JP2012170639A - Endoscope system, and method for displaying emphasized image of capillary of mucous membrane surface layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-resolution image of a capillary of a mucous membrane surface layer for a diagnosis.SOLUTION: A color filter 37 of a CCD 33 has a sub-sensitivity region sensing the reflected light of narrow band light of central wavelength of 405 nm, in a sensitivity region of a G pixel. When non-enlargement is selected by a zoom operating switch 18, an image processing circuit 49 extracts a sub-sensitivity region component (a capillary component of the mucous membrane surface layer) b' from a G pixel value g by correlative operation to an R pixel value r. A display control circuit 50 allocates a B pixel value b and the sub-sensitivity region component b' to B, G channels of a monitor 19 and a medium-deep blood vessel component g' to an R channel respectively. An emphasized image of the capillary colored in green from blue is displayed on the monitor 19.

Description

  The present invention relates to an endoscope system that displays an enhanced image of capillaries on the mucosal surface layer, and an enhanced image display method for capillaries on the mucosal surface layer.

  Examination using an endoscope is widely used in the medical field. As is well known, the endoscope irradiates the observation site of the subject with illumination light from the tip of the insertion portion to be inserted into the subject, and captures an image of the observation site.

  Conventionally, a white light source such as a xenon lamp or a metal halide lamp has been used as the light source of the illumination light. However, in order to easily find a lesion, light of a narrow wavelength band (narrow band light) is irradiated to the observation site. The technique of imaging and observing the reflected light is in the spotlight (see Patent Documents 1 and 2). According to this method, it is possible to easily obtain an image in which blood vessels in the submucosal layer are emphasized and an image in which organ structures such as the stomach wall and intestinal surface tissue are emphasized.

  Patent Document 1 discloses a mode in which a band-limiting filter is arranged in an optical path of illumination light to produce narrow-band light, and reflected light of the narrow-band light is imaged by a CCD having a color filter disposed on the front surface (second embodiment). Is described. In Patent Document 2, an imaging optical system (lens, imaging element, etc.) for narrow-band light observation is mounted on an endoscope separately from normal observation for irradiating white light and imaging the reflected light. Both Patent Documents 1 and 2 exemplify capillaries on the surface of the mucous membrane as observation targets.

JP 2002-095635 A JP 2007-111357 A

  When capillaries on the mucosal surface layer are to be observed, the capillaries are very thin, about 10 μm. Therefore, select the performance of the image sensor such as a CCD and the non-enlargement of the zoom function, or cover the tip of the insertion part of the endoscope. There is a problem that sufficient resolution cannot be obtained depending on the observation state where observation is performed away from the observation site. When an image with insufficient resolution is used for diagnosis, there is a risk that the lesion may be overlooked or a normal part may be determined as a lesion.

  When observing capillaries, the image of the reflected light is emitted by irradiating the observed portion with blue narrow-band light. When a primary color filter is used, an image of the capillaries is formed on the B pixels. However, in a general Bayer arrangement as a primary color filter, the number of B pixels relative to the total number of pixels is relatively small (when the total number of pixels is N, the number of B pixels is N / 4), and an observation image of capillary blood vessels Cause the lack of resolution. As a solution, it is conceivable to increase the definition of the pixel. However, the aperture of the pixel on which the reflected light is incident becomes small and the amount of light is insufficient. As a result, the S / N ratio is lowered, so that it cannot be adopted.

  In Patent Documents 1 and 2, there is no mention of the problem of a decrease in resolution when a capillary vessel is an observation object, and no countermeasures are taken.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a high-resolution image of capillary blood vessels on the surface of the mucosa.

  In order to achieve the above object, an endoscope system according to the present invention includes a first irradiating means for irradiating an observation site of a subject with white light having a broad wavelength band, and a blue light whose wavelength band is limited together with white light. A second irradiating means for irradiating the observation site with a narrow band of light and an imaging means for imaging the reflected light from the observation site, provided with RGB primary color filters and the number of G pixels> the number of B pixels. In addition to the green main sensitivity region, the G pixel has a sub-sensitivity region sensitive to the reflected light of the narrow band light, and performs a correlation operation between the pixel values of the G pixel and the R pixel, thereby obtaining a pixel of the G pixel. Extraction means for extracting the sub-sensitivity region components from the values, and display for displaying on the monitor an enhanced image of the capillaries on the mucosal surface layer based on the pixel values of the B pixels and the sub-sensitivity region components extracted by the extraction means And a control means.

