Processor for electronic endoscope and electronic endoscope system

Abstract

In one aspect of the present disclosure, the processor for an electronic endoscope acquires a captured image of a biological tissue and performs image processing. The electronic endoscope processor is provided with an enhancement calculation unit (27) for capturing an image of a biological tissue. The enhancement calculation unit (27) is provided with: an edge detection unit (272) for detecting an edge component of each pixel in a captured image of biological tissue; an edge component correction unit 273 that corrects the edge component of each pixel detected by the edge detection unit 272 by referring to threshold setting data in which a threshold of the edge component corresponding to the luminance value is set; and an enhancement processing unit 274 that performs contour enhancement processing on the captured image on the basis of the edge component corrected by the edge component correction unit 273.

Description

Technical Field

[0001] The present invention relates to a processor for an electronic endoscope and an electronic endoscope system that acquire a captured image of a biological tissue and perform image processing thereon. Background Art

[0002] An electronic endoscope device is used for observing and treating biological tissues inside the human body. A captured image is obtained by photographing a biological tissue using the electronic endoscope device, and the obtained captured image is enhanced to highlight specific elements of the biological tissue in the captured image and displayed on a display.

[0003] For example, Japanese Patent Application Laid-Open No. 2009-21905 discloses a contour enhancement device that detects edge components of each pixel of an input luminance signal and weights the detected edge components. In this contour enhancement device, it is configured to assign a relatively large weight to the edge components of pixels having a medium luminance value of the input luminance signal, and assign a relatively small weight to the edge components of pixels having a low or high luminance value of the input luminance signal, thereby being able to prevent a large undershoot (cat's eye) from occurring around the contour and being able to appropriately enhance the contour of the subject. Summary of the Invention

[0004] Problems to be Solved by the Invention

[0005] Generally, since a large part of the biological tissue to be observed is covered with mucous membrane, specular reflection easily occurs, and thus there are sometimes whitened portions in the captured image.

[0006] In the contour enhancement method described in Japanese Patent Application Laid-Open No. 2009-21905, since the weighting of the high-luminance portions in the image is relatively low, the contour enhancement of the high-luminance portions is suppressed. Therefore, although it is possible to prevent a large undershoot from occurring in the whitened area, since the contour enhancement of the high-luminance portions other than the whitened area in the captured image is also suppressed, there is a problem that the image tends to be blurred.

[0007] Therefore, an object of the present invention is to suppress the occurrence of a large undershoot and be able to appropriately enhance a portion that should be enhanced when performing contour enhancement processing on a captured image in a processor for an electronic endoscope.

[0008] Means for Solving the Problems

[0009] One aspect of the present disclosure is a processor for an electronic endoscope that acquires a captured image of a biological tissue and performs image processing. The processor for the electronic endoscope includes: an edge detection unit that detects edge components of each pixel in the captured image of the biological tissue; an edge component correction unit that corrects the edge components of each pixel detected by the edge detection unit with reference to threshold setting data in which a threshold for the edge component corresponding to a luminance value is set; and 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.

[0010] In the threshold setting data, the threshold for the edge component can be set in such a way that the threshold increases as the luminance value increases.

[0011] When the edge component detected by the edge detection unit exceeds the threshold, the edge component correction unit can correct the edge component according to a set parameter to reduce the portion of the edge component that exceeds the threshold. In this case, the parameter is set such that the greater the enhancement intensity of the contour enhancement processing, the smaller the portion that exceeds the threshold.

[0012] The processor for the electronic endoscope preferably includes an intensity change unit that can change the enhancement intensity of the contour enhancement processing according to a user operation. When the enhancement intensity of the contour enhancement processing changes, the edge component correction unit adjusts the parameter according to the changed intensity.

[0013] The enhancement processing unit can perform the contour enhancement processing according to a contour enhancement processing method, where the contour enhancement processing method is selected from a plurality of contour enhancement processing methods by a user operation. In this case, the plurality of contour enhancement processing methods are respectively associated with different threshold setting data.

[0014] The edge component correction unit corrects the edge component with reference to the threshold setting data associated with the selected contour enhancement processing method.

