Processor for electronic endoscope and electronic endoscope system

Abstract

To allow a part to be emphasized originally to be emphasized appropriately when contour emphasis processing is performed to a captured image while occurrence of a great undershoot is suppressed in a processor for electronic endoscope.SOLUTION: A processor for electronic endoscope acquires a captured image of living tissue and performs image processing. The processor for electronic endoscope has an emphasis operation part 27 for the captured image of the living tissue. The emphasis operation part 27 is provided with: an edge detection part 272 detecting an edge component for each pixel of the captured image of living tissue; an edge component correction part 273 which refers to threshold setting data where threshold of an edge component according to a luminance value is set and corrects an edge component of each pixel detected by the edge detection part 272; and an emphasis processing part 274 which performs contour emphasis processing to the captured image on the basis of the edge component corrected by the edge component correction part 273.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electronic endoscope processor and an electronic endoscope system that acquire images of biological tissue and perform image processing. [Background technology]

[0002] Electronic endoscope devices are used for observing and treating biological tissues inside the human body. Images of biological tissues are captured using an electronic endoscope device, and the captured images are subjected to enhancement processing to highlight specific elements of the biological tissue and then displayed on a display.

[0003] For example, Patent Document 1 describes a contour enhancement device that detects edge components of each pixel of an input luminance signal and weights the detected edge components. This contour enhancement device is configured to add a relatively large weight to edge components related to pixels with a medium level luminance value of the input luminance signal, and add a relatively small weight to edge components related to pixels with a low or high level luminance value of the input luminance signal, which is said to be capable of appropriately enhancing the contours of a subject while preventing the occurrence of large undershoots (cat's eyes) around the contours. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-21905 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, most of the biological tissue to be observed is covered with mucous membrane, which tends to cause specular reflection, and the captured image may include white areas. In the edge enhancement method described in Patent Document 1, the weighting of the high-luminance parts of the image is relatively low, so edge enhancement of the high-luminance parts is suppressed. Therefore, although it is possible to prevent the occurrence of a large undershoot in the above-mentioned whitened parts, edge enhancement is suppressed in the high-luminance parts other than the whitened parts of the captured image, which causes a problem that the image is likely to become blurred.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to prevent the occurrence of large undershoots when performing edge enhancement processing on a captured image in an electronic endoscope processor, while enabling appropriate enhancement of portions that should be enhanced. [Means for solving the problem]

[0007] One aspect of the present disclosure is a processor for an electronic endoscope that acquires an image of a biological tissue and processes the image. an edge detection unit that detects edge components for each pixel of a captured image of biological tissue; an edge component correction unit that refers to threshold setting data in which a threshold value of an edge component corresponding to a luminance value is set, and corrects the edge component of each pixel detected by the edge detection unit; The image capturing apparatus further includes an enhancement processing unit that performs contour enhancement processing on the captured image based on the edge components corrected by the edge component correction unit.

[0008] In the threshold setting data, the threshold may be set so that the threshold for the edge component increases as the luminance value increases.

[0009] When the edge component detected by the edge detection unit exceeds the threshold, the edge component correction unit may correct the edge component based on a parameter set to reduce a portion of the edge component that exceeds the threshold. In this case, the parameter is set such that the portion that exceeds the threshold is reduced as the enhancement strength of the contour enhancement process increases.

[0010] The electronic endoscope processor preferably includes an intensity change unit that changes an intensity of the contour enhancement processing in response to a user's operation, and when the intensity of the contour enhancement processing is changed, the edge component correction unit adjusts the parameter based on the changed intensity.

[0011] The enhancement processing unit may perform the edge enhancement processing according to a method selected from a plurality of edge enhancement processing methods in response to a user operation, in which the plurality of edge enhancement processing methods are associated with different threshold setting data. The edge component correction section corrects the edge components by referring to threshold setting data associated with the selected edge enhancement processing method.

[0012] The enhancement processing unit may perform the edge enhancement processing according to a method selected from a plurality of edge enhancement processing methods in response to a user operation, in which the plurality of edge enhancement processing methods are associated with different parameters. The edge component correction section corrects the edge components by referring to parameters associated with the selected edge enhancement processing method.