  When the zoom function is provided, the extraction unit extracts a component of the sub-sensitivity region when non-enlargement is selected by the zoom operation, and the display control unit is configured when non-enlargement is selected by the zoom operation. The highlighted image is displayed on the monitor based on the pixel value of the B pixel and the component of the sub sensitivity area. Note that zooming in / out may be performed in two stages or more. In the case of multi-stage zoom, when the widest end is selected, or when several stages on the wide end are selected, the sub-sensitivity region components are extracted, the pixel values of the B pixels, and the sub-sensitivity region components are The original emphasized image is displayed.

  The first irradiation unit and the second irradiation unit can independently control the intensity of white light and narrowband light. When the zoom function is provided, when the non-enlargement is selected in the zoom operation, the first irradiation unit and the first irradiation unit are configured so that the intensity of the narrow band light is stronger than the white light than when the enlargement is selected. Control two irradiation means. In the case of multi-stage zoom, as described above, the intensity ratio of white light and narrow-band light is increased so that the intensity of narrow-band light is increased when the widest end side is selected or when several steps on the wide-end side are selected. To change.

  The extraction unit extracts a component of the main sensitivity region from the pixel value of the G pixel. You may provide the binning process means which performs a binning process with respect to the component of the main sensitivity area | region extracted by the said extraction means. The binning processing means may perform a binning process on the pixel value of the R pixel.

  The display control means assigns the pixel value of the B pixel and the component of the sub sensitivity region to the B and G channels of the monitor, and assigns the component of the main sensitivity region to the R channel of the monitor.

  The extraction means performs extraction from the pixel value of the G pixel after pixel interpolation.

  The sub-sensitivity region has a center wavelength at a wavelength of 380 nm to 450 nm, and the sensitivity at the center wavelength is preferably 1/5 or more of the sensitivity of the B pixel at the center wavelength.

  The first irradiation means has a laser light source that emits blue light and a wavelength conversion member that excites and emits light from green to yellow by blue light, and mixes blue light and excitation light to obtain white light. The second irradiating means has a laser light source that emits blue narrow-band light having a center wavelength of 405 nm.

  The primary color filter is a Bayer array.

  The emphasis image display method for capillary blood vessels of the mucosal surface layer of the present invention irradiates the observation site of the subject with white light with a broad wavelength band and blue narrow band light with a limited wavelength band, and the reflected light is RGB primary color filters are arranged, the number of G pixels> the number of B pixels, and the G pixels are imaged by an imaging means having a sub-sensitivity area sensitive to the reflected light of the narrow band light in addition to the green main sensitivity area, By performing the correlation calculation of the pixel values of the G pixel and the R pixel, the sub-sensitivity region components are extracted from the pixel values of the G pixel, and the mucosa based on the pixel values of the B pixel and the extracted sub-sensitivity region components An enhanced image of the surface capillary is displayed on a monitor.

  According to the present invention, the G pixel is provided with a sub-sensitivity region that is sensitive to the reflected light of the narrow band light, and the component of the sub-sensitivity region is extracted from the pixel value of the G pixel, and based on this, the capillaries on the mucous membrane surface layer are enhanced. Since the image is displayed, a high-resolution capillary blood vessel image on the mucosal surface layer can be used for diagnosis.

It is an external view which shows the structure of an electronic endoscope system. It is a block diagram which shows the structure of an electronic endoscope system. It is a figure which shows the color filter of a Bayer arrangement. It is a graph which shows the spectral sensitivity characteristic of each RGB pixel of CCD. It is a figure which shows the high resolution process.

  In FIG. 1, the electronic endoscope system 2 includes an electronic endoscope 10, a processor device 11, and a light source device 12. As is well known, the electronic endoscope 10 includes a flexible insertion portion 13 to be inserted into a subject (patient), an operation portion 14 connected to a proximal end portion of the insertion portion 13, and a processor device 11. And a connector 15 connected to the light source device 12, an operation unit 14, and a universal cord 16 that connects the connectors 15.

