JP2016067780A - Endoscope system, processor device, method for operating endoscope system, and method for operating processor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope system capable of displaying an image in which a blood vessel at specific depth is easily observed, and to provide a processor device, a method for operating an endoscope system, and a method for operating a processor device.SOLUTION: An endoscope system includes a light source for generating illumination light, an imaging sensor for imaging an observation object irradiated with illumination light, an image signal acquisition part for acquiring a B1 image signal corresponding to violet light V, and also acquiring a B2 image signal corresponding to blue light B, a setting part for setting the depth of a blood vessel to be observed, an image signal selection part 72 for select any image signal among the B1 image signal, the B2 image signal, by using the setting of the depth of the blood vessel, and a mixed image signal obtained by mixing the B1 image signal with the B2 image signal, and an image generation part 78 for generating an image obtained by allocating the image signal selected by the image signal selection part to a luminance channel.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an endoscope system, a processor device, an operation method of an endoscope system, and an operation method of a processor device that extract a blood vessel to be observed using an image signal obtained by imaging an observation object.

  In the medical field, diagnosis using an endoscope system including a light source device, an endoscope system, and a processor device is widely performed. In medical diagnosis using an endoscope system, an insertion portion of an endoscope is inserted into a subject, and illumination light is irradiated from the distal end portion to an observation target. Then, the observation target irradiated with the illumination light is imaged by the imaging sensor at the tip, and an image of the observation target is generated using the obtained image signal and displayed on the monitor.

  In addition, since the shape and distribution of blood vessels are important in diagnosis using an endoscope system, in recent years, endoscope systems that extract blood vessels by various methods are known. For example, endoscope systems that extract blood vessels by pattern matching are known (Patent Documents 1 and 2). In addition, as a method for extracting blood vessels from an image signal, a method using a Gabor filter, a neural network, or the like is also known (Non-Patent Document 1). In addition, by weighting each image obtained using blue narrow-band light and green narrow-band light, blood vessels (hereinafter referred to as superficial blood vessels) at a relatively shallow position under the mucous membrane called the superficial layer are extracted. An endoscope system that extracts blood vessels (hereinafter referred to as “medium-deep blood vessels”) located deep in the submucosa called the middle layer or the deep layer is also known (Patent Document 3).

Japanese Patent No. 05435746 JP 2013-255808 A Japanese Patent No. 5393525

An Automated Tracking Approach for Extraction of Retinal Vasculature in Fundus Images, A. Osareh et al., J Ophthalmic Vis Res 2010; 5 (1): 20-26

  In recent years, it has been found that not only the presence or absence of blood vessels but also information on blood vessels at a specific depth below the mucous membrane can be used to determine the degree of disease progression (such as the stage of cancer). For example, the density of blood vessels at a specific depth can be used to determine the degree of progression of superficial cancers in the digestive tract. To give a more specific example, in the case of Barrett's adenocarcinoma, which is a disease of the esophagus, in the process of progression from Barrett's esophagus to Barrett's adenocarcinoma, among the blood vessels near the mucosal surface (hereinafter referred to as surface blood vessels), A change in density of a blood vessel in a shallow position (hereinafter referred to as an extreme surface blood vessel) is large. For this reason, it is considered that the stage discrimination accuracy of Barrett's adenocarcinoma is improved if the extreme surface blood vessels can be highlighted and displayed, or if the blood vessel density of the extreme surface blood vessels can be calculated.

  On the other hand, in the method of extracting and enhancing blood vessels with a conventional endoscope system, the submucosal depth where the observable blood vessels exist is generally determined by the depth of illumination light irradiated when imaging the observation target. ing. For example, the superficial blood vessel can be observed by using light of a short wavelength band such as blue light or violet light as illumination light. However, the difference between the stages of Barrett's adenocarcinoma is the density of the superficial blood vessels. Even if the superficial blood vessels are included, all the blood vessels in the wide range of the superficial layer are superimposed in the depth direction as before. As a result, the discrimination accuracy of the stage of Barrett's adenocarcinoma is lowered.

  In addition, the endoscope system of Patent Document 3 can extract only one of a surface blood vessel and a middle deep blood vessel by weighting two types of images. This is because there is a great difference in position. With this method, it is not easy to extract a polar surface blood vessel from the surface blood vessels. Even if only the superficial blood vessels can be extracted from the superficial blood vessels by weighting the two types of images, the balance of the weights is extremely severe and there are individual differences in the observation target, so that the superficial blood vessels are stably It is difficult to extract only the superficial blood vessels from the inside.

  The present invention relates to an endoscope system, a processor device, a method for operating an endoscope system, and a processor capable of displaying an image in which a blood vessel in a specific depth direction range (hereinafter referred to as a specific depth) can be easily observed. The object is to provide a method of operating the device.

  The endoscope system of the present invention acquires a light source that generates illumination light, an imaging sensor that images an observation target irradiated with the illumination light, and a first image signal corresponding to the first illumination light among the illumination light. And the image signal acquisition part which acquires the 2nd image signal corresponding to the 2nd illumination light from which wavelength band differs from the 1st illumination light among illumination lights, The setting part which sets the depth of the blood vessel to observe An image for selecting one of the first image signal, the second image signal, or a mixed image signal obtained by mixing the first image signal and the second image signal using the setting of the depth of the blood vessel. A signal selection unit; and an image generation unit that generates an image in which the image signal selected by the image signal selection unit is assigned to a luminance channel.

  A calculation image signal generation unit configured to generate a calculation image signal using the first image signal and the second image signal; the image generation unit assigns the image signal selected by the image signal selection unit to a luminance channel; and It is preferable to generate an image in which the signal is assigned to two color difference channels.

  It is preferable that the calculation image signal generation unit changes the calculation image signal generation method according to the setting of the depth of the blood vessel.

  The image signal selection unit includes a mixed image signal generation unit that generates a mixed image signal when the mixed image signal is selected. The mixed image signal generation unit is configured to set the first image signal and the second image signal by setting the depth of the blood vessel. It is preferable to generate the mixed image signal by changing the mixing ratio of the image signals.

  A light source that controls the wavelength bands of the first illumination light and the second illumination light by setting the depth of the blood vessel, or controls the balance of the light amounts of the first illumination light and the second illumination light by setting the depth of the blood vessel. It is preferable to provide a control unit.

  It is preferable that an observation distance acquisition unit that acquires the observation distance of the observation target is provided, and the setting unit sets the depth of the blood vessel using the observation distance.

  It is preferable to provide an imaging optical system that forms an image of the observation target on the imaging sensor and has a variable imaging magnification, and the observation distance acquisition unit acquires the imaging magnification of the imaging optical system as the observation distance.

  It is preferable that the setting unit includes an input unit for inputting blood vessel depth settings.

  It is preferable that the endoscope includes a light source device having a light source, an endoscope having an image sensor, and a processor device having an image generation unit, and the input unit is provided in the endoscope.

  It is preferable that a light source device having a light source, an endoscope having an imaging sensor, and a processor device having an image generation unit are provided, and the input unit is provided in the processor device.

  It is preferable to include an alignment processing unit that corrects at least one of the first image signal and the second image signal and aligns the observation target represented by the first image signal and the observation target represented by the second image signal.

  It is preferable to include a brightness correction processing unit that corrects at least one of the first image signal and the second image signal and sets the ratio between the brightness of the first image signal and the brightness of the second image signal to a specific ratio.

  The processor device of the present invention is a processor device of an endoscope system having a light source that generates illumination light and an image sensor that images an observation target irradiated with the illumination light. An image signal acquisition unit for acquiring a corresponding first image signal and acquiring a second image signal corresponding to a second illumination light having a wavelength band different from that of the first illumination light among the illumination light; Using the setting unit for setting the depth and the setting of the blood vessel depth, the first image signal, the second image signal, or the mixed image signal obtained by mixing the first image signal and the second image signal An image signal selection unit that selects any one of the image signals; and an image generation unit that generates an image in which the image signal selected by the image signal selection unit is assigned to a luminance channel.

  The operation method of the endoscope system according to the present invention includes a step in which a light source generates illumination light, an imaging sensor images an observation target irradiated with the illumination light, and an image signal acquisition unit A step of acquiring a first image signal corresponding to the first illumination light and acquiring a second image signal corresponding to the second illumination light having a wavelength band different from that of the first illumination light among the illumination light and setting The step of setting the depth of the blood vessel to be observed, and the image signal selection unit using the setting of the depth of the blood vessel, the first image signal, the second image signal, or the first image signal and the first image signal. A step of selecting any one of the mixed image signals obtained by mixing the two image signals, a step of generating an image in which the image generation unit assigns the image signal selected by the image signal selection unit to the luminance channel, and Is provided.