[0013] The electronic endoscope processor may further include a light source unit that generates, as illumination light for illuminating the biological tissue, either a first illumination light in a first wavelength band or a second illumination light in a second wavelength band different from the first wavelength band. In this case, the first illumination light and the second illumination light are associated with different threshold setting data. The edge component correction unit corrects the edge component by referring to threshold setting data associated with the illumination light generated by the light source unit out of the first illumination and the second illumination light.

[0014] The electronic endoscope processor may further include a light source unit that generates, as illumination light for illuminating the biological tissue, either a first illumination light in a first wavelength band or a second illumination light in a second wavelength band different from the first wavelength band. In this case, the first illumination light and the second illumination light are associated with different parameters. The edge component correction unit corrects the edge component by referring to a parameter associated with the illumination light generated by the light source unit out of the first illumination and the second illumination light.

[0015] Another aspect of the present disclosure is a method for detecting a signal from an endoscope, comprising: and an endoscope connected to the endoscope processor and equipped with an imaging element for imaging the biological tissue. Effect of the Invention

[0016] According to the above-mentioned electronic endoscope processor and electronic endoscope system, when the electronic endoscope processor performs edge enhancement processing on a captured image, it is possible to appropriately enhance portions that should be enhanced while preventing the occurrence of large undershoots. [Brief description of the drawings]

[0017] [Figure 1] 1 is a block diagram showing an example of a configuration of an electronic endoscope system according to an embodiment; [Diagram 2] 2 is a block diagram showing a configuration of an enhancement calculation unit that performs edge enhancement on an image signal; FIG. [Diagram 3] 11A and 11B are diagrams illustrating processing contents of an exemplary edge component correction unit. [Figure 4] FIG. 13 is a diagram showing an example of threshold setting data set in the enhancement calculation unit; [Diagram 5] 13 is a flowchart showing details of processing by an emphasis calculation unit. [Figure 6] 1A and 1B are diagrams illustrating example images for comparing conventional edge enhancement and edge enhancement according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the electronic endoscope system of this embodiment will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing an example of the configuration of an electronic endoscope system 1 according to this embodiment. As shown in Fig. 1, the electronic endoscope system 1 is a system specialized for medical use, and includes an electronic scope (endoscope) 10, a processor 20, and a monitor 30.

[0019] The processor 20 includes a system controller 21. The system controller 21 executes various programs and performs integrated control of the entire electronic endoscope system 1. The system controller 21 is also connected to an operation panel 26. The system controller 21 changes each operation of the electronic endoscope system 1 and parameters for each operation in response to an instruction from an operator (observer) inputted to the operation panel 26. The system controller 21 outputs clock pulses to each circuit in the electronic endoscope system 1 to adjust the timing of the operation of each part.

[0020] The processor 20 includes a light source device 25 (an example of a light source unit). The light source device 25 emits illumination light L for illuminating a subject such as a biological tissue in a body cavity. The illumination light L includes white light, pseudo white light, or special light. According to an embodiment, the light source device 25 selects one of a mode in which white light or pseudo white light is constantly emitted as the illumination light L, and a mode in which white light, pseudo white light, and special light are alternately emitted as the illumination light L, and preferably emits white light, pseudo white light, or special light based on the selected mode. The white light is light having a flat spectral intensity distribution in the visible light band, and the pseudo white light is light having a non-flat spectral intensity distribution and being a mixture of light of a plurality of wavelength bands. The special light is light of a narrow wavelength band such as blue or green in the visible light band. The light of the blue or green wavelength band is used when observing a specific part of the biological tissue in an emphasized manner. Illumination light L emitted from light source device 25 is condensed by condenser lens 29 onto an incident end surface of LCB (Light Carrying Bundle) 11 and enters LCB 11 . The light source of the light source device 25 is not limited, but may be, for example, an LED, a laser diode, or a high-intensity lamp (for example, a xenon lamp, a metal halide lamp, a mercury lamp, or a halogen lamp).

[0021] Illumination light L incident on the LCB 11 propagates through the LCB 11. The illumination light L propagated through the LCB 11 is emitted from the exit end face of the LCB 11 disposed at the tip of the electronic scope 10, and is irradiated onto the subject via the light distribution lens 12. Return light from the subject illuminated by the illumination light L from the light distribution lens 12 forms an optical image on the light receiving surface of the solid-state imaging element 14 via the objective lens 13.