  The operation unit 14 includes an angle knob for bending the distal end 17 of the insertion unit 13 in the vertical and horizontal directions, an air supply / water supply button for ejecting air and water from the air supply / water supply nozzle, and an observation image. An operation member such as a release button for recording a still image or a zoom operation switch 18 for instructing an enlargement / non-expansion (telephoto / wide-angle) imaging of an observation site is provided.

  Further, a forceps port through which a treatment tool such as an electric knife is inserted is provided on the distal end side of the operation unit 14. The forceps port communicates with a forceps outlet provided at the distal end 17 through a forceps channel in the insertion portion 13.

  The processor device 11 is electrically connected to the light source device 12 and comprehensively controls the operation of the electronic endoscope system 2. The processor device 11 supplies power to the electronic endoscope 10 via the universal cord 16 and a transmission cable inserted into the insertion portion 13, and controls the drive of the CCD 33 (see FIG. 2) mounted on the distal end 17. In addition, the processor device 11 receives the imaging signal output from the CCD 33 via the transmission cable, and performs various processes on the received imaging signal to generate image data. The image data generated by the processor device 11 is displayed as an observation image on a monitor 19 connected to the processor device 11 by a cable.

  The electronic endoscope system 2 includes a normal observation mode in which white light is irradiated on a region to be observed of a subject for observation, and white light and blue light (narrow band light having a central wavelength of 405 nm) on the region to be observed. ) And a special observation mode in which observation is performed while paying attention to a surface blood vessel (capillary blood vessel) among blood vessels in the observation site. Switching between the modes is performed by operating the mode switch 20 of the operation unit 14. The normal observation mode is automatically selected immediately after the electronic endoscope system 2 is turned on.

  In FIG. 2, the distal end 17 is provided with an observation window 30, an illumination window 31, and the like. In the back of the observation window 30, a CCD 33 for in-subject imaging is disposed via an objective optical system 32. The objective optical system 32 includes a lens group and a prism. The lens group moves along the optical axis in conjunction with the operation of the zoom operation switch 18 (for example, moves between two positions of the tele end and the wide end). 34. By moving the zoom lens 34, it is possible to magnify and non-magnify the region to be observed. The illumination window 31 irradiates the observation site with illumination light from the light source 35 guided by the illumination guide 36 and the light guide 35 disposed in the universal cord 16 and the insertion portion 13.

  The CCD 33 is arranged so that an image of the observation site in the subject via the observation window 30 and the objective optical system 32 is incident on the imaging surface. On the imaging surface, a color filter composed of a plurality of color segments, for example, a primary color filter 37 having a Bayer arrangement (R-red, G-green, B-blue) shown in FIG. 3 is formed.

  Depending on the spectral transmittance of the primary color filter 37 and the spectral sensitivity of the pixel itself, the spectral sensitivity characteristics of the RGB pixels of the CCD 33 are as shown in FIG. The R pixel is sensitive to light having a wavelength near 600 nm, the G pixel is sensitive to light having a wavelength near 550 nm, and the B pixel is sensitive to light having a wavelength near 450 nm. The G pixel is sensitive to light having a wavelength near 405 nm, which is the sensitivity region of the B pixel. In the following description, the sensitivity of the G pixel to light having a wavelength near 405 nm is expressed as a sub-sensitivity region with respect to the main sensitivity region near 550 nm.

  The center wavelength X of the sub-sensitivity region is preferably in the range of 380 nm to 450 nm, and more preferably in the vicinity of 405 nm exemplified above. The sensitivity S ′ at the center wavelength X is preferably 1/5 or more (S ′ ≧ 1 / 5S) of the sensitivity S of the B pixel at the center wavelength X. If the center wavelength X of the sub-sensitivity region and the sensitivity S ′ at the center wavelength X are within the above ranges, the surface blood vessels are more prominent in response to the reflected light from the observation site of the narrowband light having the center wavelength of 405 nm. Therefore, it is possible to sufficiently obtain information necessary for the high resolution processing.