[0015] The enhancement processing unit can also perform the contour enhancement processing according to a contour enhancement processing method, where the contour enhancement processing method is selected from a plurality of contour enhancement processing methods by a user operation. In this case, the plurality of contour enhancement processing methods are respectively associated with different parameters.

[0016] The edge component correction unit corrects the edge component with reference to the parameter associated with the selected contour enhancement processing method.

[0017] The processor for an electronic endoscope may further include a light source unit that can generate either first illumination light in a first wavelength band or second illumination light in a second wavelength band different from the first wavelength band as the illumination light for illuminating the biological tissue. In this case, the first illumination light and the second illumination light are respectively associated with different threshold setting data.

[0018] The edge component correction unit corrects the edge components with reference to the threshold setting data associated with the illumination light generated by the light source unit among the first illumination and the second illumination light.

[0019] The processor for an electronic endoscope may further include a light source unit that can generate either first illumination light in a first wavelength band or second illumination light in a second wavelength band different from the first wavelength band as the illumination light for illuminating the biological tissue. In this case, the first illumination light and the second illumination light are respectively associated with different parameters.

[0020] The edge component correction unit corrects the edge components with reference to the parameters associated with the illumination light generated by the light source unit among the first illumination and the second illumination light.

[0021] Another aspect of the present disclosure is an endoscope system including the processor for an endoscope and an endoscope, wherein the endoscope includes an imaging element connected to the processor for an endoscope and configured to image the biological tissue.

[0022] Advantageous Effects of the Invention

[0023] According to the processor for an electronic endoscope and the electronic endoscope system, when performing contour enhancement processing on a captured image in the processor for an electronic endoscope, generation of a large undershoot is suppressed, and a portion that should be enhanced can be appropriately enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A block diagram showing an example of the structure of an electronic endoscope system in one embodiment.

[0025] Figure 2 A block diagram showing the structure of an enhancement operation unit that performs edge enhancement of an image signal.

[0026] Figure 3 An explanatory diagram showing the processing content of an exemplary edge component correction unit.

[0027] Figure 4 A diagram showing an example of threshold setting data set in the enhancement operation unit.

[0028] Figure 5A flowchart showing the details of the processing of the enhancement operation unit.

[0029] Figure 6 A diagram showing an image example for comparing the existing edge enhancement and the edge enhancement involved in the implementation. Detailed implementation

[0030] Hereinafter, the electronic endoscope system of the present embodiment will be described in detail with reference to the accompanying drawings.

[0031] Figure 1 A block diagram showing an example of the structure of the electronic endoscope system 1 in the present embodiment. As Figure 1 shown, the electronic endoscope system 1 is a system dedicated to medical use and includes an electronic observer (endoscope) 10, a processor 20, and a monitor 30.

[0032] The processor 20 includes a system controller 21. The system controller 21 executes various programs and comprehensively controls the entire electronic endoscope system 1. In addition, the system controller 21 is connected to the operation panel 26. The system controller 21 changes the operations of the electronic endoscope system 1 and the parameters for each operation according to the instructions of the operator (observer) input to the operation panel 26. The system controller 21 outputs clock pulses for adjusting the timing of the operations of each part to each circuit in the electronic endoscope system 1.

[0033] 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 an object such as biological tissue in a body cavity. The illumination light L includes white light, pseudo-white light, or special light. According to one embodiment, the light source device 25 preferentially selects any one of a mode of always emitting white light or pseudo-white light as the illumination light L and a mode of alternately emitting white light or pseudo-white light and special light as the illumination light L, and emits white light, pseudo-white light, or special light according to the selected mode. White light is light having a flat spectral intensity distribution in the visible light band, and pseudo-white light is light having a non-flat spectral intensity distribution and mixed with light in multiple bands. Special light is light in a narrow band in the visible light band, such as blue or green. The light in the blue or green band is used to enhance and observe a specific part of biological tissue. The illumination light L emitted from the light source device 25 is condensed by a condenser lens 29 on the incident end face of the light guide fiber bundle (LCB) 11 and then enters the LCB 11.

[0034] The light source of the light source device 25 is not limited. For example, it can be an LED, a laser diode, a high-intensity lamp (such as a xenon lamp, a metal halide lamp, a mercury lamp, or a halogen lamp), etc.

