color close to the normal mucosa and the abnormal part included in the low saturation area and the high saturation area; and a normal saturation image, which is not processed by normal saturation emphasis and specific saturation emphasis. At least one of the normal saturation emphasized image, the specific saturation emphasized image, and the normal saturation image is displayed on the display 18.

[0054] The display switching of the normal chroma emphasized image, the specific chroma emphasized image, or the normal chroma image is performed automatically or manually. The manual display switching is performed by operating the mode switching SW13a. That is, the normal chroma emphasized mode in which the normal chroma emphasized image is displayed on the display 18, the specific chroma emphasized mode in which the specific chroma emphasized image is displayed on the display 18, and the normal chroma mode in which the normal chroma emphasized image is displayed on the display 18 are switched by the mode switching SW13a.

[0055] The processor device 16 is electrically connected to a display 18 and a user interface 19. The display 18 outputs display image information, etc. The user interface 19 includes a keyboard and a mouse, etc., and has a function of accepting input operations such as function settings. In addition, an external recording unit (not shown) that records image information, etc. may be connected to the processor device 16.

[0056] like Figure 2As shown, the light source device 14 includes: a light source control unit 21, which controls the driving of four color LEDs 20a to 20d, namely, V-LED (Violet Light Emitting Diode: purple light emitting diode) 20a, B-LED (Blue Light Emitting Diode: blue light emitting diode) 20b, G-LED (Green Light Emitting Diode: green light emitting diode) 20c, and R-LED (Red Light Emitting Diode: red light emitting diode) 20d; and an optical path coupling unit 23, which couples 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 irradiated into the subject via the light guide 41 and the illumination lens 45 inserted into the insertion part 12a. In addition, LD (Laser Diode: laser diode) can also be used instead of LED.

[0057] like Figure 3 As shown, V-LED 20a generates purple light V with a central wavelength of 405±10nm and a wavelength range of 380 to 420nm. B-LED 20b generates blue light B with a central wavelength of 460±10nm and a wavelength range of 420 to 500nm. G-LED 20c generates green light G with a wavelength range of 480 to 600nm. R-LED 20d generates red light R with a central wavelength of 620 to 630nm and a wavelength range of 600 to 650nm.

[0058] The light source control unit 21 lights up the V-LED 20a, B-LED 20b, G-LED 20c, and R-LED 20d in either the normal observation mode or the special observation mode. Therefore, the light in which the colors of the four colors of light, namely, the purple light V, the blue light B, the green light G, and the red light R are mixed, is irradiated onto the observation object. Furthermore, in the normal observation mode, the light source control unit 21 controls each LED 20a to 20d in such a way that the light quantity ratio between the purple light V, the blue light B, the green light G, and the red light R becomes Vc:Bc:Gc:Rc. On the other hand, in the special observation mode, the light source control unit 21 controls each LED 20a to 20d in such a way that the light quantity ratio between the purple light V, the blue light B, the green light G, and the red light R becomes Vs:Bs:Gs:Rs.

[0059] In addition, in this specification, the light quantity ratio includes the case where the ratio of at least one semiconductor light source is 0 (zero). Therefore, it includes the case where any one or any two or more of the semiconductor light sources are not lit. For example, if the light quantity ratio between purple light V, blue light B, green light G, and red light R is 1:0:0:0, the case where only one semiconductor light source is lit and the other three are not lit is also considered to have a light quantity ratio.

[0060] like Figure 2 As shown, the light guide 41 is built into the endoscope 12 and the universal cord (cord connecting the endoscope 12 with the light source device 14 and the processor device 16), and transmits the light coupled by the optical path coupling unit 23 to the terminal end 12d of the endoscope 12. In addition, a multimode optical fiber can be used as the light guide 41. As an example, a thin optical cable with a core diameter of 105 μm, a cladding diameter of 125 μm, and a diameter of φ0.3 to 0.5 mm including a protective layer serving as an outer skin can be used.

[0061] An illumination optical system 30a and an imaging optical system 30b are provided at the distal end portion 12d of the endoscope 12. The illumination optical system 30a includes an illumination lens 45, and light from the light guide 41 is irradiated to the observation object via the illumination lens 45. The imaging optical system 30b includes an objective lens 46 and an imaging sensor 48. Reflected light from the observation object is incident on the imaging sensor 48 via the objective lens 46. As a result, a reflected image of the observation object is formed on the imaging sensor 48.

[0062] The image sensor 48 is a color image sensor that captures the reflected image of the subject and outputs an image signal. The image sensor 48 is preferably a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor. The image sensor 48 used in the present invention is a color image sensor for obtaining RGB image signals of three colors: R (red), G (green), and B (blue), that is, a so-called RGB image sensor having R pixels provided with R color filters, G pixels provided with G color filters, and B pixels provided with B color filters.

[0063] In addition, the image sensor 48 may be a so-called complementary color image sensor having complementary color filters of C (cyan), M (magenta), Y (yellow) and G (green) instead of an RGB color image sensor. When a complementary color image sensor is used, image signals of four colors, CMYG, are output, so it is necessary to convert the image signals of four colors, CMYG, into image signals of three colors, RGB, by complementary color-primary color conversion. Furthermore, the image sensor 48 may be a monochrome image sensor without a color filter. At this time, the light source control unit 21 needs to light up the blue light B, the green light G and the red light R in time periods, and implement synchronization processing in the processing of the image signal.

[0064] The image signal output from the image sensor 48 is sent 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 the analog signal, i.e., the image signal. The image signal that has passed through the CDS / AGC circuit 50 is converted into a digital image signal by an A / D (Analog / Digital) Converter) 52. The digital image signal that has undergone A / D conversion is input to the processor device 16.

[0065] The processor device 16 corresponds to a medical image processing device that processes medical images such as images obtained by the endoscope 12. The processor device 16 includes an image signal input unit 53, a DSP (Digital Signal Processor) 56, a noise removal unit 58, a signal switching unit 60, a normal image processing unit 62, a special image processing unit 64, and a video signal generation unit 66. The digital color image signal from the endoscope 12 is input to the image signal input unit 53. The color image signal is an RGB image signal composed of an R image signal (red signal) output from an R pixel of the imaging sensor 48, a G image signal (green signal) output from a G pixel of the imaging sensor 48, and a B image signal (blue signal) output from a B pixel of the imaging sensor 48.

[0066] DSP56 performs various signal processing such as defect correction processing, offset processing, gain correction processing, linear matrix processing, gamma conversion processing or demosaicing processing on the received image signal. In the defect correction processing, the signal of the defective pixel of the camera sensor 48 is corrected. In the offset processing, the dark current component is removed from the RGB image signal that has been subjected to the defect correction processing, and an accurate zero potential is set. In the gain correction processing, a specific gain is multiplied on the RGB image signal after the offset processing to adjust the signal level. The RGB image signal after the gain correction processing is subjected to linear matrix processing for improving color reproducibility. Thereafter, the brightness and chroma are adjusted by gamma conversion processing. De-mosaicing processing (also called isotropic processing, synchronous processing) is performed on the RGB image signal after the linear matrix processing, so that the signal of the insufficient color in each pixel is generated by interpolation. Through this demosaicing processing, all pixels have signals of various RGB colors.

[0067] The noise removal unit 58 removes noise from the RGB image signals by performing noise removal processing (such as a moving average method and a median filter method) on the RGB image signals subjected to gamma correction and the like by the DSP 56 . The RGB image signals from which noise has been removed are sent to the signal switching unit 60 .