According to an embodiment of the present invention, there is provided an operating method of a processor device, including: a light source that generates illumination light; and an imaging sensor that images an observation target irradiated with the illumination light. A first image signal corresponding to the first illumination light in the illumination light, and a second image signal corresponding to the second illumination light having a wavelength band different from that of the first illumination light in the illumination light. A step of acquiring, a step of setting a depth of a blood vessel to be observed by a setting unit;
The image signal selection unit uses the blood vessel depth setting to select one of the first image signal, the second image signal, or a mixed image signal obtained by mixing the first image signal and the second image signal. Selecting a signal, and an image generating unit generating an image in which the image signal selected by the image signal selecting unit is assigned to a luminance channel.

  ADVANTAGE OF THE INVENTION According to this invention, the endoscope system which can display the image which the blood vessel of specific depth can observe easily, a processor apparatus, the operating method of an endoscope system, and the operating method of a processor apparatus can be provided. .

It is an external view of an endoscope system. It is a block diagram which shows the function of an endoscope system. It is a graph which shows the spectrum of purple light, blue light, green light, and red light. It is a graph which shows the scattering coefficient of an observation object. It is a graph which shows the extinction coefficient of hemoglobin. It is a graph which shows the spectral characteristic of a color filter. It is a block diagram which shows the function of a special image process part. 3 is a graph schematically showing a relationship between a blood vessel depth and a blood vessel contrast. It is explanatory drawing which shows the production | generation method of the specific depth blood vessel emphasis image. It is a flowchart at the time of special observation mode. It is a schematic diagram of a B1 image signal. It is a schematic diagram of a B2 image signal. It is a schematic diagram of a calculation image signal. It is a schematic diagram of the calculation image signal after a resolution reduction process. It is a schematic diagram of a specific depth blood vessel emphasis image. It is explanatory drawing which shows the production | generation method of the specific depth blood vessel emphasis image of the modification. It is a block diagram of a special image processing unit of the second embodiment. It is a block diagram of the endoscope system of a 3rd embodiment. It is a block diagram of the endoscope system of a 4th embodiment. It is a block diagram of the special image processing part of the modification which uses a mode change switch for the setting of the depth of the blood vessel to observe. It is a block diagram which shows the cooperation relationship of a special image process part and a position alignment process part. It is the schematic of a capsule endoscope.

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

  In addition to the angle knob 12e, the operation unit 12b is provided with a mode switch 13a, a zoom operation unit 13b, a still image acquisition instruction unit (not shown), and the like. The mode change switch 13a is used for an observation mode change operation. The endoscope system 10 has a normal observation mode and a special observation mode as observation modes. In the normal observation mode, an image having a natural color (hereinafter referred to as a normal image) obtained by imaging an observation target using white light as illumination light is displayed on the monitor 18. In the special observation mode, a blood vessel at a specific depth is extracted from the blood vessels included in the observation target using an image signal obtained by imaging the observation target, and is highlighted. In the endoscope system 10, as a special observation mode, a superficial blood vessel highlighting display mode for extracting and displaying a superficial blood vessel located at a relatively deep position in the mucosal surface layer, and a polar superficial blood vessel are extracted and highlighted in the special observation mode. A polar surface blood vessel highlighting display mode is further provided, and which is executed when the mode is switched to the special observation mode by operating the mode switching switch 13a is determined by setting.

  The processor device 16 is electrically connected to the monitor 18 and the console 19. The monitor 18 outputs and displays an image to be observed, information attached to the image to be observed, and the like. The console 19 is a user interface that receives an input operation such as function setting, and functions as an input unit for setting the depth of the blood vessel to be observed by the setting unit 71 (see FIG. 2). In the present embodiment, in the setting menu displayed on the monitor 18, “surface blood vessel” and “polar surface blood vessel” can be selected as the depth setting of the blood vessel to be observed. The processor device 16 may be connected to an external recording unit (not shown) for recording images and image information.

  As shown in FIG. 2, the light source device 14 includes a light source 20 and a light source control unit 22 that controls the light source 20. The light source 20 includes, for example, a plurality of semiconductor light sources, and these are turned on or off, and when they are turned on, the amount of light emitted from each semiconductor light source is controlled to generate illumination light that irradiates the observation target. In the present embodiment, the light source 20 includes a V-LED (Violet Light Emitting Diode) 23a, a B-LED (Blue Light Emitting Diode) 23b, a G-LED (Green Light Emitting Diode) 23c, and an R-LED (Red Light Emitting Diode). Diode) 23d has four-color LEDs. As shown in FIG. 3, the V-LED 23a is a violet light source that emits violet light V having a center wavelength of 405 nm and a wavelength band of 380 to 420 nm. The B-LED 23b is a blue semiconductor light source that emits blue light B having a center wavelength of 460 nm and a wavelength band of 420 to 500 nm. The G-LED 23c is a green semiconductor light source that emits green light G having a wavelength band ranging from 480 to 600 nm. The R-LED 23d is a red semiconductor light source that emits red light R with a center wavelength of 620 to 630 nm and a wavelength band of 600 to 650 nm. The center wavelengths of the V-LED 23a and the B-LED 23b have a width of about ± 5 nm to ± 10 nm.

  The lighting and extinguishing of each of these LEDs 23a to 23d, the light emission amount at the time of lighting, and the like can be controlled by the light source control unit 22 by inputting an independent control signal. In the normal observation mode, the light source control unit 22 turns on all the V-LEDs 23a, B-LEDs 23b, G-LEDs 23c, and R-LEDs 23d. For this reason, in the normal observation mode, white light including purple light V, blue light B, green light G, and red light R is used as illumination light. On the other hand, in the special observation mode, the light source control unit 22 turns on only the V-LED 23a, turns off the other LEDs such as the B-LED 23b, and turns off the V-LED 23a and turns off the B-LED 23b. The light source 20 is controlled by the second light emission pattern that is turned on and turns off other LEDs such as the V-LED 23a. That is, in the special observation mode, the violet light V and the blue light B are sequentially generated and irradiated on the observation target. Therefore, the purple light V is the first illumination light, and the blue light B is the second illumination light having a wavelength band different from that of the first illumination light.

  In the present embodiment, as described above, the violet light V emitted from the V-LED 23a and the blue light B emitted from the B-LED 23a are used as they are as the first illumination light and the second illumination light in the special observation mode. However, it is preferable that the purple light V and the blue light B are further used as illumination light in the special observation mode after the wavelength band is further restricted by providing the light source 20 with an optical filter or the like that restricts the wavelength band.

This is because when the first illumination light and the second illumination light are light in two wavelength bands having different scattering coefficients of the object to be observed and having substantially the same absorption coefficient of hemoglobin, blood vessels of a specific depth are extracted. This is because it can be extracted particularly clearly. For example, the scattering coefficient of the observation object in the wavelength band of each illumination light is related to the depth of the observation object, that is, the submucosal depth of the blood vessel that can be observed in the wavelength band. On the other hand, the extinction coefficient of hemoglobin is related to the contrast of blood vessels that can be observed with each illumination light. Therefore, the condition that the scattering coefficient of the observation target required for the first illumination light and the second illumination light used in the special observation mode is different and the absorption coefficient of hemoglobin is almost equal is that the observable blood vessel has a deep submucosal depth. It is a condition that light of two wavelength bands that can be observed with the same contrast can be selected and used for blood vessels with different depths and submucosal depths. Depending on the characteristics (center wavelength) of the LED used for the light source 20, the above conditions may not be completely satisfied. In such a case, at least within the range where the scattering coefficient of the observation target is different, as much as possible. Light in two wavelength bands with close hemoglobin absorption coefficients may be used as the first illumination light and the second illumination light. If the first illumination light is light in a shorter wavelength band than the second illumination light, the scattering coefficient of the observation object is different from the ratio of the scattering coefficient of the second illumination light to the scattering coefficient of the first illumination light. Is 0.8 or less. Further, the difference in the scattering coefficient between the first illumination light and the second illumination light is preferably 70 cm ⁻¹ or more.

  In the purple light V and the blue light B used as illumination light in the special observation mode, as shown in FIG. 4, the ratio of the scattering coefficient of the blue light B to the scattering coefficient of the purple light V is 0.75, which is shown in FIG. Thus, the extinction coefficient of hemoglobin (the extinction coefficient of oxidized hemoglobin: the extinction coefficient of reduced hemoglobin = 3: 7) is approximately the same.

  The light of each color emitted from each of the LEDs 23a to 23d is incident on a light guide 41 inserted into the insertion portion 12a via an optical path coupling portion (not shown) formed by a mirror, a lens, or the like. The light guide 41 is built in the endoscope 12 and the universal cord (a cord connecting the endoscope 12, the light source device 14, and the processor device 16). The light guide 41 propagates the illumination light generated by the light source 20 to the distal end portion 12 d of the endoscope 12.