[0022] The solid-state imaging element 14 is, for example, a single-plate color CCD (Charge Coupled Device) image sensor having a Bayer type pixel arrangement. The solid-state imaging element 14 accumulates an optical image formed at each pixel on the light receiving surface as an electric charge according to the amount of light, and generates and outputs image signals of R (Red), G (Green), and B (Blue). The solid-state imaging element 14 is not limited to a CCD image sensor, and may be replaced with a CMOS (Complementary Metal Oxide Semiconductor) image sensor or other types of imaging devices. The solid-state imaging element 14 may also be equipped with a complementary color filter.

[0023] A driver signal processing circuit 15 is provided within the connection portion of the electronic scope 10. The system controller 21 supplies a clock pulse to the driver signal processing circuit 15. In accordance with the clock pulse supplied from the system controller 21, the driver signal processing circuit 15 drives and controls the solid-state imaging element 14 at a timing synchronized with the frame rate of the video processed by the processor 20. An image signal of a subject is input from the solid-state imaging element 14 to the driver signal processing circuit 15 at a predetermined frame period. The frame period is, for example, 1 / 60 seconds or 1 / 30 seconds. The driver signal processing circuit 15 performs predetermined processing including A / D conversion on the image signal input from the solid-state imaging element 14 and outputs the result to an image input processing unit 22 of the processor 20.

[0024] The image input processing unit 22 performs predetermined signal processing such as noise removal, demosaic processing, and matrix calculation on the image signal sent from the driver signal processing circuit 15 . The image memory 23 is a memory that buffers the image signal sent from the image input processing unit 22 on a frame-by-frame basis. The images of each frame stored in the image memory 23 are subjected to edge enhancement processing in an enhancement calculation unit 27 under the control of the system controller 21. The details of the enhancement calculation unit 27 will be described later. The image signal that has been subjected to edge enhancement processing is output to the image output processing unit 24 in accordance with the timing control by the system controller 21.

[0025] The image output processing unit 24 processes the image signal that has been edge-enhanced by the enhancement calculation unit 27 on a frame-by-frame basis to generate screen data for monitor display, and converts the generated screen data for monitor display into a predetermined video format signal. The converted video format signal is output to the monitor 303. As a result, the image of the subject is displayed on the display screen of the monitor 30.

[0026] Next, the configuration of the emphasis calculation unit 27 will be described with reference to FIG. In FIG. 2, an enhancement calculation unit 27 performs edge enhancement processing on an input image I_in (image signal stored in an image memory 23) sent from the system controller 21, and generates an edge-emphasized output image I_out. As shown in FIG. 2, the enhancement calculation unit 27 includes a YC separation unit 271, an edge detection unit 272, an edge component correction unit 273, an enhancement processing unit 274, an RBG conversion unit 275, and a memory 276. The input image I_in is an RGB signal. The YC separator 271 separates (converts) the RGB signal of the input image I_in into a luminance signal Y and color difference signals Cb and Cr.

[0027] The edge detection unit 272 detects edge components for each pixel from the luminance signal Y obtained in the YC separation unit 271. For the detection of edge components, a known spatial filter such as a Laplacian filter or a Sobel filter can be used. The edge component correction unit 273 corrects the edge component E detected by the edge detection unit 272. The edge component E is corrected in order to appropriately emphasize the portion that should be emphasized while suppressing the occurrence of a large undershoot. When correcting the edge component E, the edge component correction unit 273 accesses threshold setting data. The threshold setting data is stored in the memory 276, which is a non-volatile memory. In the threshold setting data, a threshold value of the edge component is set for the luminance value indicated by the luminance signal Y.

[0028] In one embodiment, the edge component correction unit 273 refers to the threshold setting data and corrects the edge component E of each pixel detected by the edge detection unit 272. For example, the edge component E of each pixel is limited to be equal to or less than a threshold set according to the luminance value of each pixel. Generally, in subjects covered with mucous membranes such as the stomach or large intestine, high-brightness white areas are generated due to specular reflection of the illumination light. Conventionally, when edge enhancement is applied to these white areas, unnatural enhancement (edge ​​undershoot) in which the white areas are outlined in black tends to occur. On the other hand, there is an advantage in that edge undershoot is less likely to occur by limiting the edge component E to a value equal to or less than a threshold value that is preset according to the brightness value.