  In FIG. 2, the operation unit 14 is provided with an analog signal processing circuit (hereinafter abbreviated as AFE) 38, a CCD drive circuit 39, and a CPU 40. The AFE 38 includes a correlated double sampling circuit (hereinafter abbreviated as CDS), an automatic gain control circuit (hereinafter abbreviated as AGC), and an analog / digital converter (hereinafter abbreviated as A / D). The CDS performs correlated double sampling processing on the imaging signal output from the CCD 33, and removes reset noise and amplifier noise generated in the CCD 33. The AGC amplifies the image signal from which noise has been removed by CDS with a gain (amplification factor) specified by the processor device 11. The A / D converts the imaging signal amplified by the AGC into a digital signal having a predetermined number of bits. The imaging signal digitized by A / D is input to the image processing circuit 49 of the processor device 11 through a transmission cable.

  The CCD driving circuit 39 generates a driving pulse (vertical / horizontal scanning pulse, electronic shutter pulse, readout pulse, reset pulse, etc.) for the CCD 33 and a synchronization pulse for the AFE 38. The CCD 33 performs an imaging operation in accordance with the drive pulse from the CCD drive circuit 39 and outputs an imaging signal. Each part of the AFE 38 operates based on a synchronization pulse from the CCD drive circuit 39.

  After the electronic endoscope 10 and the processor device 11 are connected, the CPU 40 drives the CCD drive circuit 39 based on an operation start instruction from the CPU 45 of the processor device 11, and the AFE 38 via the CCD drive circuit 39. Adjust the gain of AGC.

  The CPU 45 controls the overall operation of the processor device 11. The CPU 45 is connected to each unit via a data bus, an address bus, and a control line (not shown). The ROM 46 stores various programs (OS, application programs, etc.) and data (graphic data, etc.) for controlling the operation of the processor device 11. The CPU 45 reads necessary programs and data from the ROM 46, develops them in the RAM 47, which is a working memory, and sequentially processes the read programs. Further, the CPU 45 obtains information that changes for each examination, such as examination date and time, character information such as patient and surgeon information, from the operation panel of the processor device 11 or a network such as a LAN (Local Area Network) and stores the information in the RAM 47. .

  The operation unit 48 is an operation panel provided on the housing of the processor device 11 or a known input device such as a mouse or a keyboard. The CPU 45 operates each unit in response to operation signals from the operation unit 48 and the release button, the zoom operation switch 18, the mode change switch 20, and the like in the operation unit 14 of the electronic endoscope 10.

  The image processing circuit 49 performs various types of image processing such as color interpolation, white balance adjustment, gamma correction, image enhancement, image noise reduction, and color conversion on the imaging signal input from the electronic endoscope 10. In color interpolation, for example, the pixel value of the pixel (B and G pixel values if the pixel is an R pixel), and the same color pixel of the eight pixels surrounding the pixel (the surroundings when the B pixel value is interpolated) Linear interpolation is performed to interpolate with the average value of the pixel values of B pixels), and a set of RGB pixel values is generated for each pixel.

  Further, the image processing circuit 49 performs high resolution processing for making the surface blood vessels more prominent when non-enlargement is selected by the zoom operation switch 18 in the special observation mode.

  The display control circuit 50 receives graphic data in the ROM 46 and RAM 47 from the CPU 45. The graphic data includes a display mask that hides the invalid pixel area of the observation image and displays only the effective pixel area, examination date and time, character information such as the patient, the operator, and the currently selected observation mode, a graphical user interface ( GUI; Graphical User Interface). The display control circuit 50 performs various display control processes such as a display mask, character information, GUI superimposition processing, and drawing processing on the display screen of the monitor 19 on the image from the image processing circuit 49.

  The display control circuit 50 has a frame memory that temporarily stores the image from the image processing circuit 49. The display control circuit 50 reads an image from the frame memory and converts the read image into a video signal (component signal, composite signal, etc.) corresponding to the display format of the monitor 19. Thereby, an observation image is displayed on the monitor 19.