  The distal end portion 12d of the endoscope 12 is provided with an illumination optical system 30a and an imaging optical system 30b. The illumination optical system 30 a has an illumination lens 45, and the illumination light propagated by the light guide 41 is irradiated to the observation object via the illumination lens 45. The imaging optical system 30 b includes an objective lens 46, a zoom lens 47, and an imaging sensor 48. Various types of light such as reflected light, scattered light, and fluorescence from the observation target due to the irradiation of the illumination light enter the image sensor 48 via the objective lens 46 and the zoom lens 47. As a result, an image to be observed is formed on the image sensor 48. The zoom lens 47 is freely moved between the tele end and the wide end by operating the zoom operation unit 13b, and enlarges or reduces the reflected image of the observation target formed on the image sensor 48. That is, the imaging optical system 30b forms an image of the observation target on the imaging sensor 48, and the imaging magnification is variable.

  The imaging sensor 48 is a color imaging sensor that images an observation target irradiated with illumination light. Each pixel of the image sensor 48 is provided with any of an R (red) color filter, a G (green) color filter, and a B (blue) color filter shown in FIG. Therefore, the imaging sensor 48 receives purple to blue light at the B pixel (blue pixel) provided with the B color filter, and receives green light at the G pixel (green pixel) provided with the G color filter. The red light is received by the R pixel (red pixel) provided with the R color filter. Then, RGB color image signals are output from each color pixel. In the special observation mode, when the light emission pattern of the light source 20 is the first light emission pattern, the purple light V is used as the illumination light. Therefore, the imaging sensor 48 images the observation target irradiated with the purple light V, and purple. A first image signal corresponding to the light V (hereinafter referred to as a B1 image signal) is output from the B pixel. When the light emission pattern of the light source 20 is the second light emission pattern, since the blue light B is used as illumination light, the imaging sensor 48 uses a second image signal (hereinafter referred to as a B2 image signal) corresponding to the blue light B. ) Is output from the B pixel.

  As the image sensor 48, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor can be used. Further, instead of the primary color imaging sensor 48, a complementary color imaging sensor including complementary color filters of C (cyan), M (magenta), Y (yellow), and G (green) may be used. When the complementary color image sensor is used, CMYG four-color image signals are output. By converting the CMYG four-color image signals into RGB three-color image signals by complementary color-primary color conversion, An RGB image signal similar to that of the image sensor 48 can be obtained. Further, instead of the imaging sensor 48, a monochrome sensor without a color filter may be used.

  The CDS / AGC circuit 51 performs correlated double sampling (CDS) and automatic gain control (AGC) on the analog image signal obtained from the image sensor 48. The image signal that has passed through the CDS / AGC circuit 51 is converted into a digital image signal by an A / D (Analog to Digital) converter 52. The digital image signal after A / D conversion is input to the processor device 16.

  The processor device 16 includes an image signal acquisition unit 53, a DSP (Digital Signal Processor) 56, a noise removal unit 58, an image processing switching unit 61, a normal image processing unit 66, a special image processing unit 67, and a video signal. And a generation unit 68. The image signal acquisition unit 53 acquires a digital image signal from the imaging sensor 48 via the CDS / AGC circuit 51 and the A / D converter 52.

  The DSP 56 performs various signal processing such as defect correction processing, offset processing, gain correction processing, linear matrix processing, gamma conversion processing, and demosaicing processing on the acquired image signal. In the defect correction process, the signal of the defective pixel of the image sensor 48 is corrected. In the offset process, the dark current component is removed from the image signal subjected to the defect correction process, and an accurate zero level is set. In the gain correction process, the signal level is adjusted by multiplying the image signal after the offset process by a specific gain.

  The image signal after gain correction processing is subjected to linear matrix processing for improving color reproducibility. After that, brightness and saturation are adjusted by gamma conversion processing. The image signal after the gamma conversion processing is subjected to demosaic processing (also referred to as isotropic processing or synchronization processing), and a signal of a color that is insufficient at each pixel is generated by interpolation. By this demosaic processing, all the pixels have RGB signals. The noise removal unit 58 removes noise by performing noise removal processing (for example, using a moving average method, a median filter method, or the like) on the image signal that has been demosaiced by the DSP 56. The image signal from which the noise has been removed is transmitted to the image processing switching unit 61. When the normal observation mode is set by the operation of the mode switch 13a, the image processing switching unit 61 transmits the received image signal to the normal image processing unit 66, and when the special observation mode is set, The received image signal is transmitted to the special image processing unit 67.

  The normal image processing unit 66 operates when the normal observation mode is set, and performs a color conversion process, a color enhancement process, and a structure enhancement process on the received image signal to generate a normal image signal. In color conversion processing, color conversion processing is performed on RGB image signals by 3 × 3 matrix processing, gradation conversion processing, three-dimensional LUT (look-up table) processing, and the like. The color enhancement process is performed on the image signal that has been subjected to the color conversion process. The structure enhancement process is a process for enhancing a structure to be observed such as a surface blood vessel or a pit pattern, and is performed on the image signal after the color enhancement process. As described above, a color image using a normal image signal that has been subjected to various types of image processing up to the structure enhancement processing is a normal image.

  The special image processing unit 67 is an image processing unit that operates when the special observation mode is set, and uses a B1 image signal corresponding to the purple light V and a B2 image signal corresponding to the blue light B. A blood vessel having a specific depth is extracted, and an image representing the extracted blood vessel with respect to other blood vessels by color difference is generated for display. Specifically, the special image processing unit 67 selects either the B1 image signal or the B2 image signal, and generates an image in which the selected image signal is assigned to the luminance channel.

  The special image processing unit 67 receives setting information indicating the depth of the blood vessel to be observed from the setting unit 71 that sets the depth of the blood vessel to be observed. Then, the special image processing unit 67 selects an image signal to be assigned to the luminance channel when generating an image for display using the setting information, that is, using the setting of the depth of the blood vessel to be observed. In the case of the present embodiment, the setting information input from the setting unit 71 is either “surface blood vessel” or “polar surface blood vessel”. For this reason, when the setting of the depth of the blood vessel to be observed is “surface blood vessel”, the special image processing unit 67 assigns the B2 image signal to the luminance channel and generates a display image. On the other hand, when the setting of the depth of the blood vessel to be observed is “polar surface blood vessel”, the special image processing unit 67 assigns the B1 image signal to the luminance channel and generates a display image. When a display image having an RGB channel is generated and the depth of the blood vessel to be observed is “surface blood vessel”, the B2 image signal is assigned to the G channel (green channel), and the RGB channel is set. When the depth of the blood vessel to be observed is “polar surface blood vessel”, the B1 image signal is assigned to the G channel.

  In addition, the B1 image signal and the B2 image signal input to the special image processing unit 67 are input via the alignment processing unit 62 and the brightness correction processing unit 63.

  The alignment processing unit 62 aligns the observation target represented by the sequentially acquired B1 image signal and the observation target represented by the B2 image signal. The alignment processing unit 62 corrects at least one of the B1 image signal and the B2 image signal.

  The brightness correction processing unit 63 has at least one of the B1 image signal and the B2 image signal so that the brightness of the B1 image signal and the B2 image signal aligned by the alignment processing unit 62 has a specific ratio. Correct the brightness. Specifically, since the light quantity ratio between the purple light V of the first light emission pattern and the blue light B of the second light emission pattern is known, the purple light V and the blue light B having the same light quantity are respectively obtained using these light quantity ratios. Gain correction is performed so that the brightness of the B1 image signal matches the brightness of the B2 image signal so that the brightness obtained when the observation object is irradiated is obtained. The brightness of the image signal is, for example, an average value of all the pixel values (or another statistical value such as a total value or an intermediate value), and generally corresponds to the brightness of the mucous membrane to be observed.

  As illustrated in FIG. 7, the special image processing unit 67 includes an image signal selection unit 72, a calculation image signal generation unit 76, a resolution reduction processing unit 77, and an image generation unit 78.

  Setting information indicating the depth of the blood vessel to be observed is input from the setting unit 71 to the image signal selection unit 72. The image signal selection unit 72 selects an image signal to be assigned to the luminance channel when the image generation unit 78 generates an image for display using the input setting information (that is, setting of the depth of the blood vessel to be observed). To do. In the case of this embodiment, since the setting information is one of two values “surface blood vessel” or “polar surface blood vessel”, the luminance channel is set from either the corresponding B1 image signal or B2 image signal. Select the image signal to be assigned. More specifically, when the setting information is “surface blood vessel”, the image signal selection unit 72 selects the B2 image signal, and when the setting information is “polar surface blood vessel”, the B1 image signal is selected.