[0068] The signal switching unit 60 sends the RGB image signal to the normal image processing unit 62 when the normal observation mode is set by the mode switching SW 13 a , and sends the RGB image signal to the special image processing unit 64 when the special observation mode is set.

[0069] The normal image processing unit 62 performs normal image processing on the RGB image signal. The normal image processing includes normal image structure enhancement processing, etc. The RGB image signal subjected to the normal image processing is input from the normal image processing unit 62 to the video signal generating unit 66 as a normal image.

[0070] The special image processing unit 64 generates a normal saturation emphasized image, a specific saturation emphasized image, or a normal image as a special image based on the RGB image signal. The special image processing unit 64 will be described in detail later. The special image generated by the special image processing unit 64 is input to the video signal generating unit 66.

[0071] The video signal generating unit 66 converts the normal image or special image input from the normal image processing unit 62 or the special image processing unit 64 into a video signal for displaying the image on the display 18. The display 18 displays the normal image or the special image based on the video signal.

[0072] like Figure 4As shown, the special image processing unit 64 includes an inverse gamma conversion unit 70, a Log conversion unit 71, a signal ratio calculation unit 72, a polar coordinate conversion unit 75, a saturation emphasis processing unit 76, a hue emphasis processing unit 77, an orthogonal coordinate conversion unit 78, an RGB conversion unit 79, a brightness adjustment unit 81, a structure emphasis unit 82, an inverse Log conversion unit 83 and a gamma conversion unit 84.

[0073] When the normal saturation emphasis mode is set by the special image processing section 64, the saturation emphasis processing section 76 performs normal saturation emphasis processing, and the hue emphasis processing section 77 performs normal hue emphasis processing, thereby generating a normal saturation emphasized image. When the special saturation emphasis mode is set, the saturation emphasis processing section 76 performs specific saturation emphasis processing, and the hue emphasis processing section 77 performs specific hue emphasis processing, thereby generating a specific saturation emphasized image. When the normal saturation mode is set, the saturation emphasis processing section 76 does not perform saturation emphasis processing, and the hue emphasis processing section 77 does not perform hue emphasis processing, thereby generating a normal saturation emphasized image.

[0074] The inverse gamma conversion unit 70 performs inverse gamma conversion on the input RGB3-channel digital image signal. The RGB image signal after the inverse gamma conversion is a reflectivity linear RGB signal that is linear with respect to the reflectivity reflected from the subject, so the proportion of the signal related to various biological information of the subject in the RGB image signal increases. In addition, the reflectivity linear R image signal is used as the 1R image signal, the reflectivity linear G image signal is used as the 1G image signal, and the reflectivity linear B image signal is used as the 1B image signal. These 1R image signal, 1G image signal and 1B image signal are collectively referred to as the 1RGB image signal.

[0075] The log conversion section 71 performs log conversion on the reflectivity linear RGB image signals, respectively. Thus, a log-converted R image signal (logR), a log-converted G image signal (logG), and a log-converted B image signal (logB) are obtained. The signal ratio calculation section 72 (corresponding to the "color information acquisition section" of the present invention) performs differential processing (logG-logB=logG / B=-log(B / G)) on the log-converted G image signal and the B image signal, thereby calculating the B / G ratio (the value with "-log" omitted in -log(B / G) is marked as "B / G ratio"). Furthermore, the G / R ratio is calculated by performing differential processing (logR-logG=logR / G=-log(G / R)) on the log-converted R image signal and the G image signal. The G / R ratio, like the B / G ratio, represents the value with "-log" omitted in -log(G / R).

[0076] In addition, the B / G ratio (first signal ratio) and G / R ratio (second signal ratio) of each pixel are calculated based on the pixel values ​​of the pixels located at the same position in the B image signal, the G image signal, and the R image signal. In addition, the B / G ratio and the G / R ratio of each pixel are calculated. In addition, the B / G ratio is correlated with the blood vessel depth (the distance from the mucosal surface to the location of a specific blood vessel), so if the blood vessel depth is different, the B / G ratio also changes. In addition, the G / R ratio is correlated with the blood volume (hemoglobin index), so if the blood volume changes, the G / R ratio also changes.

[0077] The polar coordinate conversion unit 75 converts the B / G ratio and the G / R ratio obtained by the signal ratio calculation unit 72 into a radius vector r and an angle θ. The polar coordinate conversion unit 75 converts all pixels into a radius vector r and an angle θ.

[0078] The chroma emphasis processing unit 76 performs chroma emphasis processing on a high chroma range located on the high chroma side relative to the chroma reference line and a low chroma range located on the low chroma side relative to the chroma reference line in a feature space formed by the B / G ratio and the G / R ratio of one of the plurality of color information. Specifically, the chroma emphasis processing unit 76 performs chroma emphasis processing to change the chroma difference between the plurality of observation object ranges contained in the observation object by expanding or compressing the radius vector r. The chroma emphasis processing performed by the chroma emphasis processing unit 76 includes a normal chroma emphasis processing and a specific chroma emphasis processing whose processing content is different from the normal chroma emphasis processing. The normal chroma emphasis processing is a processing to increase the chroma difference between the normal mucosa and the abnormal part. The specific chroma emphasis processing is a processing to give a change to the color of the low chroma area contained in the low chroma range while maintaining the hue of the normal mucosa, and to give a change to the color of the high chroma area contained in the high chroma range. In addition, the chroma reference line is preferably a line that intersects with the range in which the normal mucosa is distributed in the feature space. Furthermore, the switching between the normal saturation emphasis processing and the specific saturation emphasis processing is performed by the mode switching unit 13 a .

[0079] The hue emphasis processing section 77 performs hue emphasis processing for increasing the hue difference between the plurality of observation object ranges by expanding or compressing the angle θ. The hue emphasis processing performed by the hue emphasis processing section 77 includes normal hue emphasis processing and specific saturation emphasis processing whose processing content is different from that of the normal hue emphasis processing. The normal hue emphasis processing is processing for increasing the hue difference between the normal mucosa and the abnormal part. The specific hue emphasis processing is processing for changing the hue difference between the normal mucosa and the abnormal part, and the change in hue difference is different from that of the normal hue emphasis processing.

[0080] The radius vector r and the angle θ after the color saturation emphasis process and the hue emphasis process are converted into orthogonal coordinates by the orthogonal coordinate conversion section 78. Thus, they are converted into the B / G ratio and the G / R ratio after the angle expansion / compression process. The B / G ratio and the G / R ratio after the color saturation emphasis process and the hue emphasis process are converted into the second RGB image signal by the RGB conversion section 79 using at least one image signal among the first RGB image signals. For example, the RGB conversion section 79 performs calculations based on the 1G image signal and the B / G ratio among the first RGB image signals, thereby converting the B / G ratio into the second B image signal. Furthermore, the RGB conversion section 79 performs calculations based on the 1G image signal and the G / R ratio among the first RGB image signals, thereby converting the G / R ratio into the second R image signal. Furthermore, the RGB conversion section 79 outputs the 1G image signal as the second G image signal without performing any special conversion on the 1G image signal. These second R image signal, second G image signal, and second B image signal are collectively referred to as the second RGB image signal.