  In addition to the above, the processor device 11 includes a compression processing circuit for compressing an image in a predetermined compression format (for example, JPEG format), and the compressed image is stored in a CF card, a magneto-optical disk (MO), a CD- A media I / F for recording on removable media such as R, and a network I / F for controlling transmission of various data with a network such as a LAN are provided. These are connected to the CPU 45 via a data bus or the like.

  The light source device 12 includes a first laser light source 55 that emits blue light having a central wavelength of 445 nm, and a second laser light source 56 that emits blue light having a central wavelength of 405 nm. Condensing lenses 57 and 58, movable diaphragms 59 and 60, and light guides 61 and 62 are arranged on the light emission side of each light source 55 and 56, and the light guides 61 and 62 are connected to a single light via a coupler 63. The guide 35 is connected. The light guide 35 guides light emitted from the light sources 55 and 56 to the illumination window 31. Instead of providing the coupler 63, two light guides may be provided for the light sources 55 and 56, respectively.

  The CPU 64 of the light source device 12 communicates with the CPU 45 of the processor device 11, and controls the turning on / off of each laser beam of each light source 55, 56 and the light amount control by the movable diaphragms 59, 60 via the light source drivers 65, 66. , 56 and each movable diaphragm 59, 60 are performed separately.

  On the light exit side of the light guide 35, a condenser lens 36 and a wavelength conversion member 41 are disposed. The wavelength conversion member 41 has a plurality of types of phosphors that absorb a part of the laser light having a central wavelength of 445 nm from the first laser light source 55 and emit light with excitation from green to yellow. Thus, the blue laser light from the first laser light source 55 and the green to yellow excitation light excited by the laser light are combined to generate white light, that is, normal illumination light. On the other hand, the wavelength conversion member 41 does not react to the laser beam having the center wavelength of 405 nm from the second laser light source 56, and the laser beam passes through the wavelength conversion member 41 and is irradiated from the illumination window 31 to the observation site. The

  When the normal observation mode is selected, the CPU 45 controls the driving of the light source drivers 65 and 66 via the CPU 64 and turns on only the first laser light source 55. The illumination light applied to the site to be observed is only white light. When the special observation mode is selected, the light sources 55 and 56 are turned on at the same time, and white light and narrow-band light are simultaneously irradiated onto the observation site.

  Many capillary blood vessels exist mainly in the vicinity of the mucous membrane surface layer of living tissue. Incidentally, in the middle layer deeper than the surface layer, there are blood vessels that are thicker than capillaries in addition to capillaries, and there are thicker blood vessels in the deep layer. On the other hand, the depth of light penetration into a living tissue depends on the wavelength of the light. In the case of light having a short wavelength such as the central wavelength of 405 nm, the light is only deepened to the vicinity of the surface layer due to absorption and scattering characteristics in the living tissue. Only the reflected light from near the surface layer is observed. Therefore, information on the capillaries on the surface layer can be obtained by irradiating narrow band light having a central wavelength of 405 nm and imaging the reflected light. Since hemoglobin in the blood vessel has a high absorption rate with respect to light of 405 nm, narrow-band light having a central wavelength of 405 nm is absorbed by the blood vessel, and light from living tissue other than the blood vessel returns mainly as reflected light.

Capillary blood vessel information is included in the pixel value b of the B pixel that is sensitive to the reflected light of narrowband light having a center wavelength of 405 nm. On the other hand, information on thick blood vessels in the middle deep layer is included in the pixel values g and r of the G pixel and the R pixel. Since the G pixel has a sub-sensitivity region, the pixel value includes information on capillaries. That is, information on a thick blood vessel in the middle deep layer (component of main sensitivity region, hereinafter also referred to as component of middle deep blood vessel) is g ′, and information on capillary vessel (component of sub sensitivity region, hereinafter also referred to as component of capillary blood vessel). If b ′, the pixel value g of the G pixel is
g = g ′ + b ′ (1)
It can be expressed as.

  The capillaries to be observed in the special observation mode are extremely thin with a size of about 10 μm. For this reason, when a conventional Bayer array color filter in which 1/2 of the G pixel and the number of B pixels are relatively small and the G pixel does not have a sub-sensitivity region is used, The number of B pixels onto which the reflected light, that is, the capillary image is projected is reduced, and the capillary components necessary for imaging are insufficient. For example, as shown by a dotted line in FIG. 3, when a capillary image is projected onto a row of R and G pixels, information on the capillary cannot be obtained at all. This problem becomes prominent when the distance between the site to be observed and the tip 17 is increased without being magnified.