[0035] The illumination light L incident on the LCB 11 propagates within the LCB 11. The illumination light L that has propagated within the LCB 11 exits from the exit end face of the LCB 11 disposed at the front end of the electronic viewer 10 and irradiates the subject via the light distribution lens 12. The light returned from the subject forms an optical image on the light receiving surface of the solid-state imaging device 14 via the objective lens 13, and the subject is illuminated by the illumination light L from the light distribution lens 12.

[0036] The solid-state imaging device 14 is, for example, a single-plate color CCD (Charge Coupled Device) image sensor having a Bayer-type pixel arrangement. The solid-state imaging device 14 accumulates the optical image formed on each pixel of the light receiving surface as charges that vary with the amount of light, generates R (Red), G (Green), and B (Blue) image signals, and then outputs them. In addition, the solid-state imaging device 14 is not limited to a CCD image sensor and can be replaced with a Complementary Metal Oxide Semiconductor (CMOS) image sensor or other types of imaging devices. The solid-state imaging device 14 can also be a device equipped with a complementary color filter.

[0037] A driver signal processing circuit 15 is provided within the connection portion of the electronic viewer 10.

[0038] The system controller 21 supplies a clock pulse to the driver signal processing circuit 15. The driver signal processing circuit 15 drives and controls the solid-state imaging device 14 in synchronization with the frame rate of the video processed on the processor 20 side according to the clock pulse supplied from the system controller 21. The image signal of the subject from the solid-state imaging device 14 is input to the driver signal processing circuit 15 at a predetermined frame period. The frame period is, for example, 1 / 60 second or 1 / 30 second. The driver signal processing circuit 15 performs predetermined processing including A / D conversion on the image signal input from the solid-state imaging device 14 and outputs it to the image input processing unit 22 of the processor 20.

[0039] The image input processing unit 22 performs predetermined signal processing on the image signal sent from the driver signal processing circuit 15, such as noise reduction processing, demosaicing processing, matrix operation, etc.

[0040] The image memory 23 is a memory that buffers the image signal sent from the image input processing unit 22 in units of frames. Each frame image stored in the image memory 23 is sequentially subjected to edge enhancement processing in the enhancement operation unit 27 under the control of the system controller 21. The enhancement operation unit 27 will be described in detail later. The image signal after the edge enhancement processing is output to the image output processing unit 24 according to the timing control of the system controller 21.

[0041] The image output processing unit 24 processes the image signal that has been edge-enhanced by the enhancement operation unit 27 in units of frames, generates picture data for monitor display, and converts the generated picture data for monitor display into a signal of a specified video format. The converted video format signal is output to the monitor 303. Thus, the image of the subject is displayed on the display screen of the monitor 30.

[0042] Next, refer to Figure 2 to describe the structure of the enhancement operation unit 27.

[0043] In Figure 2 the enhancement operation unit 27 performs edge enhancement processing on the input image I_in (the image signal stored in the image memory 23) sent from the system controller 21, and generates an output image I_out with edge enhancement applied.

[0044] As Figure 2 shown, the enhancement operation 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.

[0045] The input image I_in is an RGB signal. The YC separation unit 271 separates (converts) the RGB signal of the input image I_in into a luminance signal Y and color difference signals Cb and Cr.

[0046] The edge detection unit 272 detects edge components of the luminance signal Y obtained in the YC separation unit 271 in units of pixels. The detection of edge components can use known spatial filters, such as a Laplace filter or a Sobel filter, etc.

[0047] The edge component correction unit 273 corrects the edge component E detected in the edge detection unit 272. Correcting the edge component E is to suppress large undershoots and appropriately enhance parts that should be enhanced. 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. The threshold setting data sets the threshold of the edge component for the luminance value indicated by the luminance signal Y.

[0048] In one embodiment, the edge component correction unit 273 corrects the edge component E of each pixel detected by the edge detection unit 272 with reference to the threshold setting data. For example, the edge component E of each pixel is limited to be below the threshold set according to the luminance value of each pixel.

[0049] Generally, on a subject covered with mucosa such as the stomach and large intestine, specular reflection caused by illumination light generates a highly bright whitish area. Conventionally, when performing edge enhancement on this whitish area, it is easy to generate unnatural enhancement (undershoot), that is, black appears at the edge of the whitish area. In contrast, by restricting the edge component E below a threshold value set in advance according to the luminance value, there is an advantage that it is difficult to generate this undershoot.