[0081] The brightness adjustment unit 81 uses the first RGB image signal and the second RGB image signal to adjust the pixel value of the second RGB image signal. The reason why the pixel value of the second RGB image signal is adjusted by the brightness adjustment unit 81 is as follows. The brightness of the second RGB image signal obtained by the color region expansion / compression processing by the saturation emphasis processing unit 76 and the hue emphasis processing unit 77 may be greatly changed compared with the brightness of the first RGB image signal. Therefore, the pixel value of the second RGB image signal is adjusted by the brightness adjustment unit 81 so that the brightness of the second RGB image signal after the brightness adjustment is the same as that of the first RGB image signal.

[0082] The brightness adjustment unit 81 includes: a first brightness information calculation unit 81a for obtaining first brightness information Yin based on the first RGB image signal; and a second brightness information calculation unit 81b for obtaining second brightness information Yout based on the second RGB image signal. The first brightness information calculation unit 81a calculates the first brightness information Yin according to the calculation formula "kr×pixel value of the first R image signal+kg×pixel value of the first G image signal+kb×pixel value of the first B image signal". The second brightness information calculation unit 81b also calculates the second brightness information Yout according to the same calculation formula as the first brightness information calculation unit 81a. If the first brightness information Yin and the second brightness information Yout are obtained, the brightness adjustment unit 81 adjusts the pixel value of the second RGB image signal by performing calculations according to the following formulas (E1) to (E3).

[0083] (E1): R * =Pixel value of the 2nd R image signal × Yin / Yout

[0084] (E2): G *=Pixel value of the 2G image signal × Yin / Yout

[0085] (E3): B * =Pixel value of the 2B image signal × Yin / Yout

[0086] In addition, "R*" represents the 2nd R image signal after brightness adjustment, "G*" represents the 2nd G image signal after brightness adjustment, and "B*" represents the 2nd B image signal after brightness adjustment. Furthermore, "kr", "kg" and "kb" are arbitrary constants in the range of "0" to "1".

[0087] The structure emphasis section 82 performs structure emphasis processing on the second RGB image signal processed by the RGB conversion section 79. As the structure emphasis processing, frequency filtering or the like is used. The inverse Log conversion section 83 performs inverse Log conversion on the second RGB image signal processed by the structure emphasis section 82. Thus, a second RGB image signal having a true pixel value can be obtained. The gamma conversion section 84 performs gamma conversion on the RGB image signal processed by the inverse Log conversion section 83. Thus, a second RGB image signal having a grayscale suitable for an output device such as a display 18 can be obtained. The second RGB image signal processed by the gamma conversion section 84 is sent to the video signal generation section 66.

[0088] like Figure 5 As shown, the saturation emphasis processing unit 76 and the hue emphasis processing unit 77 increase the saturation difference or hue difference among the plurality of observation object ranges included in the observation object, including the first range of normal mucosa, the second range of atrophic mucosa, the third range of deep blood vessels under the atrophic mucosa (hereinafter referred to as deep blood vessels), the fourth range of BA (Brownish Area), and the fifth range of redness. In the first quadrant of the signal ratio space (feature space) formed by the B / G ratio and the G / R ratio, the first range of normal mucosa is roughly distributed in the center. The second range of atrophic mucosa is slightly located on the clockwise side (negative side described later) relative to the baseline SL passing through the first range of normal mucosa, and is distributed at a position closer to the origin than the first range of normal mucosa. The third range of deep blood vessels is distributed on the clockwise side (negative side described later) relative to the baseline SL. The fourth range of BA is distributed on the slightly counterclockwise side (positive side described later) relative to the baseline SL. The fifth range of redness is distributed on the clockwise side (negative side described later) relative to the reference line SL. The fourth range of BA and the fifth range of redness are located farther from the origin than the first range of normal mucosa. In addition, it is preferred that the normal mucosa is included in the normal part of the observation object, and the atrophic mucosa, deep blood vessels, BA and redness are included in the abnormal part of the observation object. In addition, the reference line SL corresponds to the hue reference line SLh described later.

[0089] like Figure 6 As shown, the radius r represented by the coordinates in the radius vector change range Rm in the signal ratio space is changed by the saturation emphasis processing unit 76, while the radius r is not changed for the coordinates outside the radius vector change range Rx. With respect to the radius vector change range Rm, the radius r is within the range of "r1" to "r2" (r1<r2). Furthermore, within the radius vector change range Rm, a saturation reference line SLs is set on the radius vector rc between the radius vector r1 and the radius vector r2. Here, the larger the radius vector r, the higher the saturation, so the range rccr1 (r1<r<rc) in which the radius vector r is smaller than the radius vector rc represented by the saturation reference line SLs becomes a low saturation range. On the other hand, the range rccr2 (re<r<r2) in which the radius vector r is larger than the radius vector rc represented by the saturation reference line SLs becomes a high saturation range.

[0090] like Figure 7 As shown, the normal chroma emphasis process outputs the radius vector Rx(r) relative to the input of the radius vector r of the coordinates included in the radius vector change range Rm. The input / output relationship performed by the normal chroma emphasis process is represented by a solid line. In the normal chroma emphasis process, an S-shaped conversion curve is used to set the output value Rx(r) to be smaller than the input value r in the low chroma range rcrl, and on the other hand, the output value Rx(r) is set to be larger than the input value r in the high chroma range rer2. In addition, the slope Kx in Rx(rc) is set to be greater than "1". As a result, the chroma of the observed object included in the low chroma range can be further reduced, and on the other hand, the chroma of the observed object included in the high chroma range can be further increased. Through this chroma emphasis, the chroma difference between multiple observation object ranges can be increased.

[0091] like Figure 8 As shown, the specific chroma emphasis process outputs the radius vector Ry(r) relative to the input of the radius vector r of the coordinates included in the radius vector change range Rm. The input / output relationship performed by the specific chroma emphasis process is represented by a solid line. In the specific chroma emphasis process, an inverse S-shaped conversion curve is used to set the output value Ry(r) to be larger than the input value r in the low chroma range rcr1, and on the other hand, the output value Ry(r) is set to be smaller than the input value r in the high chroma range rcr2. In addition, the slope Ky in Ry(rc) is set to be less than "1".

[0092] Thus, the observation object included in the low chroma range can be made high-saturated, and the observation object included in the high chroma range can be made low-saturated. When performing the normal chroma emphasis process, the difference from the color of the normal mucosa can be increased, and the color of the low chroma area and the high chroma area can be changed. In contrast, when performing the specific chroma emphasis process, the low chroma area that is difficult to change the color in the normal chroma emphasis process is made high-saturated and the high chroma area is made low-saturated, so that the low chroma area and the high chroma area can be given a color change.

[0093] like Fig. 9 As shown, the angle θ represented by the coordinates located in the angle change range Rn in the signal ratio space is changed by the hue emphasis processing unit 77, while the angle θ of the coordinates outside the angle change range Rn is not changed. The angle change range Rn is composed of the range of angle θ1 in the counterclockwise direction (first hue direction) from the hue reference line SLh and the range of angle θ2 in the clockwise direction (second hue direction) from the hue reference line SLh. The angle θ of the coordinates included in the angle change range Rn is redefined by the angle θ formed with the hue reference line SLh, and the counterclockwise side relative to the hue reference line SLh is defined as the positive side, and the clockwise side relative to the hue reference line SLh is defined as the negative side. If the angle θ changes, the hue also changes, so the range of angle θ1 in the angle change range Rn is defined as the positive side hue range θ1, and the range of angle θ2 is defined as the negative side hue range θ2. In addition, the hue reference line SLh is preferably a line that intersects with the range of normal mucosa in the feature space, similar to the chroma reference line SLs.