  Therefore, a sub-sensitivity region is provided in the G pixel, which is twice as large as the B and R pixels, so that the pixel value of the G pixel includes capillary information, and the G pixel is regarded as a B pixel. By making a mistake, it compensates for the small number of B pixels. When non-enlargement is selected by the zoom operation switch 18 in the special observation mode, the image processing circuit 49 performs a resolution enhancement process described below. Note that pixel values g, b, r, and the like described below are pixel values after color interpolation.

In the high resolution processing, in addition to the B pixel, a component of the sub sensitivity region included in the pixel value of the G pixel is obtained. As described above, since the pixel value of the G pixel includes not only the information on the thick blood vessel in the middle deep layer but also the information on the capillary blood vessel, the amount corresponding to the information on the thick blood vessel in the middle deep layer is excluded from the pixel value of the G pixel. Capillary blood vessel information can be extracted. Specifically, as shown in FIG. 5, a correlation calculation is performed with the pixel value r of the R pixel having only the information on the thick blood vessel in the middle deep layer. That is, the sub-sensitivity region component b ′ is extracted from the pixel value g of the G pixel by calculating β (g−αr). That is, the image processing circuit 49 functions as an extraction unit. Α is a sensitivity coefficient between the G pixel and the R pixel, and β is a correlation coefficient determined in advance according to the sensitivity ratio between the sub sensitivity areas of the B pixel and the G pixel.
b ′ = β (g−αr) (2)

The image processing circuit 49 further extracts the main sensitivity region component g ′ included in the pixel value g of the G pixel from the expressions (1) and (2).
g ′ = g−b ′ = g (1−β) + αβr (3)
As a result, the pixel value g of the G pixel has a capillary vessel component b ′ = β (g−αr) due to the sub-sensitivity region and a medium-deep blood vessel component g ′ = g (1− (1−)) other than the sub-sensitivity region. β) + αβr, and the G pixel has these two pieces of information. When enlargement is selected by the zoom operation switch 18, only the extraction of the component g ′ = g (1−β) + αβr of the mid-deep blood vessel is performed.

  The middle-layer blood vessel is about 50 μm, the deep-layer blood vessel is about 100 μm, and the middle-layer blood vessel is about 5 to 10 times thicker than the capillary blood vessel. Therefore, even when not enlarged, an image is projected on both a relatively large number of G and R pixels. The Therefore, it can be said that there is a strong correlation between the pixel values of the G and R pixels, and it can be said that the capillary vessel component b 'and the mid-deep blood vessel component g' extracted as a result of the correlation calculation have high accuracy.

  In the normal observation mode, the display control circuit 50 assigns each RGB pixel value generated at each pixel by color interpolation to the RGB channel of the monitor 19 and causes the monitor 19 to display an image substantially equivalent to that observed with the naked eye. . When enlargement is selected in the special observation mode, the pixel value b of the B pixel after color interpolation is assigned to the B channel and the G channel of the monitor 19, and the middle-deep blood vessel component g 'is assigned to the R channel. On the other hand, when non-enlargement is selected, the pixel value b and the capillary vessel component b 'extracted from the pixel value g are assigned to the B channel and the G channel, and the middle-deep blood vessel component g' is assigned to the R channel. In the special observation mode, the R pixel value r is not assigned to any channel. The image generated in this way is displayed on the monitor 19 with the capillaries on the surface layer colored in reddish brown and the other portions in cyan to green, and the capillaries are highlighted.

  When assigning the pixel value b and the capillary component b ′ to the B channel and the G channel when non-enlargement is selected in the special observation mode, the display control circuit 50 multiplies them by an appropriate weighting coefficient, and adds them. Allocate half. As the weighting factor, since the number of G pixels is twice that of B pixels, the capillary component b ′ may be simply doubled, or the pixel value b and the capillary component b ′ may be larger or smaller. It may be changed according to the relationship (in the case of pixel value b >> capillary component b ′, the weighting coefficient applied to the pixel value b is increased).