[0050] The threshold setting data is preferably set so as not to generate undershoot at the edge of the whitish area, and the enhancement of the part other than the whitish area in the image that becomes the object of normal observation (for example, the blood vessel part) is not suppressed. If the edge component E is less than the threshold value corresponding to the luminance value, the edge component E will not be reduced and the enhancement performance will not be reduced. Therefore, it is preferable that the threshold is not set too small so as not to reduce the enhancement performance of the part other than the whitish area that becomes the object of normal observation.

[0051] The enhancement processing unit 274 synthesizes the luminance signal Y generated by the YC separation unit 271 and the edge component Ec (that is, the component obtained by correcting the edge component E by the edge component correction unit 273) to generate a luminance signal Yh subjected to contour enhancement processing (edge enhancement). At this time, when changing the intensity of enhancement according to the user's operation, a coefficient that becomes larger as the intensity increases is multiplied by the edge component Ec and then added to the luminance signal Y to generate the enhanced luminance signal Yh.

[0052] The RBG conversion unit 275 converts the color difference signals Cb and 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 the output image I_out.

[0053] In one embodiment, when the edge component E detected by the edge detection unit 272 exceeds the threshold value set by the threshold setting data, the edge component correction unit 273 corrects the edge component E based on the set parameters to reduce the part of the edge component E that exceeds the threshold value. That is, the part of the edge component E that exceeds the threshold value may be the whitish area, so the edge component E of this area is reduced. Among them, the parameter is set such that the larger the edge enhancement intensity of the edge detection spatial filter applied in the edge detection unit 272, the smaller the part that exceeds the threshold value.

[0054] Figure 3 The processing content of an exemplary edge component correction unit 273 of one embodiment is shown.

[0055] Figure 3 (a) is a diagram showing an example of the distribution of the luminance and edge components of a plurality of pixels included in a partial area of the input image detected by the edge detection unit 272. In Figure 3In (a) thereof, it is assumed that part A is the part that becomes the ordinary observation object outside the whitening area, and parts B and C are the whitening areas.

[0056] In addition, for Figure 3 the example of (a), it is assumed that Figure 3 the threshold value shown in (b) of Figure 3 is set by the threshold setting data. At this time, if the edge component detected for a certain pixel is below the threshold value set according to the luminance value, the edge component is not substantially corrected. On the contrary, if the edge component detected for a certain pixel is greater than the threshold value set according to the luminance value, the edge component is corrected according to the set parameters to reduce the part exceeding the threshold value in the detected edge component. In addition, in

[0057] In Figure 3 the example of (a), although part A is not corrected, since parts B and C exceed the threshold value set according to the luminance value, they are corrected to reduce the part exceeding the threshold value.

[0058] Among them, if the reduction rate of the part exceeding the threshold value is set to r (and 0 ≤ r < 1), the parameter is set to satisfy the following formula (1). Among them, f is a function of the edge enhancement intensity S, and parameters are set in the function f defined here.

[0059] r = f(S)...(1)

[0060] In one embodiment, the function f = α × S is defined. Among them, the parameter α is set to a specific value that makes the reduction rate r satisfy 0 ≤ r < 1 according to the edge enhancement intensity S. For example, when the edge enhancement intensity S is set to be variable between six levels from 1 to 6, by making the values of the parameter α when the edge enhancement intensity S is 1 to 6 be 1 / 4, 1 / 8, 1 / 12, 1 / 16, 1 / 20, 1 / 24 respectively, the reduction rate r can be set to 0.25 regardless of the edge enhancement intensity S. In addition, regardless of the edge enhancement intensity S, it is not necessary to make the reduction rate r constant. As long as the reduction rate r is within the range of 0 ≤ r < 1, the function f can be defined to make the reduction rate r change according to the edge enhancement intensity S.

[0061] The edge component E is corrected according to the set parameters to reduce the part exceeding the threshold value in the edge component E detected by the edge detection unit 272. In this way, even in the case of increasing the edge enhancement intensity (i.e., in the case of strengthening the enhancement), the edge undershoot of the whitening area can be suppressed.

