JP6427356B2 - Image signal generating apparatus and electronic endoscope system - Google Patents

Description

  The present invention relates to an image signal generating device and an electronic endoscope system for generating an image signal of a living tissue.

  Electronic endoscope systems for observing a patient's body cavity are known. In this type of electronic endoscope system, it is possible to image a body cavity to which natural light does not reach by guiding the irradiation light emitted from the light source lamp into the body cavity and irradiating the body cavity.

  The living tissue in the body cavity is covered with mucous membrane and is glossy. Therefore, when the irradiation light is specularly reflected and is incident on the light receiving surface of the imaging device, the biological tissue located in the specular reflection region may be blown out and may not be observed as a highlight. In view of this problem, a specific configuration of an electronic endoscope system for removing this type of highlight is described, for example, in Patent Document 1 and Patent Document 2.

  The electronic endoscope system described in Patent Document 1 removes a highlight portion of a processing target image by combining a plurality of images in which the same object is captured. Specifically, the electronic endoscope system described in Patent Document 1 uses the information of the portion corresponding to the same living tissue of the other images as the living tissue lost as the highlighted portion in the processing target image. Restore by compensation processing.

  The electronic endoscope system described in Patent Document 2 includes a pair of light sources, and a polarizing plate is disposed in front of one of the light sources. The electronic endoscope system described in Patent Document 2 alternately illuminates a body cavity with irradiation light in a linearly polarized state and irradiation light in a non-polarized state by alternately turning on a pair of light sources to capture an image. The image in the body cavity irradiated with the irradiation light in the non-polarization state becomes an image including the highlight part (an image consisting of both the surface reflection component and the internal reflection component), but is irradiated by the irradiation light in the linear polarization state The image in the body cavity is an image without a highlight portion (an image consisting of only an internal reflection component without a surface reflection component).

JP-A-5-108819 JP, 2014-18439, A

  In the electronic endoscope system described in Patent Document 1, the problem of high operation cost is pointed out because the highlight portion is restored using a large number of images. Moreover, the problem that the precision which removes a highlight part is low is also pointed out.

  In the electronic endoscope system described in Patent Document 2, it is necessary to dispose a polarizing plate at the tip of an electronic scope where reduction in diameter is strongly required. In addition, it is necessary to suppress the deterioration of color reproducibility due to the polarizing plate. In order to suppress the deterioration of the color reproducibility due to the polarizing plate, the electronic endoscope system described in Patent Document 2 has limitations in the wavelength characteristics of usable irradiation light. That is, the available light sources are limited, and the choice of light sources is limited.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to reduce the calculation cost while accurately removing surface reflection components such as highlight portions, and the tip of an electronic scope. It is an object of the present invention to provide an electronic endoscope system which is advantageous for reducing the diameter of the optical system and which does not need to take into consideration deterioration of color reproducibility due to a polarizing plate, and an image signal generating device constituting the electronic endoscope system.

  An image signal generation apparatus according to an embodiment of the present invention is an illumination including at least a partial band of light other than narrow band light and peak light having a peak intensity at a specific wavelength for emphasizing a specific internal structure of living tissue. Color signal extraction means for extracting a color signal corresponding to a specific wavelength from among image signals of the living body tissue imaged by the predetermined imaging device, the living body tissue being irradiated with light; Means for generating an image signal of the surface reflection component of the living tissue based on the selected color signal, and subtracting the image signal of the surface reflection component from the image signal of the living tissue to obtain internal reflection of the living tissue And second image signal generating means for generating an image signal of the component.

  Thus, by using a color signal corresponding to a specific wavelength for emphasizing a specific internal structure among the image signals of the biological tissue irradiated with the irradiation light including the narrow band light described above, the surface of the biological tissue is obtained. Since the image signal representing the reflection component with high accuracy is generated, the image signal of the internal reflection component in which the surface reflection component is accurately removed is obtained while the calculation cost is suppressed. In addition, since it is not necessary to dispose a polarizing plate at the tip of the electronic scope where reduction in diameter is strongly required, it is advantageous for reducing the diameter of the electronic scope and it is not necessary to consider deterioration in color reproducibility by the polarizing plate. .