[0094] like Fig.10 As shown, the normal hue emphasis processing outputs an angle Fx(θ) relative to the input of the angle θ of the coordinates included in the angle change range Rn. The input / output relationship performed by the normal hue emphasis processing is represented by a solid line. In the normal hue emphasis processing, the output Fx(θ) is set to be smaller than the input θ within the hue range θ2 on the negative side, and on the other hand, the output Fx(θ) is set to be larger than the input θ within the hue range θ1 on the positive side. Thereby, the hue difference between the observation object included in the hue range on the negative side and the observation object included in the hue range on the positive side can be increased. Through this hue emphasis, the hue difference between multiple observation object ranges can be increased.

[0095] like Fig.11As shown, the specific hue emphasis processing outputs an angle Fx(θ) relative to the input of the angle θ of the coordinates included in the angle change range Rn. The input / output relationship performed by the specific hue emphasis processing is represented by a solid line. In the specific hue emphasis processing, the output Fx(θ) is set to be larger than the input θ in the hue range θ2 on the negative side, and on the other hand, the output Fx(θ) is set to be smaller than the input θ in the hue range θ1 on the positive side. As a result, the hue difference between the observation object included in the hue range on the negative side and the observation object included in the hue range on the positive side is reduced.

[0096] The following describes the positional relationship between the low saturation area and the high saturation area before and after the normal saturation emphasis process and before and after the specific saturation emphasis process. Fig.12 As shown in FIG. 1 , the low saturation region (solid line) after the normal saturation emphasis process moves away from the saturation baseline SLs compared to the low saturation region (dashed line) before the normal saturation emphasis process. The closer to the origin in the feature space, the lower the saturation, so the low saturation region is low-saturated by the normal saturation emphasis process. In contrast, the high saturation region (solid line) after the normal saturation emphasis process moves away from the saturation baseline SLs compared to the high saturation region (dashed line) before the normal saturation emphasis process. The farther away from the origin in the feature space, the higher the saturation, so the high saturation region is high-saturated by the normal saturation emphasis process.

[0097] In contrast, Fig.13 As shown in FIG. 1 , the low saturation region (solid line) after the specific saturation emphasis processing moves closer to the saturation reference line SLs than the low saturation region (dashed line) before the specific saturation emphasis processing. Therefore, the low saturation region is made high-saturated by the specific saturation emphasis processing. On the other hand, the high saturation region (solid line) after the specific saturation emphasis processing moves closer to the saturation reference line SLs than the high saturation region (dashed line) before the specific saturation emphasis processing. Therefore, the high saturation region is made low-saturated by the specific saturation emphasis processing.

[0098] Here, the references cited as references Figures 1 to 3 , for the original image with low saturation area without any processing of normal saturation emphasis processing or special saturation emphasis processing (reference Figure 1 ), the usual saturation-emphasized image in low-saturation areas (reference Figure 2 ) and specific saturation-enhanced images in low-saturation areas (reference Figure 3) for comparison. The chroma of the normal chroma emphasized image in the low chroma area becomes lower than that of the original image in the low chroma area. Furthermore, it can be seen that the normal chroma emphasized image in the low chroma area has a larger change in the color of the middle chroma than the original image in the low chroma area, while the change in the color of the low chroma is less. In contrast, the chroma of the specific chroma emphasized image in the low chroma area becomes higher than that of the original image in the low chroma area. Furthermore, it can be seen that the specific chroma emphasized image in the low chroma area has a smaller change in the color of the middle chroma than the original image in the low chroma area, but the change in the color of the low chroma is increased.

[0099] Also, use the references provided as references Figures 4 to 6 , for the original image with high saturation area without any processing of normal saturation emphasis processing or special saturation emphasis processing (reference Figure 4 ), the usual saturation-emphasized image in high saturation areas (reference Figure 5 ) and specific saturation-enhanced images in high-saturation areas (reference Figure 6 ). The chroma of the normal chroma emphasized image in the high chroma area is higher than that of the original image in the high chroma area. Furthermore, it can be seen that the normal chroma emphasized image in the high chroma area has a larger change in the color of the middle chroma than the original image in the high chroma area, while the change in the color of the high chroma is less. In contrast, the chroma of the specific chroma emphasized image in the high chroma area is lower than that of the original image in the high chroma area. Furthermore, it can be seen that the specific chroma emphasized image in the high chroma area has a smaller change in the color of the middle chroma than the original image in the high chroma area, but the change in the color of the high chroma is greater.

[0100] in addition, Fig.14 The positional relationship between the 1st to 5th ranges before and after the normal saturation emphasis treatment and the normal hue emphasis treatment is shown in the figure. The difference between the 2nd range of the atrophic mucosa (atrophic mucosa 1) after the normal saturation emphasis treatment and the normal hue emphasis treatment and the 1st range of the normal mucosa increases compared with the 2nd range of the atrophic mucosa (dashed line) before the normal saturation emphasis treatment and the normal hue emphasis treatment. Similarly, the deep blood vessels (deep blood vessels 1), the 4th range of BA (BA), and the 5th range of redness (redness 1) after the normal saturation emphasis treatment and the normal hue emphasis treatment increase compared with the deep blood vessels (dashed line), the 4th range of RA (dashed line), and the 5th range of redness (dashed line) before the normal saturation emphasis treatment and the normal hue emphasis treatment.

[0101] In addition, a is obtained by Lab converting the first RGB image signal by the Lab conversion unit. * , b * (Element a representing color information, i.e., hue in CIE Lab space * , b* . The same below) forms a feature space (ab space), such as Fig.15 As shown in FIG. 1 , by performing the normal saturation emphasis processing, the low saturation area moves toward the direction of low saturation as in the case of the signal ratio space, while the high saturation area moves toward the direction of high saturation as in the case of the signal ratio space. Fig.16 As shown, by performing the specific saturation emphasis processing, the low saturation area moves toward the high saturation direction as in the case of the signal ratio space, while the high saturation area moves toward the low saturation direction as in the case of the signal ratio space.

[0102] Next, according to Fig.17 The flowchart of the special observation mode is explained. The mode switch SW13a is operated to switch to the normal chroma emphasis mode in the special observation mode. If the normal chroma emphasis mode is switched, the normal chroma emphasis processing is performed in the chroma emphasis processing unit 76 of the processor device 16. If a specific input value is input to the chroma emphasis processing unit 76, the normal chroma emphasis processing is performed on the specific input value and the output value is output. The output value included in the low chroma range after the normal chroma emphasis processing is smaller than the input value included in the low chroma range before the normal chroma emphasis processing. The output value included in the high chroma range after the normal chroma emphasis processing is larger than the input value included in the high chroma range before the normal chroma emphasis processing. A normal chroma emphasized image is generated by performing the above normal chroma emphasis processing and displayed on the display 18. In the normal chroma emphasized image, the color change of the intermediate chroma is emphasized, and the chroma difference and hue difference with the normal part are emphasized.