[0062] In addition, the function f in formula (1) is not limited to using parameters that linearly change with the magnitude of the edge enhancement intensity S (which is defined by f = α × S), and parameters that non-linearly change with the magnitude of the edge enhancement intensity S can also be used. Additionally, the function f of the edge enhancement intensity S can also be different depending on the positive or negative of the edge component.

[0063] In the enhancement operation unit 27 of one embodiment, the edge enhancement intensity is set to be changeable, and is configured such that an observer of the monitor 30 can set a desired intensity from a plurality of intensities by operating the operation panel 26. In this case, as described above, the enhancement processing unit 274 adds the luminance signal Y generated by the YC separation unit 271 to the edge component to generate an enhanced luminance signal Yh, where the edge component is obtained by multiplying a coefficient that becomes larger as the intensity increases by the corrected edge component Ec. That is, the enhancement processing unit 274 functions as an intensity change unit that changes the edge enhancement intensity according to the user's operation. When the enhancement intensity of the edge enhancement processing changes, the edge component correction unit 273 adjusts the parameter according to the changed intensity, whereby edge enhancement can be performed on the basis of setting the optimal parameter according to the edge enhancement intensity selected by the user.

[0064] In one embodiment, in the threshold setting data, it is preferable to set the threshold in such a way that the threshold of the edge component becomes larger as the luminance value becomes larger. This is to suppress the edge undershoot in the whitening area, because the larger the luminance value, the more obvious the edge undershoot in the whitening area.

[0065] In Figure 3 the example shown in (b) of Figure 4 it is shown that the threshold of the edge component linearly increases with respect to the luminance value, but it is not limited thereto. Figure 4 Fig.

[0066] Fig. Figure 3 In the case where the threshold of the edge component linearly increases with respect to the luminance value as shown in (b) of

[0067] In addition, in Figure 3 the (b) of Figure 4 or the (a) - (c) of

[0068] Next, with reference to Figure 5 the operation of the processor 20 of the present embodiment will be described.

[0069] The processor 20 sequentially monitors whether the edge enhancement intensity changes. When the edge enhancement intensity changes (step S2: YES), according to the formula (1), the reduction rate r when reducing the part exceeding the threshold in the edge component is calculated (step S4), where the edge component is detected from the input image. As described above, the change in the edge enhancement intensity can be performed, for example, based on the operation input to the operation panel 26.

[0070] The processor 20 obtains an image signal (current frame) from the image input processing unit 22 in units of frames (step S6) and stores it in the image memory 23. The enhancement operation unit 27 performs the processing of steps S8 to S22 on the current frame.

[0071] The enhancement operation unit 27 of the processor 20 takes each pixel of the current frame as the pixel of interest and performs the processing of steps S8 to S18 on all pixels (step S20: NO). The enhancement operation unit 27 calculates the threshold T with reference to the threshold setting data based on the luminance value of the pixel of interest (step S8). The enhancement operation unit 27 calculates the edge component E based on the luminance values of the pixel of interest and its surrounding pixels (step S10). The enhancement operation unit 27 calculates the edge component D (= E - T) of the part exceeding the threshold T in the edge component E obtained in step S10 (step S12). In addition, as Figure 3 shown, the edge component and the threshold can be positive or negative, but the threshold T and the edge component E mentioned in this flowchart are absolute values.

[0072] When D > 0 (step S14: YES), since there is substantially a part exceeding the threshold T in the edge component E obtained in step S10, the edge component E calculated in step S10 is corrected. Specifically, by using the reduction rate r obtained in step S4, Ec = r × D + T is calculated to reduce the part exceeding the threshold T in the edge component E obtained in step S10, thereby calculating the corrected edge component Ec (step S16). Then, the enhancement operation 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). Thus, the pixel value after enhancement of the pixel of interest is obtained.

[0073] When the processing of all pixels of the current frame is completed (step S20: YES), the processor 20 converts the image of the current frame with edge enhancement into a video format signal and displays the image on the monitor 30 (step S22).

[0074] In the case where the process is not finished (step S24: NO), the processor 20 returns to step S2 to process the next frame.