  The first image signal generation means calculates a reference value of a color signal corresponding to a specific wavelength, subtracts the pixel value of the color signal at each pixel by the reference value, and generates a surface based on the color signal subtracted by the reference value. The image signal of the reflection component may be generated.

  The reference value calculated by the first image signal generating means is, for example, an average pixel value, a median of pixel values, or a weighted average of maximum and minimum values for a color signal corresponding to a specific wavelength.

  The first image signal generation means may be configured to calculate the reference value excluding the color signals corresponding to the specific wavelength whose pixel values do not fall within the predetermined range.

  The specific wavelength is, for example, a wavelength at which the absorptivity of hemoglobin is high.

  The irradiation light is, for example, three narrow band light having peak intensities in respective color components of R (Red) component, G (Green) component, and B (Blue) component.

  The image signal generating apparatus according to the embodiment of the present invention applies demosaicing processing to an image signal of a living tissue imaged by an imaging device to provide each pixel with a signal of each color component of an R signal, a G signal, and a B signal. It is good also as composition provided with a demosaicing processing means. In this case, the first image signal generation means calculates the reference value of the B signal, subtracts the pixel value of the B signal in each pixel by the reference value, and calculates the pixel values of the R signal and the G signal in each pixel as a reference value. The image signal of the surface reflection component is generated by substituting the same pixel value as that of the B signal subtracted in the above. The second image signal generation means generates an image signal of the internal reflection component by subtracting the image signal of the surface reflection component from the image signal of the demosaiced biological tissue.

  The image signal generation apparatus according to the embodiment of the present invention may be configured to include a composite image generation unit that generates a composite image in which the image signal of the surface reflection component and the image signal of the internal reflection component are combined by a predetermined weighting coefficient.

  The electronic endoscope system according to an embodiment of the present invention includes narrowband light having a peak intensity at a specific wavelength and light of at least a partial band other than narrowband light for emphasizing a specific internal structure of living tissue. An irradiation device that emits irradiation light to irradiate living tissue, an imaging device that images living tissue irradiated by the irradiation light to generate an image signal of the living tissue, and an image signal of the living tissue generated by the imaging device And the image signal generation apparatus described above.

  According to the embodiment of the present invention, surface reflection components such as highlight portions can be accurately removed while suppressing the calculation cost, and it is advantageous for reducing the diameter of the tip of the electronic scope and the color by the polarizing plate There is provided an electronic endoscope system and an image signal generating apparatus constituting the electronic endoscope system, which do not need to consider deterioration of reproducibility.

It is a block diagram showing composition of an electronic endoscope system of an embodiment of the present invention. It is the front view which looked at the rotation filter part with which the processor of embodiment of this invention is seen from the condensing lens side. It is a figure which shows the example of a spectrum characteristic of the optical filter with which the processor of embodiment of this invention was equipped. It is a figure which shows the special image generation flow by the special image processing circuit with which the processor of embodiment of this invention is equipped. It is a figure which shows typically the mode of the narrow-band light of B component when special light is irradiated to a biological tissue.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, an electronic endoscope system will be described by way of example as an embodiment of the present invention.

  FIG. 1 is a block diagram showing the configuration of the electronic endoscope system 1 of the present embodiment. As shown in FIG. 1, the electronic endoscope system 1 includes an electronic scope 100, a processor 200 and a monitor 300.