  The calculation image signal generation unit 76 performs calculation using the B1 image signal and the B2 image signal that have been subjected to the alignment process and the brightness correction process, and generates a calculation image signal. Specifically, the difference or ratio between the B1 image signal and the B2 image signal is calculated. In the present embodiment, the calculation image signal generation unit 76 logarithmically converts the B1 image signal and the B2 image signal, and generates a calculation image signal ΔB by generating a difference between the B1 image signal and the B2 image signal after logarithmic conversion. To do. When the B1 image signal and the B2 image signal are used as they are without logarithmic conversion, a calculated image signal is generated by calculating the ratio of the B1 image signal and the B2 image signal for each pixel. The B1 image signal and the B2 image signal each have a pixel value proportional to the amount of received light. However, when logarithmic conversion is performed, the pixel value is proportional to the density. A stable calculation result can be obtained regardless of the illuminance of light.

  The calculation image signal generation unit 76 receives the setting information from the setting unit 71 and changes the generation method of the calculation image signal according to the setting of the depth of the blood vessel to be observed. Specifically, when the depth of the blood vessel to be observed is “surface blood vessel”, the operation image signal ΔB is generated by subtracting the B2 image signal from the B1 image signal after logarithmic conversion. On the other hand, when the setting of the blood vessel depth to be observed is “polar surface blood vessel”, the calculation image signal ΔB is generated by subtracting the B1 image signal from the B2 image signal after logarithmic conversion.

  Calculation of the calculated image signal ΔB as described above corresponds to extracting a blood vessel at a specific depth below the mucous membrane. For example, as shown in FIG. 8, when the purple light V and the blue light B are used as illumination light, the surface blood vessels (blood vessels in the entire range of the depth As and the depth Ad) can be observed. Since the violet light V has a shorter wavelength than the blue light B, the depth of penetration to the observation object is small, and only the blood vessel located at a shallow position As below the mucous membrane can be projected relative to the blue light B. The contrast of the blood vessel at the shallow position As (ratio of the amount of reflected light from the surrounding mucous membrane to the amount of reflected light from the blood vessel) is larger than when blue light B is used. On the other hand, since the wavelength of the blue light B is longer than that of the violet light V, the depth of penetration of the blue light B is large, and instead of being able to project a blood vessel at a deep position Ad below the mucosa relative to the violet light V, In addition, the contrast of the blood vessel at the shallow position As is smaller than when purple light V is used. For this reason, if the B1 image signal corresponding to the purple light V is subtracted from the B2 image signal corresponding to the blue light B, the pixel value of the pixel representing the extreme superficial blood vessel at the shallow position As, particularly under the mucous membrane, is emphasized. The pixel value of the pixel representing the superficial blood vessel at a position Ad deeper than the extreme superficial blood vessel becomes a small value (black). On the contrary, if the B2 image signal corresponding to the blue light B is subtracted from the B1 image signal corresponding to the purple light V, the pixel value of the pixel representing the extreme surface blood vessel at the shallow position As is small (black). Thus, the pixel value of the superficial blood vessel in the position Ad deeper than the extreme superficial blood vessel is emphasized and becomes a large value (white).

  The resolution reduction processing unit 77 is a so-called low-pass filter (hereinafter referred to as LPF), and lowers the resolution of the calculated image signal ΔB generated by the calculated image signal generation unit 76. The strength of the resolution reduction processing applied to the calculation image signal ΔB by the resolution reduction processing unit 77 is determined by the cutoff frequency of the LPF. The cut-off frequency of the LPF is set in advance, and at least lower than the resolution of the original calculation image signal ΔB.

  The image generation unit 78 generates an image having a plurality of output channels by using either the B1 image signal or the B2 image signal received by the special image processing unit 67 and the operation image signal ΔB having a reduced resolution. More specifically, the image generation unit 78 generates an image having a luminance channel Y and two color difference channels Cb and Cr related to color differences. At this time, as shown in FIG. 9, the image generation unit 78 uses either the B1 image signal or the B2 image signal selected by the image signal selection unit 72 using the setting of the depth of the blood vessel to be observed as the luminance channel Y. The calculated and reduced resolution image signal ΔB is assigned to the two color difference channels Cb and Cr. As a result, an image in which a running pattern of a blood vessel having a specific depth is emphasized with a color (hereinafter referred to as a specific depth blood vessel emphasized image) is generated as a display image.

  When the setting of the depth of the blood vessel to be observed is “polar surface blood vessel”, the image signal selection unit 72 selects the B1 image signal corresponding to the purple light V, so the image generation unit 78 uses the B1 image signal as the luminance channel Y. Assign to. This is because the depth of penetration to the observation target is lower for the purple light V than for the blue light B, and the contrast of the extreme surface blood vessels tends to be high, so that an image that makes it easy to observe the extreme surface blood vessels can be obtained. . For the same reason, when the depth setting of the blood vessel to be observed is “superficial blood vessel”, the contrast of the superficial blood vessel at a slightly deep position tends to be high, corresponding to the blue light B having a high depth of penetration to the observation target. Since the B2 image signal is selected by the image signal selection unit 72, the image generation unit 78 assigns the B2 image signal to the luminance channel Y.

  The image generator 78 multiplies the coefficient α and the coefficient β when assigning the calculation image signal ΔB to the color difference channels Cb and Cr. This is in order to align the color with the image displayed by the endoscope system that emphasizes and observes the surface blood vessels.

Specifically, in a conventional endoscope system having an enhanced observation mode for emphasizing observation of a superficial blood vessel, in the enhanced observation mode, an image of an observation object is captured by irradiating a narrow band of blue light to obtain a B image signal. The G image signal is acquired by capturing an observation target by irradiating a narrow-band green light. Then, the B image signal is assigned to the B channel (blue channel) and G channel (green channel) of the display image, and the G image signal is assigned to the R channel (red channel). The deep blood vessels are highlighted in green (cyan) color, and the superficial blood vessels in a shallow position under the mucous membrane are highlighted in red (magenta) color. ITU-R. In 601, the relationship between each RGB image signal, the luminance channel Y, and the color difference channels Cb, Cr is expressed by the following equations (1), (2), and (3).
Y = 0.299R + 0.587G + 0.114B (1)
Cb = −0.169−0.331G + 0.5G (2)
Cr = 0.5R−0.419G−0.081B (3)

In the equations (2) and (3) of the color difference channels Cb and Cr, when G is substituted for R and B is substituted for G, the color difference channels Cb, Cb, Cr can be represented by (GB).
Cb = −0.169G + 0.169B = 0.169 (GB) (4)
Cr = 0.5G-0.5B = 0.5 (GB) (5)
In the present embodiment, the polar surface blood vessels are extracted and displayed, so that the calculated image signal ΔB is used instead of the (GB) signal. That is, the coefficient α = 0.169 is multiplied to assign the calculated image signal ΔB to the color difference signal Cb, and the coefficient β = 0.5 is multiplied to assign the calculated image signal ΔB to the color difference signal Cr. Thereby, the endoscope system 10 displays an image having almost the same color as that of the conventional endoscope system. However, in order to emphasize the color difference between the superficial blood vessel and the superficial blood vessel located at a relatively deep position, the coefficient α and the coefficient β may be further multiplied by a coefficient depending on the setting or the like.

In order to generate a RGB specific depth blood vessel enhanced image from the luminance channel Y and the color difference channels Cb and Cr, ITU-R. According to the inverse transformation of 601
R = Y + 1.402Cr (7)
G = Y−0.344Cb−0.714Cr (8)
B = Y + 1.772 Cb (9)
Do by.

  The normal image generated by the normal image processing unit 66 and the specific depth blood vessel emphasized image generated by the special image processing unit 67 are input to the video signal generation unit 68. The video signal generation unit 68 converts a normal image or a specific depth blood vessel emphasized image into a video signal for display as an image that can be displayed on the monitor 18. Using this video signal, the monitor 18 displays a normal image and a specific depth blood vessel emphasized image.

  Next, a sequence of image processing in the special observation mode will be described with reference to FIG. First, when observing an observation target in the special observation mode, the depth of the blood vessel to be observed is set in the setting unit 71 using the console 19 (input unit) (S10). Specifically, a setting menu is displayed on the monitor 18 using the console 19, and the setting of the depth of the blood vessel to be observed is selected from “surface blood vessel” or “polar surface blood vessel”. In the following, it is assumed that the depth of the blood vessel to be observed is set to “polar surface blood vessel”.

  When the depth of the blood vessel to be observed is set in this way and switched to the special observation mode, the light source 20 generates purple light V and irradiates the observation target with the generated purple light V (S11). The imaging sensor 48 images the observation target irradiated with the purple light V (S12), and the image signal acquisition unit 53 acquires a B1 image signal corresponding to the purple light V (S13). As shown in FIG. 11, the B1 image signal 110 is an image signal obtained by imaging the observation target with the purple light V, so that the extreme surface blood vessels 124 can be observed in addition to the shape 112 such as the undulation of the observation target. Further, the superficial blood vessel 123 at a deeper position below the mucous membrane than the extreme superficial blood vessel 124 can also be observed by the B1 image signal 110.