[0075] As described above, in the electronic endoscope system 1 according to the present embodiment, edge components of each pixel of a captured image of a biological tissue are detected, and the detected edge components of each pixel are corrected with reference to threshold setting data in which a threshold of the edge component corresponding to the luminance value is set. Then, edge enhancement processing is performed on each pixel based on the corrected edge components. Therefore, by restricting the edge component E below the threshold set in advance according to the luminance value, unnatural enhancement (edge undershoot), such as a black edge being formed in a whitened area, hardly appears in the image displayed on the monitor 30.

[0076] Preferably, if the detected edge component exceeds the threshold indicated by the threshold setting data, the edge component is corrected according to the set parameter to reduce the portion of the edge component that exceeds the threshold. At this time, the parameter is set such that the greater the enhancement intensity of the edge enhancement processing, the smaller the portion that exceeds the threshold. Therefore, it is possible to suppress the occurrence of a large undershoot and appropriately enhance the portion that should be enhanced originally.

[0077] Reference Figure 6 shows a captured image (original image) of an exemplary biological tissue before enhancement, an image in the case where the original image is edge-enhanced by an existing edge enhancement method (existing method), and an image in the case where the original image is edge-enhanced by the edge enhancement method (embodiment) of the present embodiment.

[0078] As shown in the original image, when capturing an image of a biological tissue, in addition to the blood vessel part BV, a high-luminance whitened area W is generated, which is caused by specular reflection of illumination light of a subject covered with a mucous membrane such as the stomach or the large intestine. When edge enhancement is performed on the whitened area W by an existing method, it is confirmed that unnatural enhancement (edge undershoot) occurs, that is, a black color appears at the edge of the whitened area, and the blood vessel part BV is not sufficiently enhanced and becomes blurred.

[0079] In contrast, in the embodiment, the edge undershoot is suppressed to an insignificant level, and the blood vessel part BV is appropriately enhanced and becomes easy to observe.

[0080] In one embodiment, the enhancement operation unit 27 can perform edge enhancement processing according to an edge enhancement processing method, where the edge enhancement processing method is selected from a plurality of edge enhancement processing methods through a user operation. In this case, the plurality of edge enhancement processing methods are respectively associated with different threshold setting data. The edge component correction unit 273 corrects the edge component E with reference to the threshold setting data, where the threshold setting data is associated with the selected edge enhancement processing method. Thus, the observer can switch between edge enhancement processing methods such as a spatial filter by inputting to the operation panel 26 according to the purpose or preference, so as to achieve flexible application according to the observer's operation.

[0081] For example, a plurality of spatial filters can be prepared for edge enhancement. Among them, there is a spatial filter that specifically enhances the high-frequency part of the captured image, and there can also be a spatial filter that specifically enhances the low-frequency part. In this case, if the applied spatial filter is switched, the parameters or the function f (refer to formula (1)) when calculating the corresponding threshold setting data or the decay rate r are changed. In Figure 5 the flowchart, the above change process is performed at positions corresponding to steps S2 to S4.

[0082] In one embodiment, the light source device 25 can generate either the first illumination light in the first wavelength band or the second illumination light in a second wavelength band different from the first wavelength band as the illumination light. 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 ordinary light (white light or pseudo-white light), and the second illumination light is special light (light with a narrower wavelength band than ordinary light). The observation image using the special light can obtain an image different from the observation image under ordinary light according to the absorption characteristics of the biological tissue, so that a certain characteristic part of the biological tissue can be enhanced for observation, and it is easier to find the diseased part of the biological tissue, etc.

[0083] Since the images obtained by the first illumination light and the second illumination light are different, the threshold setting data is preferably associated with the respective illumination lights. Moreover, the edge component correction unit 273 corrects the edge component E with reference to the threshold setting data associated with the illumination light generated by the light source device 25 among the first illumination and the second illumination light. Thus, an appropriate threshold can be set according to the illumination light. At this time, it is preferable to change the parameters or the function f (refer to formula (1)) when calculating the decay rate r according to the illumination light. In this case, the threshold setting data, parameters, or function f to be referred to are changed according to the operation input to the operation panel 26 when the observer selects the first illumination light or the second illumination light. In Figure 5 the flowchart, the above change process is performed at positions corresponding to steps S2 to S4.