  The processor 200 comprises a system controller 202 and a timing controller 204. The system controller 202 executes various programs stored in the memory 212 and controls the entire electronic endoscope system 1 in an integrated manner. In addition, the system controller 202 is connected to the operation panel 218. The system controller 202 changes each operation of the electronic endoscope system 1 and parameters for each operation in accordance with an instruction from the operator input from the operation panel 218. The input instruction by the operator includes, for example, an instruction to switch the operation mode of the electronic endoscope system 1. In the present embodiment, there are a normal mode and a special mode as operation modes. The timing controller 204 outputs clock pulses for adjusting the timing of operation of each unit to each circuit in the electronic endoscope system 1.

  The lamp 208 emits the irradiation light L after being started by the lamp power igniter 206. The lamp 208 is, for example, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp. The irradiation light L is light (or light including at least a visible light region) having a spectrum extending mainly from a visible light region to an infrared light region which is invisible. The irradiation light L emitted from the lamp 208 is incident on the rotary filter unit 260.

  FIG. 2 is a front view of the rotary filter unit 260 as viewed from the condenser lens 210 side. The rotary filter unit 260 includes a rotary turret 261, a DC motor 262, a driver 263 and a photo interrupter 264. As shown in FIG. 2, in the rotary turret 261, a filter Fn for normal light (white light) and a filter Fs for special light are arranged side by side. Each optical filter has a fan shape that extends over an angle range of about 180 °.

  FIGS. 3A and 3B are graphs showing spectral characteristics of the normal light filter Fn and the special light filter Fs, respectively. In each of FIGS. 3 (a) and 3 (b), the vertical axis represents transmittance (no unit for normalization), and the horizontal axis represents wavelength (unit: nm).

  The normal light filter Fn is a light reduction filter that reduces the light beam L. Therefore, as shown in FIG. 3A, the spectral characteristics of the normal light filter Fn are flat. The normal light filter Fn may be replaced by a simple opening (without an optical filter) or a slit (without an optical filter) that also serves as a stop function.

  As shown in FIG. 3B, the special light filter Fs has a narrow half bandwidth having a transmission peak wavelength in each color component of R (Red) component, G (Green) component, and B (Blue) component. It is a band pass optical filter. The transmission peak wavelength in the B component is a wavelength (near 415 nm) at which the absorptivity by hemoglobin is high. Narrow band light having a peak wavelength around 415 nm via the special light filter Fs is suitable for capturing a spectral image of a specific internal structure (blood vessel structure) of a living tissue.

  The driver 263 drives the DC motor 262 under the control of the system controller 202. The rotary filter unit 260 rotates the rotary turret 261 by the DC motor 262 to generate one of two types of irradiation light (normal light and special light) having different spectra from the irradiation light L incident from the lamp 208. Take out.

  Specifically, when the driver 263 is switched to the normal mode, the rotary turret 261 is rotated to a position where the filter for normal light Fn is inserted into the light path of the illumination light L, and switching to the special mode is not performed. The rotary turret 261 is stopped at this position. When the driver 263 is switched to the special mode, the rotary turret 261 is rotated to a position where the special light filter Fs is inserted in the optical path of the illumination light L, and the rotary turret is used unless switched to the normal mode. The H. 261 is stopped at this position. The rotational position and rotational phase of the rotary turret 261 are controlled by detecting an opening (not shown) formed in the vicinity of the outer periphery of the rotary turret 261 by the photointerrupter 264.

[Operation in normal mode]
The operation of the electronic endoscope system 1 in the normal mode will be described. In the normal mode, the normal light filter Fn is inserted in the light path of the illumination light L. Therefore, the irradiation light L emitted from the lamp 208 passes through the normal light filter Fn and is incident on the condensing lens 210. Hereinafter, for convenience of the description, the irradiation light L after passing through the normal light filter Fn will be referred to as “normal light Ln”. The ordinary light Ln incident on the condensing lens 210 is condensed on the incident end face of a light carrying bundle (LCB) 102 and is incident on the LCB 102.

  The normal light Ln propagates in the LCB 102 and is emitted from the emission end face of the LCB 102 disposed at the tip of the electronic scope 100, and illuminates the subject (living tissue in the body cavity) through the light distribution lens 104. The return light from the living tissue irradiated with the normal light Ln forms an optical image on the light receiving surface of the solid-state imaging device 108 via the objective lens 106.