[0103] On the other hand, in a normal chroma emphasized image, it is difficult to impart a change to the color in the low chroma region or the high chroma region. Therefore, when it is desired to grasp the change in the color of these low chroma regions or the high chroma regions, the mode switch SW13a is operated to switch to the specific chroma emphasized mode. When the specific chroma emphasized mode is switched, the chroma emphasized processing section 76 of the processor device 16 performs a specific chroma emphasized processing. When a specific input value is input to the chroma emphasized processing section 76, the specific chroma emphasized processing is performed on the specific input value and an output value is output. The output value included in the low chroma range after the specific chroma emphasized processing is larger than the input value included in the low chroma range before the specific chroma emphasized processing. The output value included in the high chroma range after the specific chroma emphasized processing is smaller than the input value included in the high chroma range before the specific chroma emphasized processing. By performing the above specific chroma emphasized processing, a specific chroma emphasized image is generated and displayed on the display 18. In the specific chroma emphasized image, the emphasis of the change in the color of the intermediate chroma is suppressed, while the change in the color in the low chroma region and the high chroma region is emphasized. When the diagnosis of the observation object based on the special observation mode such as the normal saturation-emphasized image or the specific saturation-emphasized image is completed, the mode switching SW 13 a is operated to return to the normal observation mode.

[0104] In the above-described embodiment, the mode switch SW13a is used to manually switch between the normal saturation emphasis processing and the specific saturation emphasis processing. However, the normal saturation emphasis processing and the specific saturation emphasis processing may be automatically switched using an index value obtained based on a color image signal. In this case, when the index value satisfies the first condition indicating low saturation or high saturation, the specific saturation emphasis processing is switched to, and when the index value satisfies the second condition indicating intermediate saturation, the normal saturation emphasis processing is switched to. For example, when a representative value (e.g., average value) of the B / G ratio and a representative value (e.g., average value) of the G / R ratio are used as index values, as shown in FIG. Fig.18 As shown, the chroma emphasis processing switching unit 85 receives the B / G ratio and the G / R ratio, and automatically switches between the normal chroma emphasis processing and the specific chroma emphasis processing according to the received representative values ​​of the B / G ratio and the G / R ratio.

[0105] At this time, if Fig.19 As shown, the first condition related to low saturation or high saturation preferably has the representative value of the B / G ratio and the representative value of the G / R ratio fall in the regions RL and RH of the feature space, and the second condition related to intermediate saturation preferably falls in the region RM of the feature space. The saturation emphasis processing switching unit 85 switches to the specific saturation emphasis processing when the representative value of the B / G ratio and the representative value of the G / R ratio fall in the regions RL and RH. On the other hand, the saturation emphasis processing switching unit 85 switches to the normal saturation emphasis processing when the representative value of the B / G ratio and the representative value of the G / R ratio fall in the region RM.

[0106] Furthermore, in the above-mentioned embodiment, the chroma reference line SLs used in the chroma emphasis processing section 76 is fixed, and in the chroma emphasis processing section 76, the chroma reference line SLs may be shifted according to the mucosal color obtained from the color image signal. After the chroma reference line SLs is shifted, chroma emphasis processing based on the shifted chroma reference line SLs is performed. Specifically, in the case where the chroma reference line SLs is determined based on the color of the normal mucosa, the chroma emphasis processing section 76 calculates the color of the normal mucosa as the mucosal color obtained from the color image signal. If the deviation amount between the calculated color of the normal mucosa and the reference color is within the allowable range, the chroma reference line SLs is not shifted. On the other hand, when the deviation amount exceeds the allowable range, the chroma reference line SLs is shifted according to the calculated color of the normal mucosa.

[0107] For example, Fig. 20 As shown, when the range of the normal mucosa in the feature space is slightly offset to the right compared to the range of the reference normal mucosa, the saturation reference line SLs is shifted according to the deviation amount between the average color of the normal mucosa and the average color of the reference normal mucosa.

[0108] In addition, in the above-mentioned embodiment, the B / G ratio and the G / R ratio are calculated based on the first RGB image signal by the signal ratio calculation unit 72, and the saturation emphasis processing and the hue emphasis processing are performed in the signal ratio space formed by these B / G ratios and G / R ratios, but color information different from the B / G ratio and the G / R ratio can also be calculated, and the saturation emphasis processing and the hue emphasis processing can be performed in the feature space formed by the color information.

[0109] For example, color difference signals Cr and Cb may be obtained as color information, and saturation emphasis processing and hue emphasis processing may be performed in a feature space formed by the color difference signals Cr and Cb. Fig.21 The special image processing unit 92 shown in FIG. 6 is different from the special image processing unit 64 in that the special image processing unit 92 does not include the Log conversion unit 71, the signal ratio calculation unit 72, and the inverse Log conversion unit 83. Instead, the special image processing unit 92 includes a brightness and color difference signal conversion unit 86. In other structures, the special image processing unit 92 is the same as the special image processing unit 64.

[0110] The brightness color difference signal conversion section 86 (corresponding to the "color information acquisition section" of the present invention) converts the first RGB image signal into a brightness signal Y and color difference signals Cr and Cb. A well-known conversion formula is used for the conversion into the color difference signals Cr and Cb. The color difference signals Cr and Cb are sent to the polar coordinate conversion section 75. The brightness signal Y is sent to the RGB conversion section 79 and the brightness adjustment section 81. The color difference signals Cr and Cb and the brightness signal Y processed by the orthogonal coordinate conversion section 78 are converted into a second RGB image signal by the RGB conversion section 79. The pixel value of the second RGB image signal is adjusted by the brightness adjustment section 81 using the brightness signal Y as the first brightness information Yin and the second brightness information obtained by the second brightness information calculation section 81b as the second brightness information Yout. In addition, the calculation method of the second brightness information Yout and the adjustment method of the pixel value of the second RGB image signal are the same as those of the above-mentioned special image processing section 64.

[0111] Then, similarly to the case of the signal ratio space, the normal saturation emphasis processing and the normal hue emphasis processing or the specific saturation emphasis processing and the normal hue emphasis processing are performed by changing the radius r and the angle θ in the CrCb space, which is a feature space composed of the color difference signals Cr and Cb. Fig. 22 As shown, in the CrCb space, the low chroma region (solid line) after the normal chroma emphasis process moves away from the chroma baseline SLs compared to the low chroma region (dashed line) before the normal chroma emphasis process. In the CrCb space, the closer to the origin, the lower the chroma, so the low chroma region is low-saturated by the normal chroma emphasis process. In contrast, the high chroma region (solid line) after the normal chroma emphasis process moves away from the chroma baseline SLs compared to the high chroma region (dashed line) before the normal chroma emphasis process. In the CrCb space, the farther away from the origin, the higher the chroma, so the high chroma region is high-saturated by the normal chroma emphasis process.

[0112] In contrast, Fig.23 As shown in FIG. 1 , the low saturation region (solid line) after the specific saturation emphasis processing moves closer to the saturation reference line SLs than the low saturation region (dashed line) before the specific saturation emphasis processing. Therefore, the low saturation region is made high-saturated by the specific saturation emphasis processing. On the other hand, the high saturation region (solid line) after the specific saturation emphasis processing moves closer to the saturation reference line SLs than the high saturation region (dashed line) before the specific saturation emphasis processing. Therefore, the high saturation region is made low-saturated by the specific saturation emphasis processing.