[0029] The threshold setting data is preferably set so as to prevent edge undershooting in the white-out portion, and to prevent suppression of enhancement of portions of the image that are normally observed other than the white-out portion (e.g., blood vessels). When the edge component E is smaller than the threshold value according to the luminance value, the edge component E is not reduced, so that the enhancement performance is not deteriorated. Therefore, it is preferable not to make the threshold too small so as not to deteriorate the enhancement performance of portions that are normally observed other than the white-out portion.

[0030] The enhancement processing unit 274 generates a luminance signal Yh that has been subjected to contour enhancement processing (edge ​​enhancement) by combining the luminance signal Y generated by the YC separation unit 271 with the edge component Ec that is a component obtained by correcting the edge component E by the edge component correction unit 273. At this time, when the intensity of enhancement is changed in response to a user operation, the edge component Ec is multiplied by a coefficient that increases as the intensity increases, and then the result is added to the luminance signal Y to generate the enhanced luminance signal Yh. The RGB conversion unit 275 converts the color difference signals Cb, Cr separated by the YC separation unit 271 and the luminance signal Yh obtained by the enhancement processing unit 274 into RGB signals to generate an output image I_out.

[0031] In one embodiment, when the edge component E detected by the edge detection unit 272 exceeds the threshold set by the threshold setting data, the edge component correction unit 273 corrects the edge component E based on a parameter set to reduce a portion of the edge component E that exceeds the threshold. In other words, since the portion of the edge component E that exceeds the threshold may be a whiteout portion, the edge component E of this portion is reduced. Here, the parameter is set so that the portion that exceeds the threshold is reduced more as the strength of edge emphasis by the spatial filter for edge detection applied in the edge detection unit 272 increases.

[0032] FIG. 3 shows the process of an exemplary edge component correction unit 273 according to an embodiment. Fig. 3(a) is a diagram showing an example of the distribution of luminance and edge components for multiple pixels included in a partial region of an input image, detected by the edge detection unit 272. In Fig. 3(a), part A is a part that is normally observed other than the white-shaded part, and parts B and C are assumed to be the white-shaded parts. In addition, for the example of FIG. 3(a), assume that the threshold shown in FIG. 3(b) is set by the threshold setting data. In this case, if the edge component detected for a certain pixel is equal to or less than the threshold set according to the luminance value, the edge component is not substantially corrected. On the other hand, if the edge component detected for a certain pixel is greater than the threshold set according to the luminance value, the edge component is corrected based on parameters set to reduce the part of the detected edge component that exceeds the threshold. In FIG. 3(b), the reduced edge component is indicated by a dotted line. In the example of FIG. 3(a), part A is not corrected, but parts B and C are larger than a threshold value set according to the brightness value, so they are corrected so that the parts exceeding the threshold value are reduced.

[0033] If the rate of decrease in the portion exceeding the threshold is r (0≦r<1), the parameters are set to satisfy the following formula (1). Here, f is a function of the edge enhancement strength S, and the parameters are set within the function f defined here. r = f(S)…(1)

[0034] In one embodiment, a function f=α×S is defined. Here, the parameter α is set so that the reduction rate r is a specific value of 0≦r<1 according to the edge enhancement strength S. For example, when the edge enhancement strength S is set to be variable among six levels of 1 to 6, the values ​​of the parameter α when the edge enhancement strength S is 1 to 6 are set to 1 / 4, 1 / 8, 1 / 12, 1 / 16, 1 / 20, and 1 / 24, respectively, so that the reduction rate r is set to 0.25 regardless of the edge enhancement strength S. It is not necessary to keep the reduction rate r constant regardless of the edge enhancement strength S, and the function f may be defined so that the reduction rate r changes according to the edge enhancement strength S as long as the reduction rate r is within the range of 0≦r<1.

[0035] By correcting the edge component E based on parameters set to reduce the portion of the edge component E detected by the edge detection unit 272 that exceeds a threshold, it is possible to suppress edge undershoot in the whiteout portion even when the strength of edge emphasis is increased (i.e., when strong emphasis is applied).

[0036] The function f in formula (1) is not limited to a function using a parameter that changes linearly according to the magnitude of the edge enhancement strength S as defined by f=α×S, but may use a parameter that changes non-linearly according to the magnitude of the edge enhancement strength S. Also, the function f of the edge enhancement strength S may be different for positive and negative edge components.