  The solid-state imaging device 108 is a single-plate color charge coupled device (CCD) image sensor having a Bayer-type pixel arrangement. The solid-state imaging device 108 accumulates the optical image (return light from the living tissue irradiated with the normal light Ln) formed by each pixel on the light receiving surface as the electric charge according to the light amount, Generate and output an image signal. Hereinafter, an image signal of each pixel (each pixel address) sequentially output from the solid-state imaging device 108 is referred to as a “pixel signal”. The solid-state imaging device 108 is not limited to the CCD image sensor, and may be replaced by a complementary metal oxide semiconductor (CMOS) image sensor or another type of imaging device. The solid-state imaging device 108 may also be equipped with a complementary color filter.

  In the connection portion of the electronic scope 100, a driver signal processing circuit 112 is provided. The pixel signal of the living tissue irradiated with the normal light Ln is input to the driver signal processing circuit 112 from the solid-state imaging device 108 at a frame period. The driver signal processing circuit 112 outputs the pixel signal input from the solid-state imaging device 108 to the pre-stage signal processing circuit 220 of the processor 200. In the following description, “frame” may be replaced with “field”. In the present embodiment, the frame period and the field period are 1/30 seconds and 1/60 seconds, respectively.

  The driver signal processing circuit 112 also accesses the memory 114 to read out the unique information of the electronic scope 100. The unique information of the electronic scope 100 recorded in the memory 114 includes, for example, the number of pixels and sensitivity of the solid-state imaging device 108, an operable frame rate, and a model number. The driver signal processing circuit 112 outputs the unique information read from the memory 114 to the system controller 202.

  The system controller 202 performs various operations based on the unique information of the electronic scope 100 to generate a control signal. The system controller 202 controls the operation and timing of various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed using the generated control signal.

  The timing controller 204 supplies clock pulses to the driver signal processing circuit 112 in accordance with timing control by the system controller 202. The driver signal processing circuit 112 drives and controls the solid-state imaging device 108 at timing synchronized with the frame rate of the image processed on the processor 200 side according to the clock pulse supplied from the timing controller 204.

  The pre-stage signal processing circuit 220 performs demosaicing on each of the R, G, and B pixel signals input from the driver signal processing circuit 112 in a frame cycle. Specifically, interpolation processing is performed on each pixel signal of R by G and B peripheral pixels, interpolation processing is performed on each pixel signal of G by R and B peripheral pixels, and R is performed on each pixel signal of B , G peripheral pixels are subjected to interpolation processing. As a result, all pixel signals having information of only one color component are converted into pixel signals having information of three color components (R signal, G signal and B signal).

  The pre-stage signal processing circuit 220 performs predetermined signal processing such as matrix operation, white balance adjustment processing, and gamma correction processing on the pixel signal after the demosaicing processing, and outputs the processed signal to the special image processing circuit 230.

  The special image processing circuit 230 passes the pixel signal input from the front stage signal processing circuit 220 through to the rear stage signal processing circuit 240.

  The post-stage signal processing circuit 240 performs predetermined signal processing on the pixel signal input from the special image processing circuit 230 to generate screen data for monitor display, and the generated screen data for monitor display has a predetermined video format. Convert to a signal. The converted video format signal is output to the monitor 300. Thereby, the color image of the living tissue is displayed on the display screen of the monitor 300.

[Operation in special mode]
Next, the operation of the electronic endoscope system 1 in the special mode will be described. In the special mode, the special light filter Fs is inserted into the light path of the illumination light L. Therefore, the irradiation light L emitted from the lamp 208 passes through the special light filter Fs and is incident on the condenser lens 210. Hereinafter, for convenience of description, the irradiation light L after passing through the special light filter Fs will be referred to as “special light Ls”. The special light Ls incident on the condensing lens 210 is condensed on the incident end face of the LCB 102 and is incident on the LCB 102.