  Next, the light source 20 generates the blue light B, irradiates the generated blue light B to the observation target (S14), and the imaging sensor 48 images the observation target irradiated with the blue light B (S15). Then, the image signal acquisition unit 53 acquires a B2 image signal corresponding to the blue light B (S16). As shown in FIG. 12, the B2 image signal 120 is an image signal obtained by imaging the observation target with the blue light B, and therefore the surface blood vessel 123 at a relatively deep position can be observed in addition to the shape 112 of the observation target. is there. Further, the polar surface blood vessel 124 can also be observed by the B2 image signal 120. When the B1 image signal 110 and the B2 image signal 120 are compared, the B1 image signal 110 has a higher contrast of the extreme surface blood vessel 124, and the B2 image signal 120 has a surface layer relatively deeper than the extreme surface blood vessel 124. The contrast of the blood vessel 123 is high.

  The B1 image signal and the B2 image signal obtained as described above are aligned by the alignment processing unit 62 (S17), and further subjected to brightness correction processing by the brightness correction processing unit 63 (S18). Then, it is input to the special image processing unit 67. In the special image processing unit 67, the calculation image signal ΔB is generated by the calculation image signal generation unit 76 (S19). When the setting of the depth of the blood vessel to be observed is “polar surface blood vessel”, the calculated image signal ΔB is relatively less than the original image signal (for example, the B1 image signal in FIG. 11 and the B2 image signal in FIG. 12). The pixel value of the superficial blood vessel 123 at a deep position is small, and the pixel value of the polar superficial blood vessel 124 is large. For this reason, as shown in FIG. 13, in the calculated image signal ΔB, the difference between the polar surface blood vessel 124 and the surface blood vessel 123 at a relatively deep position becomes more prominent than the original image signal. When the special image processing unit 67 generates the calculation image signal ΔB, the resolution reduction processing unit 77 further reduces the resolution of the calculation image signal ΔB (S20). As shown in FIG. 14, the surface blood vessel 123 and the extreme surface blood vessel 124 are blurred in the calculated image signal ΔB that has passed through the resolution reduction processing unit 77.

  In this way, the special image processing unit 67 generates the calculation image signal ΔB, and the special image processing unit 67 assigns the image signal selection unit 72 to the luminance channel Y of the specific depth blood vessel enhancement image generated by the image generation unit 78 for display. A signal is selected (S21). The image signal selection unit 72 selects the B2 image signal when the setting of the depth of the blood vessel to be observed is “surface blood vessel”, and selects B1 when the setting of the depth of the blood vessel to be observed is “polar surface blood vessel”. Since the image signal is selected, the B1 image signal is selected here.

  When the calculation image signal ΔB is generated by the calculation image signal generation unit 76 and the image signal is selected by the image signal selection unit 72, the special image processing unit 67 is selected by the image signal selection unit 72 by the image generation unit 78. By assigning the B1 image signal to the luminance channel Y and assigning the low-resolution computed image signal ΔB to the color difference channels Cr and Cb, a specific depth blood vessel emphasized image is generated. As shown in FIG. 15, in the specific depth blood vessel enhancement image 130 generated when the depth setting of the blood vessel to be observed is “polar surface blood vessel”, the surface blood vessel 123 is displayed in a cyan color. The extreme surface blood vessel 124 is displayed in a magenta color. For this reason, in the specific depth blood vessel enhancement image 130, the superficial blood vessel 123 and the polar superficial blood vessel 124 can be distinguished by color, and the polar superficial blood vessel 124 is displayed as an emphasized image that is substantially easy to observe.

  When the depth of the blood vessel to be observed is set to “surface blood vessel”, the pixel value of the superficial blood vessel 123 increases and the pixel value of the extreme surface blood vessel 124 decreases in the calculated image signal ΔB. Further, the B2 image signal is selected as the image signal assigned to the luminance channel Y of the specific depth blood vessel enhancement image. Therefore, contrary to the case where the depth setting of the blood vessel to be observed is “polar surface blood vessel”, the surface blood vessel 123 is displayed in magenta color, and the polar surface blood vessel 124 is colored in cyan color. Is displayed. For this reason, in the specific depth blood vessel enhancement image generated when the depth setting of the blood vessel to be observed is “surface blood vessel”, the surface blood vessel 123 and the polar surface blood vessel 124 can be distinguished by color, and substantially the surface layer. The blood vessel 123 can be easily observed.

  As described above, the endoscope system 10 sets the depth of the blood vessel to be observed, and generates an image signal to be assigned to the luminance channel Y when generating a specific depth blood vessel emphasized image that is a display image. Is changed according to the setting of the depth of the blood vessel to be observed. For this reason, in the specific depth blood vessel enhancement image, the contrast of the blood vessel at the set depth is high and easy to observe.

  Furthermore, the endoscope system 10 calculates the calculation image signal ΔB based on the difference (or ratio) between the B1 image signal corresponding to the violet light V and the B2 image signal corresponding to the blue light B, and the color difference channels Cb and Cr are calculated. The calculated image signal ΔB is assigned. Thus, by selecting an image signal to be assigned to the luminance channel Y, the contrast of the blood vessel of the set specific depth is high, and the comparison is made between the extreme surface blood vessel 124 and the extreme surface blood vessel 124 that have been difficult to identify conventionally. The superficial blood vessel 123 in a deep position can be visualized and highlighted with a difference in color.

  Further, due to the difference in the acquisition timing of the B1 image signal and the B2 image signal, a wrinkle occurs between the B1 image signal assigned to the luminance channel Y and the calculated image signal ΔB. As a result, the specific depth blood vessel emphasized image 130 has a color shift. May appear. For this reason, in the endoscope system 10, when assigning the calculation image signal ΔB to the color difference channels Cb and Cr, the calculation image signal ΔB is assigned to the color difference channels Cb and Cr after the resolution is reduced by the resolution reduction processing unit 77. Color shift is reduced.

  In the first embodiment, the image generation unit 78 assigns the B1 image signal to the luminance channel Y and assigns the calculation image signal ΔB to the color difference channels Cb and Cr, thereby specifying the specific depth blood vessel enhanced image in the YCbCr format. 130 is generated, but an RGB image having an R channel, a G channel, and a B channel may be generated. In this case, as shown in FIG. 16, the image generation unit 78 assigns the image signal selected by the image signal selection unit 72 to the G channel that contributes most to the luminance, and assigns the calculated image signal ΔB to the remaining B channel and R channel. assign.

[Second Embodiment]
In the first embodiment, the depth of the blood vessel to be observed is set to two types, “surface blood vessel” and “polar surface blood vessel”, and one of these is selected. It is preferable that the setting of can be set more finely and stepwise. For example, it is preferable that the depth from the mucous membrane can be set numerically. In this case, as illustrated in FIG. 17, the special image processing unit 67 includes an image signal selection unit 272 and a calculation image signal generation unit 276 instead of the image signal selection unit 72 and the calculation image signal generation unit 76 of the above embodiment. Is provided.

The image signal selection unit 272 includes a mixed image signal generation unit 273. The mixed image signal generation unit 273 generates a mixed image signal B _M obtained by mixing the B1 image signal and the B2 image signal. Further, the mixed image signal generation unit 273 generates a mixed image signal B _M by changing the mixing ratio of the B1 image signal and the B2 image signal according to the setting of the blood vessel depth. Specifically, when the depth of the blood vessel to be observed is set as a numerical value, the pixel values are averaged by weighting corresponding to the numerical value representing the depth of the blood vessel to be observed in the B1 image signal and the B2 image signal, A mixed image signal B _M is generated. For example, the range that can be set as the depth of the blood vessel to be observed is “0” to “100” (arbitrary unit), and the larger the value, the deeper the position. In this case, when the depth of the blood vessel to be observed is set to “30”, the mixed image signal generation unit 273 converts the B1 image signal and the B2 image signal to 7: 3 (= 1-30 / 100: 30/100). The mixed image signal B _M is generated by performing a weighted average with the mixing ratio of Similarly, when the depth of the blood vessel to be observed is set to “60”, the mixed image signal unit 273 converts the B1 image signal and the B2 image signal to 4: 6 (= 1-60 / 100: 60/100). The mixed image signal B _M is generated by performing weighted averaging with the mixing ratio. Of course, when the setting of the depth of the blood vessel to be observed is “0”, the mixing ratio of the B1 image signal and the B2 image signal is 1: 0, and the mixed image signal B _M is equal to the B1 image signal, When the depth setting is “100”, the mixing ratio of the B1 image signal and the B2 image signal is 0: 1, and the mixed image signal B _M is equal to the B2 image signal.