[0113] Furthermore, hue H (Hue) and saturation S (Saturation) can be obtained as color information, and saturation emphasis processing and hue emphasis processing can be performed in the HS space formed by hue H and saturation S. When using hue H and saturation S, use Fig.24 The special image processing unit 96 shown in FIG. 1 is different from the special image processing unit 64 in that the special image processing unit 96 does not include the Log conversion unit 71, the signal ratio calculation unit 72, the polar coordinate conversion unit 75, the orthogonal coordinate conversion unit 78, and the inverse Log conversion unit 83. Instead, the special image processing unit 96 includes an HSV conversion unit 87. In other structures, the special image processing unit 96 is the same as the special image processing unit 64.

[0114] The HSV conversion unit 87 (corresponding to the "color information acquisition unit" of the present invention) converts the first RGB image signal into hue H, chroma S and brightness V (Value). A well-known conversion formula is used for the conversion into hue H, chroma S and brightness V. The hue H and chroma S are sent to the parallel shift unit 90. The brightness V is sent to the RGB conversion unit 79. The hue H, chroma S and brightness V processed by the parallel shift unit 90 are converted into a second RGB image signal by the RGB conversion unit 79. The pixel value of the second RGB image signal is adjusted by the brightness adjustment unit 81 using the first brightness information Yin calculated by the first brightness information calculation unit 81a and the second brightness information Yout calculated by the second brightness information calculation unit 81b. In addition, the calculation method of the first brightness information Yin and the second brightness information Yout and the adjustment method of the pixel value of the second RGB image signal are the same as those of the above-mentioned special image processing unit 64.

[0115] The normal saturation emphasis processing, normal hue emphasis processing, and specific saturation emphasis processing in the HS space formed by hue H and chroma S do not expand or compress the radius r and angle θ as in the signal ratio space and CrCb space, but perform processing to move each pixel in parallel. By performing the normal saturation emphasis processing and the normal hue emphasis processing in the HS space, in the HS space, Fig.25 As shown in FIG. 1 , the low saturation area (solid line) after the normal saturation emphasis process is moved in the direction away from the saturation baseline SLs compared to the low saturation area (dashed line) before the normal saturation emphasis process. The saturation S is represented by the vertical axis, so the low saturation area is low-saturated by the normal saturation emphasis process. On the other hand, the high saturation area (solid line) after the normal saturation emphasis process is moved in the direction away from the saturation baseline SLs compared to the high saturation area (dashed line) before the normal saturation emphasis process. Therefore, the high saturation area is high-saturated by the normal saturation emphasis process.

[0116] In contrast, Fig.26As shown in FIG. 1 , the low saturation area (solid line) after the specific saturation emphasis processing is moved closer to the saturation baseline SLs than the low saturation area (dashed line) before the specific saturation emphasis processing. Therefore, the low saturation area is made high saturated by the specific saturation emphasis processing. On the other hand, the high saturation area (solid line) after the specific saturation emphasis processing is moved closer to the saturation baseline SLs than the high saturation area (dashed line) before the specific saturation emphasis processing. Therefore, the high saturation area is made low saturated by the specific saturation emphasis processing.

[0117] [Second embodiment]

[0118] In the second embodiment, the observation object is illuminated by using a laser light source and a fluorescent substance instead of the four-color LEDs 20 a to 20 d shown in the first embodiment. The rest is the same as the first embodiment.

[0119] like Fig. 27 As shown, in the endoscope system 100 of the second embodiment, a blue laser light source ( ) emitting blue laser light with a central wavelength of 445±10 nm is provided in the light source device 14 instead of the four colors of LEDs 20a to 20d. Fig. 27 104 and a blue-violet laser light source (marked as "445LD" in FIG. 104) that emits a blue-violet laser with a central wavelength of 405±10nm Fig. 27 The light emitted from the semiconductor light emitting elements of the light sources 104 and 106 is individually controlled by the light source control unit 108, and the light intensity ratio of the emitted light of the blue laser light source 104 and the emitted light of the blue-violet laser light source 106 can be changed freely.

[0120] In the normal observation mode, the light source control unit 108 drives the blue laser light source 104. In contrast, in the special observation mode, the blue laser light source 104 and the blue-violet laser light source 106 are driven and controlled so that the emission ratio of the blue laser light is greater than the emission ratio of the blue-violet laser light. The laser light emitted from the above light sources 104 and 106 is incident on the light guide 41 via optical components such as a focusing lens, an optical fiber or a combiner (none of which are shown in the figure).

[0121] In addition, it is preferred that the half width of the blue laser or the blue-violet laser be set to about ±10 nm. In addition, the blue laser light source 104 and the blue-violet laser light source 106 can use a large-area InGaN laser diode, and can also use an InGaNAs laser diode or a GaNAs laser diode. In addition, as the above-mentioned light source, a structure using a light-emitting diode or other light-emitting body can also be adopted.

[0122] In addition to the illumination lens 45, the illumination optical system 30a is provided with a fluorescent body 110 into which the blue laser light or the blue-violet laser light from the light guide 41 is incident. The blue laser light is irradiated to the fluorescent body 110, whereby fluorescence is emitted from the fluorescent body 110. In addition, a part of the blue laser light directly passes through the fluorescent body 110. The blue-violet laser light passes through the fluorescent body 110 without exciting it. The light emitted from the fluorescent body 110 is irradiated into the subject via the illumination lens 45.

[0123] Here, in the normal observation mode, mainly the blue laser is incident on the phosphor 110, so Fig.28 As shown in FIG. 1 , a white light obtained by combining blue laser light and fluorescent light emitted from the fluorescent body 110 by the blue laser light is irradiated onto the observation object. On the other hand, in the special observation mode, two laser beams, the blue laser light and the blue laser light, are incident on the fluorescent body 110, so that Fig.29 As shown, special light obtained by combining blue-violet laser light, blue laser light, and fluorescent light emitted from the fluorescent body 110 excited by the blue laser light is irradiated into the subject.

[0124] In addition, the phosphor 110 preferably includes a plurality of phosphors (for example, YAG-based phosphors or BAM (BaMgAl 10 O 17 As in this structural example, as long as the semiconductor light-emitting element is used as the excitation light source of the phosphor 110, high-luminous efficiency and high-intensity white light can be obtained, and not only the intensity of the white light can be easily adjusted, but also the changes in the color temperature and chromaticity of the white light can be suppressed to a very small extent.

[0125] [Third embodiment]

[0126] In the third embodiment, instead of the four colors of LEDs 20a to 20d shown in the first embodiment, a broadband light source such as a xenon lamp and a rotating filter are used to illuminate the observation object. In addition, a monochrome imaging sensor is used instead of the color imaging sensor 48 to capture the observation object. Other aspects are the same as the first embodiment.

[0127] like Fig.30 As shown, in the endoscope system 200 of the third embodiment, a broadband light source 202, a rotating filter 204, and a filter switching unit 205 are provided in place of the four-color LEDs 20a to 20d in the light source device 14. In addition, a monochrome imaging sensor 206 without a color filter is provided in place of the color imaging sensor 48 in the imaging optical system 30b.

[0128] The broadband light source 202 is a xenon lamp, a white LED, etc., which emits white light in a wavelength range from blue to red. The rotating filter 204 includes a normal observation mode filter 208 disposed inside and a special observation mode filter 209 disposed outside (see Fig.31 ). The filter switching unit 205 moves the rotary filter 204 in the radial direction, and when the normal observation mode is set by the mode switching SW13a, the normal observation mode filter 208 of the rotary filter 204 is inserted into the optical path of the white light, and when the special observation mode is set, the special observation mode filter 209 of the rotary filter 204 is inserted into the optical path of the white light.