  The special light Ls propagates in the LCB 102 and is emitted from the emission end surface of the LCB 102, and irradiates a living tissue via the light distribution lens 104. The return light from the biological tissue irradiated with the special light Ls forms an optical image on the light receiving surface of the solid-state imaging device 108 via the objective lens 106.

  The solid-state imaging device 108 accumulates an optical image (returned light from the living tissue irradiated by the special light Ls) formed by each pixel on the light receiving surface as a charge corresponding to the light amount to obtain R, G, B Each pixel signal is generated and output.

  The pixel signal of the living tissue illuminated by the special light Ls is input to the driver signal processing circuit 112 from the solid-state imaging device 108 at a frame period. The driver signal processing circuit 112 outputs a pixel signal input from the solid-state imaging device 108 to the previous-stage signal processing circuit 220.

  The pre-stage signal processing circuit 220 performs predetermined image processing such as demosaicing processing, matrix operation, white balance adjustment processing, and gamma correction processing on pixel signals input from the driver signal processing circuit 112 in a frame cycle to perform special image processing. It outputs to the circuit 230.

  The special image processing circuit 230 executes the following special image processing flow using the pixel signal input from the front stage signal processing circuit 220 to generate a pixel signal of a special image, and outputs it to the rear stage signal processing circuit 240. The post-stage signal processing circuit 240 converts the pixel signal of the special image input from the special image processing circuit 230 into a predetermined video format signal and outputs it to the monitor 300. Thereby, the special image of the living tissue is displayed on the display screen of the monitor 300.

[Flow of Special Image Generation by Special Image Processing Circuit 230]
FIG. 4 shows a flow of special image processing by the special image processing circuit 230.

[S11 in FIG. 4 (insertion of the special light filter into the light path)]
In the main processing step S11, after switching to the special mode, the special light filter Fs is inserted into the light path of the illumination light L.

[S12 in FIG. 4 (input of pixel signal of current frame)]
In the main processing step S12, the pixel signal of the current frame (pixel signal having information of three color components (R signal, G signal and B signal)) is input from the previous stage signal processing circuit 220.

[S13 in FIG. 4 (selection of the target pixel)]
In the main processing step S13, one target pixel is selected from all the pixels in a predetermined order.

[S14 in FIG. 4 (pixel value determination of B signal)]
In the main processing step S14, it is determined whether or not the pixel value of the B signal falls within a predetermined range for the target pixel selected in the processing step S13 (selection of a target pixel). The B signal exceeding the upper limit value of the predetermined range and the B signal falling below the lower limit value are a highlight part and a shaded part, respectively, and information is lost. That is, in the main processing step S14, it is determined whether the B signal of the pixel of interest is a highlight portion and whether it is a shaded portion.

[S15 in FIG. 4 (addition of pixel values)]
This processing step S15 is executed when it is determined that the pixel value of the B signal of the target pixel falls within the predetermined range in processing step S14 (pixel value determination of the B signal) (S14: YES). In the main processing step S15, the pixel value of the B signal of the pixel of interest is added to the calculation addition value. Here, the calculation addition value is a value stored in the buffer 230A of the special image processing circuit 230, and the total value of the pixel values of the B signals determined to be within the predetermined range by the processing so far for the current frame. Indicates The calculation addition value is reset to zero at the start of execution of the special image processing flow for the next frame.

[S16 in FIG. 4 (determination of execution completion of processing for all pixels)]
When it is determined that the pixel value of the B signal of the target pixel does not fall within the predetermined range in the processing step S14 (pixel value determination of the B signal) in the main processing step S16 (S14: NO), or This is executed when the pixel value of the B signal of the pixel of interest is added to the calculation addition value in S15 (addition of pixel values). In the main processing step S16, it is determined whether or not the pixel value determination processing of the processing step S14 (pixel value determination of the B signal) has been performed on all the pixels of the current frame.