  The arithmetic image signal generation unit 276 weights the B1 image signal and the B2 image signal according to the setting of the depth of the blood vessel to be observed in the same manner as the mixed image signal generation unit 273, and calculates the difference or ratio between them. Thus, the calculation image signal ΔB is generated. As a result, the purple light V graph or the blue light B graph in FIG. 8 is relatively shifted up and down, so that the intersection of the purple light V graph and the blue light B graph is shifted left and right. For this reason, the boundary between the blood vessel having a small pixel value (black) and the blood vessel having a large pixel value (white) in the calculated image signal ΔB is changed. The depth of the highlighted blood vessel changes.

Then, in the image generation unit 78, the mixed image signal B _M is assigned to the luminance channel Y, the calculation image signal ΔB generated by the calculation image signal generation unit 276 is assigned to the color difference channels Cb and Cr, and the specific depth blood vessel emphasized image is assigned. Generate.

In the endoscope system 10 of the first embodiment, either the B1 image signal or the B2 image signal is selected and assigned to the luminance channel Y of the specific depth blood vessel emphasized image, but the B1 image signal, B2 An image signal or any one of the mixed image signals B _M of the second embodiment may be selected, and the selected image signal may be assigned to a luminance channel to generate a specific depth blood vessel enhanced image. . In this case, “Specify the depth of the blood vessel” can be selected in addition to “Surface blood vessel” and “Polar surface blood vessel” as the setting of the depth of the blood vessel to be observed. In the case of “superficial blood vessel”, the B2 image signal is assigned to the luminance channel Y, and when the depth setting of the blood vessel to be observed is “polar surface blood vessel”, the B1 image signal is assigned to the luminance channel Y, When the depth setting is “specify the depth of the blood vessel”, the mixed image signal B _M generated according to the specified depth may be assigned to the luminance channel Y.

  When the mixing ratio of the B1 image signal and the B2 image signal is set to 7: 3, a blood vessel emphasized image having a specific depth close to an image displayed by a conventional endoscope system having an enhanced observation mode for emphasizing observation of a surface blood vessel is obtained. It is done.

[Third Embodiment]
In the first and second embodiments, the violet light V and the blue light B are used to highlight the extreme surface blood vessels or the superficial blood vessels. However, the same principle is referred to as a middle layer, a middle depth layer, or a deep layer. It is also possible to highlight blood vessels that are deeper in the submucosa. For example, as shown in FIG. 18, the endoscope system 300 according to the third embodiment uses a “medium deep blood vessel” as a setting of the depth of a blood vessel to be observed, in addition to “polar surface blood vessel” and “surface blood vessel”. The setting of the depth of the blood vessel to be observed is provided with the light source control unit 322 input from the setting unit 71.

  The light source control unit 322 controls the lighting and extinction of each LED 23a to 23d of the light source 20 and the amount of emitted light as in the first and second embodiments, but in particular, by setting the depth of the blood vessel to be observed. Each wavelength band of the first illumination light and the second illumination light used in the observation mode is controlled. Specifically, when the depth setting of the blood vessel to be observed is “polar superficial blood vessel” or “superficial blood vessel”, the violet light V is used as the first illumination light and the blue light as in the first embodiment. Let B be the second illumination light. On the other hand, when the setting of the depth of the blood vessel to be observed is “medium deep blood vessel”, the blue light B is the first illumination light and the green light G is the second illumination light.

  When the blue light B is used as the first illumination light and the green light G is used as the second illumination light, an image signal obtained by imaging the observation target irradiated with the blue light B with the B pixel is used as the first image signal, and the green light is used. An image signal obtained by imaging the observation target irradiated with the light G with the B pixel is defined as a second image signal. In this way, when the specific depth blood vessel enhanced image is generated, the second image signal is selected and assigned to the luminance channel Y, and the calculated image signal ΔB generated by subtracting the B2 image signal from the logarithmically converted B1 image signal. Can be assigned to the color difference channels Cb and Cr, the middle and deep blood vessels can be highlighted with respect to the surface blood vessels. On the contrary, if the first image signal is selected and assigned to the luminance channel Y, and the calculated image signal ΔB generated by subtracting the B1 image signal from the B2 image signal after logarithmic conversion is assigned to the color difference channels Cb and Cr, the surface layer A blood vessel and a middle-deep blood vessel can be represented by different colors, and a surface blood vessel can be highlighted with respect to the middle-deep blood vessel.

  As in the endoscope system 300 of the third embodiment, the setting of the depth of the blood vessel to be observed is input from the setting unit 71 to the light source control unit 322, and the light source control unit 322 If each wavelength band of the first illumination light and the second illumination light used in the special observation mode is controlled by setting the depth (including the case where the spectral spectrum is changed), the middle layer, or further divided into the middle layers Blood vessels and deep blood vessels can be highlighted.

  In the third embodiment, the light source control unit 322 performs control to switch the wavelength bands of the first illumination light and the second illumination light used in the special observation mode by setting the depth of the blood vessel to be observed. The light source control unit 322 may switch the balance of light emission amounts of the first illumination light and the second illumination light (hereinafter referred to as a light amount ratio) by setting the depth of the blood vessel to be observed. For example, when the purple light V is the first illumination light and the blue light B is the second illumination light as in the first and second embodiments, the purple light V and the blue light are set according to the depth setting of the blood vessel to be observed. If the light quantity ratio of B is controlled, the weighting performed on the B1 image signal and the B2 image signal in the second embodiment can be performed at the stage of obtaining the B1 image signal and the B2 image signal.

  In the third embodiment, the light source control unit 322 performs control to switch the wavelength bands of the first illumination light and the second illumination light used in the special observation mode by setting the depth of the blood vessel to be observed. In addition to the combination of the wavelength bands of the first illumination light and the second illumination light, the color of the pixel that acquires the image signal assigned to the luminance channel Y of the specific depth blood vessel emphasized image, the first illumination light, and the second illumination light The light amount ratio or the like may be changed. For example, purple light V and blue light B are simultaneously emitted at a light quantity ratio of 7: 3, and an observation object irradiated with this illumination light is imaged with the B pixel and imaged with the G pixel. A specific depth blood vessel enhanced image may be generated using the obtained image signal. Also, illumination light in which purple light V and blue light B are simultaneously emitted at a light quantity ratio of 7: 3 and illumination light in which blue light B and green light G are simultaneously emitted at a light quantity ratio of 1: 1 are captured. Switching may be performed for each frame, and image signals obtained in each frame may be used in combination. In this way, by combining the control of the wavelength bands of the first illumination light and the second illumination light, the pixel for obtaining the image signal used for the generation of the specific depth blood vessel emphasized image, the control of the light amount ratio of the illumination light, etc. It is possible to flexibly cope with a finer setting of the depth of the blood vessel to be observed.

[Fourth Embodiment]
In the first to third embodiments, the depth of the blood vessel to be observed is set by using the console 19 functioning as the input unit. However, the depth of the blood vessel to be automatically observed by the endoscope system is set. You may set it. In this case, as in the endoscope system 400 illustrated in FIG. 19, for example, the observation distance acquisition unit 419 is provided in the processor device 16. The imaging magnification of the imaging optical system 30b has a correlation with the observation distance. When the imaging magnification is small, the far-field observation is performed. When the observation distance is long and the imaging magnification is large, the near-field observation is performed. It can be said that the observation distance is short. For this reason, the observation distance acquisition unit 419 acquires the imaging magnification of the imaging optical system 30b from the zoom operation unit 13b. The observation distance acquisition unit 419 inputs the acquired imaging magnification as an observation distance, or converts the acquired imaging magnification into an observation distance and inputs it to the setting unit 471. The setting unit 471 uses the observation distance input from the observation distance acquisition unit 419 to set the depth of the blood vessel to be observed. For example, when the observation distance is shorter than a predetermined threshold, the depth setting of the blood vessel to be observed is automatically set to “polar surface blood vessel”, and when the observation distance is equal to or larger than the threshold, the depth of the blood vessel to be observed is set. This setting is automatically set to “Superficial blood vessel”.

  In this way, if the setting of the depth of the blood vessel to be observed is automated, for example, an image in which an appropriate blood vessel is emphasized according to the situation can be displayed on the monitor 18 simply by operating the zoom operation unit 13b naturally. it can.

  In the fourth embodiment, the observation distance acquisition unit 419 acquires the imaging magnification of the imaging optical system 30b, but the observation distance acquisition unit 419 receives the image signal from the image signal acquisition unit 53, the image processing switching unit 61, and the like. And the observation distance may be calculated using the acquired image signal.