[0129] like Fig.31 As shown in FIG. 1 , a B filter 208a that transmits blue light in white light, a G filter 208b that transmits green light in white light, and an R filter 208c that transmits red light in white light are arranged along the circumferential direction on the normal observation mode filter 208. Therefore, in the normal observation mode, the rotating filter 204 rotates, and the blue light, green light, and red light are alternately irradiated to the observation object.

[0130] A Bn filter 209a that transmits blue narrowband light of a specific wavelength in white light, a G filter 209b that transmits green light in white light, and an R filter 209c that transmits red light in white light are arranged along the circumferential direction on the special observation mode filter 209. Therefore, in the special observation mode, the rotating filter 204 rotates, and the blue narrowband light, green light, and red light are alternately irradiated to the observation object.

[0131] In the endoscope system 200, in the normal observation mode, whenever the blue light, green light, and red light are irradiated to the observation object, the inside of the subject is photographed by the monochrome imaging sensor 206. Thus, image signals of three colors, RGB, can be obtained. Then, based on these RGB image signals, a normal image is generated by the same method as in the first embodiment described above.

[0132] On the other hand, in the special observation mode, whenever the blue narrowband light, green light, and red light are irradiated to the observation object, the inside of the subject is photographed by the monochrome imaging sensor 206. Thus, a Bn image signal, a G image signal, and an R image signal can be obtained. A special image is generated based on these Bn image signals, G image signals, and R image signals. When generating a special image, the Bn image signal is used instead of the B image signal. The other special images are generated in the same manner as in the first embodiment.

[0133] [Fourth embodiment]

[0134] In the fourth embodiment, a swallowable capsule endoscope is used instead of the insertion-type endoscope 12 and the light source device 14 to acquire RGB image signals required for generating a normal image or a special image.

[0135] like Fig.32 As shown, the capsule endoscope system 300 of the fourth embodiment includes a capsule endoscope 302, a transceiver antenna 304, a capsule receiving device 306, a processor device 16, and a display 18. The capsule endoscope 302 includes an LED 302a, an imaging sensor 302b, an image processing unit 302c, and a transmitting antenna 302d. In addition, the processor device 16 is the same as the first embodiment, but in the fourth embodiment, a mode switching SW 308 for switching between a normal observation mode and a special observation mode is newly provided.

[0136] LED 302a emits white light, and a plurality of LEDs are provided in the capsule endoscope 302. Here, as LED 302a, a white LED having a blue light source and a fluorescent body that converts the wavelength of light from the blue light source to emit fluorescence is preferably used. LD (Laser Diode) may also be used instead of LED. The white light emitted from LED 302a illuminates the observation object.

[0137] The image sensor 302b is a color image sensor that captures an observation object illuminated by white light and outputs an RGB image signal. Here, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor is preferably used as the image sensor 302b. The RGB image signal output from the image sensor 302b is processed by the image processing unit 302c to be a signal that can be transmitted by the transmitting antenna 302d. The RGB image signal processed by the image processing unit 302c is wirelessly transmitted from the transmitting antenna 302d to the transmitting and receiving antenna 304.

[0138] The transceiver antenna 304 is attached to the subject's body and receives the RGB image signal from the transmitting antenna 302d. The transceiver antenna 304 wirelessly transmits the received RGB image signal to the capsule receiving device 306. The capsule receiving device 306 is connected to the image signal input unit 53 of the processor device 16 and transmits the RGB image signal from the transceiver antenna 304 to the image signal input unit 53.

[0139] In addition, in the above-mentioned embodiment, the Figure 3 The luminous spectrum shown is 4 colors of light, but the luminous spectrum is not limited to this. Fig.33As shown, the green light G and the red light R can also have Figure 3 The same spectrum, on the other hand, the purple light Vs is set to have a central wavelength of 410 to 420 nm and Figure 3 The blue light Bs may be light having a wavelength range slightly longer than the purple light V. In addition, the blue light Bs may be light having a wavelength range slightly longer than the purple light V. Figure 3 The blue light B is light having a wavelength range slightly on the shorter wavelength side.

[0140] In the first embodiment, the B / G ratio and the G / R ratio are converted into the radial vector r and the deflection angle θ by polar coordinate conversion, and the color emphasis processing and the hue emphasis processing of the expansion or compression angle are performed according to the converted radial vector r and the deflection angle θ, and then the B / G ratio and the G / R ratio are restored again. However, it is also possible to Fig.34 As shown, a two-dimensional LUT (Look Up Table) 400 is used to directly convert the B / G ratio and G / R ratio into the first or second processed B / G ratio and G / R ratio without performing polar coordinate conversion or the like according to the B / G ratio and G / R ratio.

[0141] In addition, the B / G ratio and the G / R ratio are associated with the B / G ratio and the G / R ratio obtained by performing color emphasis processing and hue emphasis processing based on the B / G ratio and the G / R ratio and are stored in the two-dimensional LUT400. Here, when the normal saturation emphasis mode is set, the correspondence between the B / G ratio and the G / R ratio and the B / G ratio and the G / R ratio obtained by the normal saturation emphasis processing and the normal hue emphasis processing is used. When the specific saturation emphasis mode is set, the correspondence between the B / G ratio and the G / R ratio and the B / G ratio and the G / R ratio obtained by the normal saturation emphasis processing and the specific hue emphasis processing is used. In addition, the first RGB image signal output from the inverse gamma conversion unit 70 is input to the two-dimensional LUT400 and the RGB conversion unit 79.

[0142] In the above-mentioned embodiment, the hardware structure of the processing unit (processing unit) included in the processor device 16 such as the image signal input unit 53, the noise removal unit 58, the signal switching unit 60, the normal image processing unit 62, the special image processing unit 64, the special image processing unit 92, the special image processing unit 96, the video signal generating unit 66, the inverse gamma conversion unit 70, the Log conversion unit 71, the signal ratio calculation unit 72, the polar coordinate conversion unit 75, the saturation emphasis processing unit 76, the hue emphasis processing unit 77, the orthogonal coordinate conversion unit 78, the RGB conversion unit 79, the brightness adjustment unit 81, the structure emphasis unit 82, the inverse Log conversion unit 83, the gamma conversion unit 84, the saturation emphasis processing switching unit 85, the brightness and color difference signal conversion unit 86, and the HSV conversion unit 87 is the following various processors (processors). Various processors include general-purpose processors such as CPUs (Central Processing Units) that perform various processing unit functions by executing software (programs), processors such as FPGAs (Field Programmable Gate Arrays) whose circuit structures can be changed after manufacturing, namely programmable logic devices (PLDs), and processors with circuit structures specially designed for performing various processes, namely dedicated circuits.

[0143] One processing unit may be composed of one of these various processors, or may be composed of a combination of two or more processors of the same or different types (for example, a combination of multiple FPGAs or a combination of a CPU and an FPGA). Furthermore, multiple processing units may be composed of one processor. As an example of multiple processing units composed of one processor, the first type is a form in which one processor is composed of one or more CPUs and software, such as represented by computers such as clients or servers, and the processor performs the functions of multiple processing units. The second type is a form of a processor represented by a system on chip (SoC) that uses one IC (Integrated Circuit) chip to realize the functions of the entire system including multiple processing units. In this way, various processing units are composed of one or more of the above-mentioned various processors as a hardware structure.