  If there are remaining pixels for which the pixel value determination process of the processing step S14 (pixel value determination of the B signal) has not been executed (S16: NO), this flow returns to the processing step S13 (selection of the target pixel) A pixel is selected, and pixel value determination processing in processing step S14 (pixel value determination of the B signal) is performed on the selected target pixel.

[S17 in FIG. 4 (calculation of reference value)]
The process step S17 is performed when it is determined that the pixel value determination process of the process step S14 (pixel value determination of the B signal) has been performed on all the pixels of the current frame (S16: YES). In the main processing step S17, the addition value for calculation (total value of pixel values of B signals falling within a predetermined range) stored in the buffer 230A is divided by the total number of pixels in which pixel values of B signals fall within the predetermined range. As a result, a predetermined reference value (average pixel value of the B signal falling within the predetermined range) is calculated.

[S18 in FIG. 4 (generation of pixel signal of surface reflection component)]
FIG. 5 schematically shows the state of narrow band light of the B component when special tissue Ls is irradiated to a living tissue. As shown in FIG. 5, when the special light Ls is irradiated to the living tissue, narrow band light of the B component is partially reflected by the surface of the living tissue (for example, mucous membrane etc.) and received by the solid-state imaging device 108 The light is received by the solid-state imaging device 108 after being partially scattered or absorbed in the living tissue. However, the narrow band light of the B component irradiated to the area without the mucous membrane is not substantially reflected on the surface of the living tissue, and after being partially scattered or absorbed in the living tissue, the solid-state imaging device 108 It is only received. Hereinafter, for convenience of explanation, a component that is reflected by the surface of the living tissue and received by the solid-state imaging device 108 is referred to as “surface reflection component”, and after being scattered or absorbed in the living tissue, received by the solid-state imaging device 108 Component is referred to as "internal reflection component".

  As described above, the B component received by each pixel of the solid-state imaging device 108 includes information of both the surface reflection component and the internal reflection component by using narrow band light having a peak wavelength around 415 nm, It can be roughly divided into those including information of only the internal reflection component. The surface reflection component is high in intensity because it is not absorbed by hemoglobin, but the internal reflection component is low in intensity because absorption by hemoglobin is dominant. Therefore, for the B component, a pixel including information on both the surface reflection component and the internal reflection component is distributed with a pixel value higher than the reference value (average pixel value) calculated in processing step S17 (calculation of reference value). The pixels including information of only the internal reflection component are distributed at pixel values lower than the reference value (average pixel value). In FIG. 5, the surface reflection component with high intensity is shown by a thick line, and the internal reflection component with low intensity is shown by a broken line, so that the intensity of the reflection component can be easily grasped visually.

  Therefore, in the present embodiment, a pixel whose pixel value of the B signal is higher than the reference value (average pixel value) is treated as a pixel including information of both the surface reflection component and the internal reflection component. Further, a pixel whose pixel value of the B signal is lower than the reference value (average pixel value) is treated as a pixel including information of only the internal reflection component.

  In the main processing step S18, the pixel value of the B signal is subtracted by the reference value (average pixel value) in each pixel of the current frame. The pixel values that become negative after subtraction are reset to zero. Then, in each pixel, the pixel value of the R signal and the G signal is replaced with the same pixel value as the B signal subtracted by the reference value, whereby the pixel signal of the surface reflection component (hereinafter referred to as “surface reflection pixel signal”) Note) is generated. As described above, in each pixel, the surface reflection pixel signal includes the R signal, the G signal, and the B signal of the same pixel value.

  Even after the reference value subtraction, the pixel having a positive pixel value is the information obtained by subtracting the information of the internal reflection component from the information including both the surface reflection component and the internal reflection component, that is, a pixel having information of only the surface reflection component It is considered. In addition, the pixel whose pixel value is zero or negative (hereinafter reset to zero) after subtraction of the reference value is obtained by subtracting the information of the internal reflection component from the information of the internal reflection component, that is, the information of the surface reflection component is also internal reflection. It is considered as a pixel that does not have component information.