[0037] In the enhancement calculation unit 27 of one embodiment, the intensity of edge enhancement is set to be changeable, and the observer of the monitor 30 is configured to set a desired intensity from among a plurality of intensities by operating the operation panel 26. In this case, as described above, the enhancement processing unit 274 generates an enhanced luminance signal Yh by adding the luminance signal Y generated by the YC separation unit 271 and the edge component obtained by multiplying the corrected edge component Ec by a coefficient that increases as the intensity increases. In other words, the enhancement processing unit 274 functions as an intensity change unit that changes the intensity of edge enhancement in response to a user operation. When the intensity of the edge enhancement process is changed, the edge component correction unit 273 adjusts the above parameters based on the changed intensity, thereby making it possible to perform edge enhancement after setting optimal parameters in response to the intensity of edge enhancement selected by the user.

[0038] In one embodiment, the threshold setting data preferably sets the threshold value such that the threshold value for the edge component increases as the luminance value increases, in order to suppress edge undershoot in the whiteout portion, which becomes more noticeable as the luminance value increases. In the example shown in Fig. 3(b), the threshold value of the edge component increases linearly with respect to the luminance value, but this is not limited to the above. Fig. 4 shows another example of threshold setting data. As shown in Fig. 4(a) to (c), the threshold value of the edge component with respect to the luminance value may be set nonlinearly with respect to the luminance value, or there may be a region where the threshold value for the luminance value is partially constant. As shown in FIG. 3(b), when the threshold value of the edge component is increased linearly with respect to the luminance value, it is preferable to determine the slope taking into account the extent to which edge components in areas with high luminance values ​​are required for edge undershoot to be visible in the enhanced image. In addition, although Figure 3 (b) and Figures 4 (a) to (c) show the case where the absolute value of the threshold is equal depending on whether the edge component is positive or negative, this is not limited to the case, and the absolute value of the threshold may be changed depending on whether the edge component is positive or negative.

[0039] Next, the operation of the processor 20 of the present embodiment will be described with reference to FIG. The processor 20 continuously monitors whether the intensity of edge enhancement has changed, and when the intensity of edge enhancement has changed (step S2: YES), the processor 20 calculates the reduction rate r when reducing the portion of the edge component detected from the input image that exceeds the threshold value based on the above formula (1) (step S4). The intensity of edge enhancement is changed based on, for example, an operational input to the operation panel 26, as described above.

[0040] The processor 20 acquires an image signal (current frame) from the image input processing unit 22 on a frame-by-frame basis (step S6), and stores the image signal in the image memory 23. The enhancement calculation unit 27 performs the processes of steps S8 to S22 on the current frame. The emphasis calculation unit 27 of the processor 20 sets each pixel of the current frame as a pixel of interest, and performs the processes of steps S8 to S18 on all pixels (step S20: NO). The emphasis calculation unit 27 calculates a threshold T by referring to threshold setting data based on the luminance value of the pixel of interest (step S8). The emphasis calculation unit 27 calculates an edge component E from the luminance values ​​of the pixel of interest and its surrounding pixels (step S10). The emphasis calculation unit 27 calculates an edge component D (=ET) of a portion of the edge component E found in step S10 that exceeds the threshold T (step S12). Note that the edge component and threshold may be positive or negative as shown in FIG. 3, but the threshold T and edge component E mentioned in this flowchart are absolute values.

[0041] If D>0 (step S14: YES), the edge component E calculated in step S10 substantially contains a portion that exceeds the threshold T, and so the edge component E calculated in step S10 is corrected. Specifically, the reduction rate r calculated in step S4 is used to calculate Ec=r×D+T, thereby reducing the portion of the edge component E calculated in step S10 that exceeds the threshold T, thereby calculating the corrected edge component Ec (step S16). Then, the emphasis calculation unit 27 adds the corrected edge component Ec to the luminance value of the pixel of interest, and calculates the pixel value (RGB value) of the pixel of interest (step S18). This allows the pixel value of the pixel of interest after emphasis to be obtained.