[0084] In one embodiment, a plurality of edge enhancement processing methods are provided in the enhancement operation unit 27, and the light source device 25 is configured to emit a plurality of illumination lights having different spectra. According to the operation of the observer, an edge enhancement processing method (spatial filter) is selected, and an illumination light is selected. In this case, it is preferable to set the threshold setting data, parameters, or function f to be applied corresponding to all combinations of the spatial filter and the illumination light.

[0085] As described above, the processor for an electronic endoscope and the electronic endoscope system of the present invention have been described in detail. However, the processor for an electronic endoscope and the electronic endoscope system of the present invention are not limited to the above-described embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

[0086] The present invention relates to a patent application of Japanese Patent Application No. 2023-2336 filed with the Japan Patent Office on January 11, 2023, and the entire contents of this application are incorporated herein by reference.

Claims

1. An endoscope processor for an electronic endoscope, which is an endoscope processor for acquiring a captured image of a biological tissue and performing image processing, and includes: an edge detection unit for detecting edge components of each pixel of the captured image of the biological tissue; an edge component correction unit for correcting the edge components of each pixel detected by the edge detection unit with reference to threshold setting data, wherein, the threshold setting data sets thresholds of edge components corresponding to luminance values; an enhancement processing unit for performing contour enhancement processing on the captured image based on the edge components corrected by the edge component correction unit.

2. The endoscope processor for an electronic endoscope according to claim 1, wherein, in the threshold setting data, the thresholds are set in such a way that the thresholds of edge components increase as the luminance values increase.

3. The endoscope processor for an electronic endoscope according to claim 1 or 2, wherein, when the edge components detected by the edge detection unit exceed the threshold, the edge component correction unit corrects the edge components based on set parameters to reduce the part of the edge components that exceeds the threshold, and the parameters are set such that the greater the enhancement intensity of the contour enhancement processing, the smaller the part that exceeds the threshold.

4. The endoscope processor for an electronic endoscope according to claim 3, which includes an intensity change unit capable of changing the enhancement intensity of the contour enhancement processing according to a user operation. When the enhancement intensity of the contour enhancement processing changes, the edge component correction unit adjusts the parameters according to the changed intensity.

5. The endoscope processor for an electronic endoscope according to claim 1 or 2, wherein, the enhancement processing unit can perform the contour enhancement processing according to a contour enhancement processing method, wherein the contour enhancement processing method is selected from a plurality of contour enhancement processing methods by a user operation, the plurality of contour enhancement processing methods are respectively associated with different threshold setting data, and the edge component correction unit corrects the edge components with reference to the threshold setting data associated with the selected contour enhancement processing method.

6. The endoscope processor for an electronic endoscope according to claim 3, wherein, the enhancement processing unit can perform the contour enhancement processing according to a contour enhancement processing method, wherein the contour enhancement processing method is selected from a plurality of contour enhancement processing methods by a user operation, the plurality of contour enhancement processing methods are respectively associated with different parameters, and the edge component correction unit corrects the edge components with reference to the parameters associated with the selected contour enhancement processing method.

7. The endoscope processor for an electronic endoscope according to claim 1 or 2, wherein, The processor further includes a light source unit that can generate either first illumination light in a first wavelength band or second illumination light in a second wavelength band different from the first wavelength band as the illumination light for illuminating the biological tissue. The first illumination light and the second illumination light are respectively associated with different threshold setting data. The edge component correction unit corrects the edge components with reference to the threshold setting data associated with the illumination light generated by the light source unit among the first illumination light and the second illumination light.

8. The processor for an electronic endoscope according to claim 3, wherein, the processor further includes a light source unit that can generate either first illumination light in a first wavelength band or second illumination light in a second wavelength band different from the first wavelength band as the illumination light for illuminating the biological tissue. The first illumination light and the second illumination light are respectively associated with different parameters. The edge component correction unit corrects the edge components with reference to the parameters associated with the illumination light generated by the light source unit among the first illumination light and the second illumination light.

9. An endoscope system, comprising: the processor for an endoscope according to any one of claims 1 to 8; and an endoscope connected to the processor for an endoscope and including an imaging element for imaging the biological tissue.

Images