  As described above, in the present processing step S18, subtraction processing of the B signal and replacement processing of the R signal and the G signal with the reference value (average pixel value) calculated in the processing step S17 (calculation of the reference value) are performed. Only the information (surface reflection pixel signal) of the surface reflection component is generated from the information in which the surface reflection component and the internal reflection component are mixed. Information on the surface reflection component (surface reflection) because pixels including information on both the surface reflection component and the internal reflection component and pixels including information on only the internal reflection component are accurately classified by the reference value (average pixel value) The pixel signal is accurately extracted.

[S19 in FIG. 4 (generation of pixel signal of internal reflection component)]
In the main processing step S19, processing is performed in processing step S18 (generation of a pixel signal of surface reflection component) from the pixel signal of the current frame (pixel signal having information (R signal, G signal and B signal) of three color components). The surface-reflected pixel signal is subtracted. That is, the information of the surface reflection component is subtracted from the information in which the surface reflection component and the internal reflection component are mixed. As a result, pixel signals of internal reflection components (hereinafter referred to as "internal reflection pixel signals") having information of three color components (R signal, G signal and B signal) are generated.

[S20 in FIG. 4 (determination of display mode)]
The operator can set the display mode of the special image to be displayed on the display screen of the monitor 300 by operating the operation panel 218. The display modes that can be set include, for example, a surface reflection image display mode, an internal reflection image display mode, and a composite image display mode. In the present processing step S20, the display mode of the currently set special image is determined.

[S21 in FIG. 4 (output of surface reflection pixel signal)]
This processing step S21 is executed when the display mode of the special image currently set in processing step S20 (determination of display mode) is determined to be the surface reflection image display mode (S20: surface reflection image display mode). Ru. In the main processing step S21, the surface reflection pixel signal generated in the processing step S18 (generation of the pixel signal of the surface reflection component) is output to the post-stage signal processing circuit 240. Thereby, the image of the surface reflection component of the living tissue (image of the mucous membrane mainly covering the living tissue) is displayed on the display screen of the monitor 300. Some diseases are associated with mucosal loss. An image of the surface reflection component of the living tissue is a judgment material for this type of disease.

[S22 in FIG. 4 (output of internal reflection pixel signal)]
This processing step S22 is executed when the display mode of the special image currently set in the processing step S20 (determination of display mode) is determined to be the internal reflection image display mode (S20: internal reflection image display mode). Ru. In the main processing step S22, the internal reflection pixel signal generated in the processing step S19 (generation of the pixel signal of the internal reflection component) is output to the post-stage signal processing circuit 240. Thereby, the image of the internal reflection component of the living tissue is displayed on the display screen of the monitor 300.

[S23 in FIG. 4 (generation and output of combined pixel signal)]
The process step S23 is executed when the display mode of the special image currently set in the process step S20 (determination of the display mode) is determined to be the composite image display mode (S20: composite image display mode). In the main processing step S23, the surface reflection pixel signal generated in the processing step S18 (generation of the pixel signal of the surface reflection component) and the internal reflection pixel generated in the processing step S19 (generation of the pixel signal of the internal reflection component) A composite pixel signal is generated by combining the signal with a predetermined weighting factor. The generated composite pixel signal is output to the post-stage signal processing circuit 240. Thereby, for example, a composite image in which the internal reflection component is intensified while weakening the surface reflection component of the living tissue is displayed on the display screen of the monitor 300. The weighting factor at the time of combining can be appropriately set and changed by the operation of the operation panel 218.