[0144] The hardware structure of these various processors is more specifically a circuit in the form of a combination of circuit elements such as semiconductor elements. Also, the hardware structure of the storage unit is a storage device such as a HDD (Hard Disk Drive) and an SSD (Solid Stage Drive).

[0145] Furthermore, the present invention can be applied to various medical image processing devices in addition to being incorporated into a processor device of an endoscope system such as the first to third embodiments or a capsule endoscope system such as the fourth embodiment.

[0146] Explanation of symbols

[0147] 10-endoscope system, 12-endoscope, 12a-insertion portion, 12b-operation portion, 12c-bending portion, 12d-tip portion, 12e-angle button, 13a, 308-mode switching SW, 14-light source device, 16-processor device, 18-display, 19-user interface, 20a-V-LED, 20b-B-LED, 20c-G-LED, 20d-R-LED, 21-light source control portion, 23-optical path coupling portion, 30a-illumination optical system, 30b-camera optical system, 41-light guide, 45-illumination lens, 46-objective lens , 48-camera sensor, 50-CDS / AGC circuit, 52-A / D converter, 53-image signal input unit, 56-DSP, 58-noise removal unit, 60-signal switching unit, 62-normal image processing unit, 64-special image processing unit, 66-video signal generation unit, 70-inverse gamma conversion unit, 71-Log conversion unit, 72-signal ratio calculation unit, 75-polar coordinate conversion unit, 76-color emphasis processing unit, 77-hue emphasis processing unit, 78-orthogonal coordinate conversion unit, 79-RGB conversion unit, 81-brightness adjustment unit, 81a-1st brightness Information calculation unit, 81b-second brightness information calculation unit, 82-structure emphasis unit, 83-inverse log conversion unit, 84-gamma conversion unit, 85-color saturation emphasis processing switching unit, 86-brightness color difference signal conversion unit, 87-HSV conversion unit, 92-special image processing unit, 96-special image processing unit, 100-endoscope system, 104-blue laser light source, 106-blue-violet laser light source, 108-light source control unit, 110-phosphor, 200-endoscope system, 202-wideband light source, 204-rotating filter, 205-filter switching unit, 206 -Image sensor, 208-filter for normal observation mode, 208a-B filter, 208b-G filter, 208c-R filter, 209-filter for special observation mode, 209a-Bn filter, 209b-G filter, 209c-R filter, 300-capsule endoscope system, 302-capsule endoscope, 302b-image sensor, 302c-image processing unit, 302d-transmitting antenna, 304-transmitting and receiving antenna, 306-capsule receiving device, 400-two-dimensional LUT, SLs-chroma baseline, SLh-hue baseline.

Claims

1. A medical image processing device, comprising: An image signal input unit for inputting a color image signal; A color information acquisition unit that acquires a plurality of color information from the color image signal; and a chroma emphasis processing unit that performs specific chroma emphasis processing on a high chroma range located on the high chroma side relative to a chroma reference line and a low chroma range located on the low chroma side relative to the chroma reference line in a feature space formed by the plurality of color information; The output value included in the low chroma range after the specific chroma emphasis processing is larger than the input value included in the low chroma range before the specific chroma emphasis processing. The output value included in the high chroma range after the specific chroma emphasis processing is smaller than the input value included in the high chroma range before the specific chroma emphasis processing.

2. The medical image processing apparatus according to claim 1, in, The saturation emphasis processing section performs a normal saturation emphasis processing different from the specific saturation emphasis processing. The output value included in the low saturation range after the normal saturation emphasis process is smaller than the input value included in the low saturation range before the normal saturation emphasis process. The output value included in the high saturation range after the normal saturation emphasis process is larger than the input value included in the high saturation range before the normal saturation emphasis process.

3. The medical image processing apparatus according to claim 2, in, The image processing device comprises: The mode switching unit manually switches between the specific saturation emphasis processing and the normal saturation emphasis processing.

4. The medical image processing apparatus according to claim 2, in, The medical image processing device comprises: A saturation emphasis processing switching unit switches to the specific saturation emphasis processing when the index value obtained from the color image signal satisfies the first condition indicating low saturation or high saturation, and switches to the normal saturation emphasis processing when the index value satisfies the second condition indicating intermediate saturation.

5. The medical image processing apparatus according to claim 1, in, The saturation emphasis processing section shifts the saturation reference line according to the mucous membrane color obtained from the color image signal.

6. The medical image processing apparatus according to claim 2, in, The saturation emphasis processing section shifts the saturation reference line according to the mucous membrane color obtained from the color image signal.

7. The medical image processing apparatus according to claim 3, in, The saturation emphasis processing section shifts the saturation reference line according to the mucous membrane color obtained from the color image signal.

8. The medical image processing apparatus according to claim 4, in, The saturation emphasis processing section shifts the saturation reference line according to the mucous membrane color obtained from the color image signal.

9. The medical image processing apparatus according to claim 1, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

10. The medical image processing apparatus according to claim 2, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

11. The medical image processing apparatus according to claim 3, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

12. The medical image processing apparatus according to claim 4, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

13. The medical image processing apparatus according to claim 5, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

14. The medical image processing apparatus according to claim 6, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

15. The medical image processing apparatus according to claim 7, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

16. The medical image processing apparatus according to claim 8, in, The medical image processing device further comprises: The hue emphasis processing unit performs specific hue emphasis processing on the first hue range located on the first hue direction side relative to the hue baseline and the second hue range located on the second hue direction side relative to the hue baseline in the feature space, or performs normal hue emphasis processing different from the specific hue emphasis processing.

17. The medical image processing apparatus according to any one of claims 1 to 16, in, The color image signal includes a blue signal, a green signal and a red signal. The plurality of color information includes a first signal ratio of the blue signal to the green signal and a second signal ratio of the green signal to the red signal.

18. The medical image processing apparatus according to any one of claims 1 to 16, in, The plurality of color information includes color difference signals Cr, Cb obtained from the color image signal.

19. The medical image processing apparatus according to any one of claims 1 to 16, in, The plurality of color information includes a hue H and a saturation S obtained from the color image signal.

20. An endoscope system comprising the medical image processing apparatus according to claim 2 and comprising: A display unit displays at least one of a specific chroma emphasized image obtained from a color image signal subjected to the specific chroma emphasis processing, a normal chroma emphasized image obtained from a color image signal subjected to the normal chroma emphasis processing, or a normal chroma image obtained from a color image signal subjected to neither the specific chroma emphasis processing nor the normal chroma emphasis processing.

21. A working method of a medical image processing device, comprising: The step of inputting a color image signal to an image signal input unit; A step of a color information acquisition unit acquiring a plurality of color information from the color image signal; and The chroma emphasis processing unit performs specific chroma emphasis processing on a high chroma range located on the high chroma side relative to the chroma reference line and a low chroma range located on the low chroma side relative to the chroma reference line in the feature space formed by the plurality of color information, In the step of performing the specific chroma emphasis process, The output value included in the low chroma range after the specific chroma emphasis processing is larger than the input value included in the low chroma range before the specific chroma emphasis processing. The output value included in the high chroma range after the specific chroma emphasis processing is smaller than the input value included in the high chroma range before the specific chroma emphasis processing.

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