  In the first to third embodiments, the depth of the blood vessel to be observed is set using the console 19, and in the fourth embodiment, the depth of the blood vessel to be observed is automatically set. Instead of this, the depth of the blood vessel to be observed may be set by operating a button or the like provided on the endoscope 12. For example, the special observation mode is subdivided according to the type of blood vessel depth to be observed, such as the polar surface blood vessel emphasizing mode or the surface blood vessel emphasizing mode, and the operation signal of the mode changeover switch 13a is changed as shown in FIG. It is input to the image signal selection unit 72 and the calculation image signal generation unit 76. The image signal selection unit 72 and the calculation image signal generation unit 76 observe the normal observation mode, the polar surface blood vessel enhancement mode, the superficial blood vessel enhancement mode, and the like each time an operation signal is input from the mode switch 13a. Each special observation mode subdivided according to the type of blood vessel depth may be toggle-switched. In this way, since the setting of the depth of the blood vessel to be observed using the endoscope 12 can be switched, convenience is improved.

  In the above modification, the setting of the depth of the blood vessel to be observed is switched by operating the mode switch 13a, but other buttons, levers, switches (foot pedals, etc.) may be used.

  In the first to fourth embodiments, the cutoff frequency of the LPF used in the resolution reduction processing unit 77 is set in advance, but the cutoff frequency of the LPF is made variable and the cutoff frequency of the LPF is dynamically set. It is preferable to do. For example, as shown in FIG. 21, the alignment accuracy of the B1 image signal and the B2 image signal is input from the alignment processing unit 62 to the resolution reduction processing unit 77. Then, the resolution reduction processing unit 77 changes the LPF cutoff frequency (the intensity of the resolution reduction processing) according to the alignment accuracy of the B1 image signal and the B2 image signal. Specifically, as the alignment accuracy between the B1 image signal and the B2 image signal is higher, the LPF cutoff frequency is set to a higher frequency to reduce the intensity of the resolution reduction processing, and the alignment between the B1 image signal and B2 is performed. The lower the accuracy, the greater the strength of the resolution reduction processing by setting the LPF cutoff frequency to a lower frequency. In this way, the degree of resolution reduction of the calculation image signal ΔB by the resolution reduction processing unit 77 is optimized, and a blood vessel (for example, the polar surface blood vessel 124) having a specific depth can be appropriately highlighted.

  When displaying or saving a specific depth blood vessel emphasized image as a still image, the cutoff frequency of the LFP is at least 1/8 or less of the Nyquist frequency on the basis of the resolution of the specific depth blood vessel emphasized image to be generated. It is preferable to set within the range to be left.

  In the above modification, the resolution reduction processing unit 77 adjusts the intensity of the resolution reduction processing according to the accuracy of the registration processing of the registration processing unit 62, but on the contrary, the resolution reduction processing The alignment processing unit 62 may adjust the accuracy of the alignment processing according to the strength of the resolution reduction processing performed by the unit 77. In this case, the alignment processing unit 62 sets the alignment accuracy of the B1 image signal and the B2 image signal higher as the cutoff frequency of the LPF is larger and the strength of the resolution reduction processing is smaller.

  The accuracy of the alignment processing between the B1 image signal and the B2 image signal performed by the alignment processing unit 62 is variable, and a still image of the specific depth blood vessel emphasized image is displayed or stored, and a moving image of the specific depth blood vessel emphasized image It is preferable to change the accuracy of the alignment process depending on whether or not is displayed. For example, when displaying a moving image composed of a blood vessel image having a specific depth on the monitor 18, the alignment processing unit 62 displays (or stores) a still image of the blood vessel image having a specific depth on the monitor 18. The B1 image signal and the B2 image signal are aligned with low first accuracy. On the other hand, when displaying a still image of a specific depth blood vessel image on the monitor 18, the alignment processing unit 62 has higher second accuracy than when displaying a moving image of a specific depth blood vessel image on the monitor 18. , B1 image signal and B2 image signal are aligned. In this way, when displaying a moving image, a specific depth blood vessel emphasis image can be generated at high speed within a range where color misregistration is not noticeable, and when acquiring a still image in which color misregistration is conspicuous, a specific depth without color misregistration can be obtained. A blood vessel enhanced image can be generated.

  The alignment processing unit 62 may change the alignment accuracy between the B1 image signal and the B2 image signal according to the size of the specific depth blood vessel image to be generated. For example, when the specific depth blood vessel image to be generated is large, a slight misalignment is also conspicuous, so the alignment processing unit 62 aligns the B1 image signal and the B2 image signal with high accuracy and generates the specific depth. When the blood vessel image is small, misalignment is not noticeable. Therefore, the B1 image signal and the B2 image signal are aligned with low accuracy. When the specific depth blood vessel image to be generated is large so that the processing load of the processor device 16 is constant regardless of the size of the specific depth blood vessel image to be generated, the alignment accuracy so that the processing load is acceptable. May be dropped.

  As described above, when the alignment processing unit 62 changes the accuracy of the alignment processing between when displaying a moving image and when acquiring a still image, or when changing the alignment accuracy according to the size of the specific depth blood vessel image The resolution reduction processing unit 77 preferably changes the cutoff frequency of the LPF according to the alignment accuracy. For example, when displaying a moving image, the alignment processing unit 62 reduces the alignment accuracy of the B1 image signal and the B2 image signal, and instead, the resolution reduction processing unit 77 shifts the cutoff frequency of the LPF to the lower frequency side. And good. Further, when acquiring a still image, the alignment processing unit 62 increases the alignment accuracy of the B1 image signal and the B2 image signal, and instead, the low resolution processing unit 77 shifts the cutoff frequency of the LFP to the high frequency side. And good. That is, it is preferable to give priority to the LPF of the resolution reduction processing unit 77 that places a small processing burden on the processor device 16 when displaying a moving image, and to give priority to accurate alignment by the alignment processing unit 62 when acquiring a still image.

  Note that the alignment processing unit 62 may perform alignment between the B1 image signal and the B2 image signal only when acquiring a still image without performing alignment between the B1 image signal and the B2 image signal when displaying a moving image.

  In the above-described embodiment, the resolution reduction processing unit 77 reduces the resolution of the calculated image signal ΔB by the LPF. However, instead of the LPF, the resolution reduction processing unit 77 reduces the calculated image signal ΔB and then expands it to the original size. However, the resolution can be reduced. As described above, when the calculation image signal ΔB is reduced and enlarged to impose a low resolution, it is preferable to employ a reduction method with less aliasing when the calculation image signal ΔB is reduced. For example, after the reduction by the area average method, the calculation image signal ΔB can be reduced in resolution by cubic spline interpolation.

  When the polar surface blood vessel 124 is distinguished from the surface blood vessel 123 and highlighted as in the first to fourth embodiments, both the wavelength bands of the first illumination light and the second illumination light have a wavelength of 500 nm or less. It is preferable to be within the range. Specifically, as in the above embodiment, the violet light V having a central wavelength at 405 ± 10 nm and the blue light B having a central wavelength at 460 ± 10 nm are used as the first illumination light and the second illumination light. Is preferred. More preferably, violet light having a central wavelength of 405 ± 10 nm and blue light having a central wavelength of 445 ± 10 nm are used as the first illumination light and the second illumination light. Blue light having a central wavelength of 445 ± 10 nm can be generated from the blue light B by using, for example, an optical filter that cuts the long wavelength side of the B-LED 23b in the optical path of the B-LED 23b. The B-LED 23b may be replaced with another LED that emits blue light having a central wavelength of 445 ± 10 nm.

  In the case where highlighting is performed by dividing the middle-deep blood vessel into a middle-deep blood vessel at a relatively shallow position and a middle-deep layer blood vessel at a relatively deep position, the wavelength bands of the first illumination light and the second illumination light are: Both are preferably 500 nm or more. Specifically, it is preferable to use light having a wavelength of about 500 nm and light having a wavelength of about 600 nm as the first illumination light and the second illumination light.

  In the first to fourth embodiments, the calculation image signal generation unit 76 generates the calculation image signal ΔB representing the traveling pattern of the extreme surface blood vessel 124 at a specific depth below the mucous membrane. The calculation image signal D representing the blood vessel density and the calculation image signal S representing the oxygen saturation of hemoglobin contained in the blood vessel or the like (hereinafter referred to as blood vessel oxygen saturation) may be generated.

  The calculated image signal D representing the blood vessel density can be calculated using the calculated image signal ΔB of the above embodiment. For example, since the calculated image signal ΔB of the above embodiment is an image signal obtained by extracting the polar surface blood vessel 124 (see FIG. 13), the area of the polar surface blood vessel 124 in the unit area is calculated using the calculated image signal ΔB. By calculating the ratio for each pixel, a calculation image signal D representing the blood vessel density of the polar surface blood vessel 124 can be generated. When generating the calculation image signal D in this way, the image generation unit 78 assigns the B1 image signal to the luminance channel Y and assigns the calculation image signal D to the color difference channels Cb and Cr, so that the polar surface blood vessel 124 can be generated. A blood vessel density image representing the blood vessel density is generated. The blood vessel density image can give a direct suggestion to diagnosis such as stage discrimination of Barrett's adenocarcinoma.