  The above is a description of an exemplary embodiment of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, contents obtained by appropriately combining the embodiments explicitly illustrated in the specification or the obvious embodiments are also included in the embodiments of the present application. For example, the reference value calculated in processing step S17 (calculation of reference value) in FIG. 4 is not limited to the average pixel value, but a predetermined range in processing step S14 in FIG. 4 (pixel value determination for B signal). It may be a median value of pixel values of the B signal falling within the range, or a weighted average value of the maximum value and the minimum value of the B signal falling within the predetermined range.

1 Electronic endoscope system 100 Electronic scope 102 LCB
DESCRIPTION OF SYMBOLS 104 Light distribution lens 106 Objective lens 108 Solid-state image sensor 112 Driver signal processing circuit 114 Memory 200 Processor 202 System controller 204 Timing controller 206 Lamp power igniter 208 Lamp 210 Condenser lens 212 Memory 218 Operation panel 220 Pre-stage signal processing circuit 230 Special image processing Circuit 230A Buffer 240 Post-stage signal processing circuit 260 Rotary filter section 261 Rotary turret Fn Filter for ordinary light Fs Filter for special light 262 DC motor 263 Driver 264 Photo interrupter

Claims (9)

A biological tissue irradiated with narrowband light having a peak intensity at a specific wavelength for emphasizing a specific internal structure of biological tissue and irradiation light including light of at least a part of the band other than the narrowband light, Color signal extraction means for extracting a color signal corresponding to the specific wavelength from image signals of a living tissue imaged by a predetermined imaging device;
First image signal generation means for generating an image signal of a surface reflection component of the living tissue based on the color signal extracted by the color signal extraction means;
Second image signal generating means for generating an image signal of an internal reflection component of the living tissue by subtracting the image signal of the surface reflection component from the image signal of the living tissue;
Equipped with
Image signal generator. The first image signal generating means
Calculating a reference value of a color signal corresponding to the specific wavelength;
At each pixel, the pixel value of the color signal is subtracted by the reference value,
Generating an image signal of the surface reflection component based on the color signal subtracted by the reference value;
The image signal generation device according to claim 1. The reference value is
An average pixel value, a median of pixel values, or a weighted average of maximum and minimum values for a color signal corresponding to the specific wavelength;
The image signal generation device according to claim 2. The first image signal generating means
The reference value is calculated excluding color signals corresponding to the specific wavelength whose pixel values do not fall within a predetermined range.
The image signal generation device according to claim 3. The specific wavelength is
It is a wavelength with high absorption rate by hemoglobin,
The image signal generation device according to any one of claims 1 to 4. The irradiation light is
Three narrow band lights having peak intensities in each color component of R (Red) component, G (Green) component, and B (Blue) component,
The image signal generation device according to any one of claims 1 to 5. The image signal of the living tissue imaged by the imaging device is subjected to a demosaicing process, thereby providing demosaicing means for giving each pixel a signal of each color component of R signal, G signal and B signal,
The first image signal generating means
Calculate the reference value of the B signal,
At each pixel, the pixel value of the B signal is subtracted by the reference value,
An image signal of the surface reflection component is generated by replacing pixel values of the R signal and G signal with pixel values identical to the B signal subtracted by the reference value in each pixel,
The second image signal generating means
An image signal of the internal reflection component is generated by subtracting the image signal of the surface reflection component from the image signal of the demosaiced biological tissue.
The image signal processing apparatus according to claim 6. And a composite image generation unit configured to generate a composite image obtained by combining the image signal of the surface reflection component and the image signal of the internal reflection component with a predetermined weighting coefficient.
The image signal generating device according to any one of claims 1 to 7. A narrow band light having a peak intensity at a specific wavelength for emphasizing a specific internal structure of a living tissue and an irradiation light including light of at least a part of a band other than the narrow band light are emitted to irradiate the living tissue An irradiation device,
An imaging device for imaging a living tissue irradiated by the irradiation light to generate an image signal of the living tissue;
The image signal generation device according to any one of claims 1 to 8, wherein an image signal of a living tissue generated by the imaging device is processed;
Equipped with
Electronic endoscope system.

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