[0042] If the processing has been completed for all pixels of the current frame (step S20: YES), the processor 20 converts the edge-enhanced image of the current frame into a video format signal, and displays the image on the monitor 30 (step S22). If the processing has not ended (step S24: NO), the processor 20 returns to step S2 to process the next frame.

[0043] As described above, according to the electronic endoscope system 1 of the present embodiment, an edge component is detected for each pixel of the captured image of the biological tissue, and the edge component of each detected pixel is corrected by referring to the threshold setting data in which the threshold value of the edge component is set according to the luminance value. Furthermore, an edge enhancement process is performed for each pixel based on the corrected edge component. Therefore, by limiting the edge component E to a value equal to or less than the threshold value previously set according to the luminance value, the image displayed on the monitor 30 is less likely to have unnatural enhancement (edge ​​undershoot) in which the white part is bordered with a black border. Preferably, when the detected edge component exceeds the threshold value indicated by the threshold setting data, the edge component is corrected based on a parameter set to reduce the portion of the edge component that exceeds the threshold value. At this time, the parameter is set so that the portion that exceeds the threshold value is reduced as the enhancement strength of the edge enhancement process increases. This makes it possible to appropriately enhance the portion that should be enhanced while preventing the occurrence of a large undershoot.

[0044] Referring to Figure 6, there are shown an image (original image) of exemplary biological tissue before enhancement, an image obtained by performing edge enhancement on the original image using a conventional edge enhancement method (conventional method), and an image obtained by performing edge enhancement on the original image using the edge enhancement method (example) of this embodiment. As shown in the original image, when imaging biological tissue, specular reflection of illumination light from a subject covered with mucous membranes such as the stomach or large intestine produces high-brightness blank areas W in addition to blood vessel areas BV. When edge enhancement is applied to the blank areas W using a conventional method, unnatural enhancement (edge ​​undershoot) occurs in which the blank areas are outlined in black, and it has been confirmed that the blood vessel areas BV are not sufficiently enhanced and become blurred. In contrast, in the case of the embodiment, it can be seen that the edge undershoot is suppressed to an unnoticeable level, and the blood vessel portion BV is appropriately emphasized, making it easy to observe.

[0045] In one embodiment, the enhancement calculation unit 27 performs edge enhancement processing according to an edge enhancement processing method selected from a plurality of edge enhancement processing methods in response to a user operation. In this case, the plurality of edge enhancement processing methods are associated with different threshold setting data. The edge component correction unit 273 corrects the edge component E by referring to the threshold setting data associated with the selected edge enhancement processing method. This allows the observer to switch between edge enhancement processing methods such as spatial filters according to their purpose or preference by inputting to the operation panel 26, enabling flexible operation according to the observer. For example, multiple spatial filters may be prepared for edge enhancement. Some of these may be specialized for enhancing high-frequency portions in a captured image, while others may be specialized for enhancing low-frequency portions. In this case, when the spatial filter to be applied is switched, the corresponding threshold setting data and the parameters or function f (see formula (1)) used for calculating the rate of decrease r are changed. Such a change process is performed at the points corresponding to steps S2 to S4 in the flowchart of FIG. 5.

[0046] In one embodiment, the light source device 25 generates, as the illumination light, either a first illumination light in a first wavelength band or a second illumination light in a second wavelength band different from the first wavelength band. The first illumination light and the second illumination light are not limited as long as they are lights with different spectra. As an example, the first illumination light is normal light (white light or pseudo-white light) and the second illumination light is special light (light with a narrower wavelength band than the wavelength band of the normal light). Since an image observed with the special light can be obtained that is different from an image observed with the normal light depending on the absorption characteristics of the biological tissue, a certain characteristic part of the biological tissue can be observed with emphasis, which makes it easier to find a lesion or the like in the biological tissue. Since images obtained by the first illumination light and the second illumination light are different, it is preferable that threshold setting data is associated with each illumination light. Then, the edge component correction unit 273 corrects the edge component E by referring to the threshold setting data associated with the illumination light generated by the light source device 25 out of the first illumination light and the second illumination light. This makes it possible to set an appropriate threshold according to the illumination light. At that time, it is preferable to change the parameter or function f (see formula (1)) used when calculating the reduction rate r according to the illumination light. In this case, the threshold setting data or the parameter or function f to be referred to is changed according to the observer's operation input to the operation panel 26 that selects either the first illumination light or the second illumination light. Such a change process is performed at a location corresponding to steps S2 to S4 in the flowchart of FIG. 5.