  When generating the calculation image signal S representing the oxygen saturation of the blood vessel, for example, the first blue light having the center wavelength of 445 ± 10 nm, the green light G, and the red light R are irradiated to image the observation target, and The second blue light, the green light G, and the red light R having a center wavelength of 473 ± 10 nm are irradiated to image the observation target. The first blue light is a first optical filter that limits the wavelength band of the blue light B emitted from the B-LED 23b so that the center wavelength is 445 ± 10 nm (for example, an optical filter that cuts the long wavelength side of the blue light B). Can be generated from the blue light B. Similarly, the second blue light is a second optical filter that limits the wavelength band of the blue light B emitted from the B-LED 23b so that the center wavelength is 473 ± 10 nm (for example, cuts the short wavelength side of the blue light B). It can be generated from the blue light B by using an optical filter.

  The first blue light has a wavelength band in which there is almost no difference in the extinction coefficient between oxyhemoglobin and reduced hemoglobin. On the other hand, the second blue light has a wavelength band in which there is a difference in the extinction coefficient between oxyhemoglobin and reduced hemoglobin. For this reason, the ratio or difference between the image signals obtained by imaging the observation object irradiated with the first blue light and the second blue light has a correlation with the oxygen saturation. Therefore, a correlation that associates the ratio or difference between the image signals corresponding to the first blue light and the second blue light with the oxygen saturation is obtained in advance by experiments or the like, and the arithmetic image signal generation unit 76 holds this correlation in advance. Keep it. Then, the calculation image signal generation unit 76 calculates the ratio or difference between the image signals corresponding to the first blue light and the second blue light, and compares them with the correlation so that each pixel has oxygen saturation of the observation target. An arithmetic image signal S representing the degree value is generated. In the same manner as the normal image processing unit 66, the image generation unit 78 irradiates the first blue light, the green light G, and the red light and images the observation target to obtain the normal image signal. Generate. Then, by assigning the normal image signal to the luminance channel Y and assigning the calculation image signal S representing the oxygen saturation to the color difference channels Cb and Cr, an oxygen saturation image representing the oxygen saturation of the observation target is generated. The oxygen saturation image generated in this way can display information useful for diagnosis of oxygen saturation.

  In the above embodiment, the present invention is implemented by the endoscope system 10 that performs observation by inserting the endoscope 12 provided with the imaging sensor 48 into the subject. The present invention is also suitable. For example, as shown in FIG. 22, the capsule endoscope system includes at least a capsule endoscope 500 and a processor device (not shown).

  The capsule endoscope 500 includes a light source 502, a light source control unit 503, an image sensor 504, a signal processing unit 506, and a transmission / reception antenna 508. The light source 502 is configured in the same manner as the light source 20 of each of the above embodiments. The light source control unit 503 controls the driving of the light source 502 in the same manner as the light source control unit 22 of each of the above embodiments. Further, the light source control unit 503 can communicate with the processor device of the capsule endoscope system wirelessly by the transmission / reception antenna 508. The processor device of the capsule endoscope system is substantially the same as the processor device 16 of each of the above embodiments, but the signal processing unit 506 has functions of a normal image processing unit 66 and a special image processing unit 67. The blood vessel emphasized image signal generated by the signal processing unit 506 is transmitted to the processor device via the transmission / reception antenna 508. The image sensor 504 is configured in the same manner as the image sensor 48 of each of the above embodiments.

DESCRIPTION OF SYMBOLS 10,300,400 Endoscope system 12 Endoscope 14 Light source apparatus 16 Processor apparatus 20,502 Light source 22,322,503 Light source control part 53 Image signal acquisition part 67 Special image processing part 71,471 Setting part 72 Image signal selection Unit 76, 276 Computation image signal generation unit 77 Resolution reduction processing unit 78 Image generation unit 419 Observation distance acquisition unit

Claims (15)

A light source that generates illumination light;
An imaging sensor for imaging an observation target irradiated with the illumination light;
A first image signal corresponding to the first illumination light among the illumination light is obtained, and a second image signal corresponding to the second illumination light having a wavelength band different from the first illumination light among the illumination light is obtained. An image signal acquisition unit to acquire;
A setting unit for setting the depth of the blood vessel to be observed;
The image signal of the first image signal, the second image signal, or a mixed image signal obtained by mixing the first image signal and the second image signal using the blood vessel depth setting An image signal selector for selecting
An image generation unit that generates an image in which the image signal selected by the image signal selection unit is assigned to a luminance channel;
An endoscope system comprising: A calculation image signal generation unit that generates a calculation image signal using the first image signal and the second image signal;
The endoscope system according to claim 1, wherein the image generation unit generates an image in which the image signal selected by the image signal selection unit is allocated to a luminance channel and the calculation image signal is allocated to two color difference channels. .   The endoscope system according to claim 2, wherein the calculation image signal generation unit changes a generation method of the calculation image signal according to a setting of the depth of the blood vessel. The image signal selection unit includes a mixed image signal generation unit that generates the mixed image signal when the mixed image signal is selected.
The mixed image signal generation unit generates the mixed image signal by changing a mixing ratio of the first image signal and the second image signal according to the setting of the depth of the blood vessel. The endoscope system described in 1.   The wavelength ranges of the first illumination light and the second illumination light are controlled by setting the depth of the blood vessel, or the light amounts of the first illumination light and the second illumination light are set by setting the depth of the blood vessel. The endoscope system of any one of Claims 1-3 provided with the light source control part which controls the balance of. An observation distance acquisition unit for acquiring an observation distance of the observation target;
The endoscope system according to any one of claims 1 to 5, wherein the setting unit sets the depth of the blood vessel using the observation distance. An imaging optical system that forms an image of the observation target on the imaging sensor and has a variable imaging magnification,
The endoscope system according to claim 6, wherein the observation distance acquisition unit acquires the imaging magnification of the imaging optical system as the observation distance.   The endoscope system according to any one of claims 1 to 7, further comprising an input unit for inputting the setting of the depth of the blood vessel to the setting unit. A light source device having the light source, an endoscope having the imaging sensor, and a processor device having the image generation unit,
The endoscope system according to claim 8, wherein the input unit is provided in the endoscope. A light source device having the light source, an endoscope having the imaging sensor, and a processor device having the image generation unit,
The endoscope system according to claim 8, wherein the input unit is provided in the processor device.   An alignment processing unit that corrects at least one of the first image signal or the second image signal and aligns the observation target represented by the first image signal with the observation target represented by the second image signal. The endoscope system according to claim 2 or 3.   A brightness correction processing unit that corrects at least one of the first image signal or the second image signal and sets a ratio between the brightness of the first image signal and the brightness of the second image signal to a specific ratio. The endoscope system according to 2 or 3. In a processor device of an endoscope system having a light source that generates illumination light and an imaging sensor that images an observation target irradiated with the illumination light,
A first image signal corresponding to the first illumination light among the illumination light is obtained, and a second image signal corresponding to the second illumination light having a wavelength band different from the first illumination light among the illumination light is obtained. An image signal acquisition unit to acquire;
A setting unit for setting the depth of the blood vessel to be observed;
The image signal of the first image signal, the second image signal, or a mixed image signal obtained by mixing the first image signal and the second image signal using the blood vessel depth setting An image signal selector for selecting
An image generation unit that generates an image in which the image signal selected by the image signal selection unit is assigned to a luminance channel;
A processor device comprising: A light source generating illumination light;
An imaging sensor imaging the observation object irradiated with the illumination light;
The image signal acquisition unit acquires a first image signal corresponding to the first illumination light in the illumination light, and corresponds to a second illumination light having a wavelength band different from the first illumination light in the illumination light. Obtaining a second image signal to:
A step of setting a depth of a blood vessel to be observed by the setting unit;
The image signal selection unit uses the setting of the depth of the blood vessel to select the first image signal, the second image signal, or a mixed image signal obtained by mixing the first image signal and the second image signal. Selecting any one of the image signals;
An image generation unit generating an image in which the image signal selected by the image signal selection unit is assigned to a luminance channel;
A method of operating an endoscope system comprising: In an operation method of a processor device of an endoscope system, comprising: a light source that generates illumination light; and an imaging sensor that images an observation target irradiated with the illumination light.
The image signal acquisition unit acquires a first image signal corresponding to the first illumination light in the illumination light, and corresponds to a second illumination light having a wavelength band different from the first illumination light in the illumination light. Obtaining a second image signal to:
A step of setting a depth of a blood vessel to be observed by the setting unit;
The image signal selection unit uses the setting of the depth of the blood vessel to select the first image signal, the second image signal, or a mixed image signal obtained by mixing the first image signal and the second image signal. Selecting any one of the image signals;
An image generation unit generating an image in which the image signal selected by the image signal selection unit is assigned to a luminance channel;
A method of operating a processor device comprising:

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