[0047] In one embodiment, a plurality of edge enhancement processing methods are provided in the enhancement calculation unit 27, and the light source device 25 is configured to emit a plurality of illumination lights with different spectra. In response to an operation by an observer, an edge enhancement processing method (spatial filter) and an illumination light are selected. In this case, it is preferable that the threshold setting data, parameters, or functions f to be applied are set in correspondence with all combinations of spatial filters and illumination lights.

[0048] The above describes in detail the electronic endoscope processor and electronic endoscope system of the present invention. However, the electronic endoscope processor and electronic endoscope system of the present invention are not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0049] 1. Electronic endoscope system 10...Electronic scope 11...LCB 12...Light distribution lens 13...Objective lens 14...Solid-state image sensor 15...Driver signal processing circuit 20…Processor 21…System controller 22...Image input processing unit 23...Image memory 24...Image output processing section 25...Light source device 26...Operation panel 27...emphasis calculation section 271...YC separation section 272…Edge detection section 273...Edge component correction unit 274...Emphasis processing unit 275…RBG conversion section 276…Memory 29...Condenser lens 30…Monitor

Claims

1. A processor for an electronic endoscope that acquires an image of a biological tissue and processes the image, an edge detection unit that detects edge components for each pixel of a captured image of biological tissue; an edge component correction unit that refers to threshold setting data in which a threshold value of an edge component corresponding to a luminance value is set, and corrects the edge component of each pixel detected by the edge detection unit; an enhancement processing unit that performs contour enhancement processing on the captured image based on the edge components corrected by the edge component correction unit, Processor for electronic endoscopes.

2. In the threshold setting data, the threshold is set so that the threshold for the edge component increases as the luminance value increases.

2. A processor for an electronic endoscope according to claim 1.

3. the edge component correction unit corrects the edge component based on a parameter set to reduce a portion of the edge component that exceeds the threshold when the edge component detected by the edge detection unit exceeds the threshold; the parameters are set such that the greater the enhancement intensity of the edge enhancement process, the lower the portion exceeding the threshold value.

3. A processor for an electronic endoscope according to claim 1 or 2.

4. an intensity change unit that changes an intensity of the edge enhancement processing in response to a user operation; when the enhancement intensity of the contour enhancement processing is changed, the edge component correction unit adjusts the parameter based on the changed enhancement intensity.

4. A processor for an electronic endoscope according to claim 3.

5. the enhancement processing unit performs the edge enhancement processing in accordance with an edge enhancement processing method selected in response to a user operation from among a plurality of edge enhancement processing methods; the plurality of edge enhancement processing methods are associated with different threshold setting data, the edge component correction unit corrects the edge components by referring to threshold setting data associated with the selected edge enhancement processing method; 3. A processor for an electronic endoscope according to claim 1 or 2.

6. the enhancement processing unit performs the edge enhancement processing in accordance with an edge enhancement processing method selected in response to a user operation from among a plurality of edge enhancement processing methods; the plurality of edge enhancement processing methods are associated with different parameters, the edge component correction unit corrects the edge components by referring to parameters associated with the selected edge enhancement processing method.

4. A processor for an electronic endoscope according to claim 3.

7. a light source unit that generates, as illumination light for illuminating the biological tissue, either a first illumination light in a first wavelength band or a second illumination light in a second wavelength band different from the first wavelength band; the first illumination light and the second illumination light are associated with different threshold setting data, the edge component correction unit corrects the edge component by referring to threshold setting data associated with the illumination light generated by the light source unit out of the first illumination and the second illumination light; 3. A processor for an electronic endoscope according to claim 1 or 2.

8. a light source unit that generates, as illumination light for illuminating the biological tissue, either a first illumination light in a first wavelength band or a second illumination light in a second wavelength band different from the first wavelength band; the first illumination light and the second illumination light are associated with different parameters, the edge component correction unit corrects the edge component by referring to a parameter associated with the illumination light generated by the light source unit out of the first illumination and the second illumination light; 4. A processor for an electronic endoscope according to claim 3.

9. The endoscope processor according to claim 1 or 2, an endoscope connected to the endoscope processor and equipped with an imaging element for imaging the biological tissue.

Images