  Next, the operation of the electronic endoscope system 2 configured as described above will be described. When observing the inside of the subject with the electronic endoscope 10, the operator connects the electronic endoscope 10 and the devices 11 and 12, and turns on the power of the devices 11 and 12. Then, the operation unit 48 is operated to input information about the subject and instruct to start the examination.

  After instructing the start of the examination, the operator inserts the insertion portion 13 into the subject, and illuminates the subject with the illumination light from the light source device 12, while the observation image in the subject by the CCD 33 is displayed on the monitor 19. Observe.

  The imaging signal output from the CCD 33 is subjected to various processing in each part of the AFE 38 and then input to the image processing circuit 49 of the processor device 11. The image processing circuit 49 performs various types of image processing on the input image pickup signal to generate an image. The image processed by the image processing circuit 49 is input to the display control circuit 50. In the display control circuit 50, various display control processes are executed in accordance with the graphic data from the CPU 45. As a result, the observation image is displayed on the monitor 19.

  When an inspection is performed by the electronic endoscope system 2, the observation mode is switched according to the observation target. When inserting the insertion unit 13 into the subject, the normal observation mode is selected, and the insertion operation is performed while observing an image obtained by irradiating the white light to ensure a wide field of view. When a lesion that requires detailed observation is found, the special observation mode is selected, and an image obtained by illuminating the lesion with narrow-band light is observed. Then, if necessary, the zoom operation switch 18 is operated to change the angle of view, or the release button is operated to acquire a still image. When treatment is required for the lesion, various treatment tools are inserted through the forceps channel to perform treatment such as excision of the lesion or medication.

  In the normal observation mode, only the first laser light source 55 is turned on under the instruction of the CPU 40, and white light is emitted from the illumination window 31 to the observation site. On the other hand, when the special observation mode is selected, the second laser light source 56 is turned on in addition to the first laser light source 55. The narrow-band light emitted from the second laser light source 56 is guided to the tip 17 by the light guide 35 and irradiated from the illumination window 31 to the site to be observed.

  When non-enlargement is selected by the zoom operation switch 18 in the special observation mode, the image processing circuit 49 performs color interpolation and then performs a correlation operation with the R pixel value r shown in equations (2) and (3). , G pixel value g is separated into a capillary vessel component b ′ and a mid-deep blood vessel component g ′. When enlargement is selected, only the component g 'of the mid-deep blood vessel is extracted.

  In the normal observation mode, RGB pixel values are assigned to the RGB channels of the monitor 19 by the display control circuit 50, and an observation image substantially equivalent to that observed with the naked eye is displayed on the monitor 19. When enlargement is selected in the special observation mode, the pixel value b of the B pixel is assigned to the B channel and the G channel, and the middle-deep blood vessel component g ′ is assigned to the R channel. When non-enlargement is selected in the special observation mode, the pixel value b and the capillary vessel component b ′ are multiplied by a weighting factor and added to divide by 2 into the B channel and the G channel, and the mid-deep blood vessel component g 'Is assigned to each R channel. The monitor 19 displays an enhanced image in which capillaries are colored reddish brown.

  When non-enlargement is selected, if a capillary component is acquired from only B pixels and an attempt is made to image it, the capillaries are very thin and the number of B pixels is small, so the resolution of the capillary image is reduced. In some cases, a serious influence that leads to a medical error is given to the observation result. In the present invention, a sub-sensitivity region equivalent to a B pixel is provided in a large number of G pixels to acquire a capillary component even in the G pixel. I can do it. After that, the capillary component b 'is extracted from the G pixel value g, and an image in which the capillary is emphasized using this and the B pixel value b is displayed. Therefore, the capillary blood vessel image can be displayed with high resolution, the observation result is also appropriate, and medical errors can be reliably prevented.

  It is only necessary to change the spectral characteristic of the G pixel of the color filter 37, and the extraction of the capillary component b 'is only a simple correlation operation with the R pixel value r, which may increase the size and cost of the apparatus. Absent.

  In addition to the high resolution processing of the above embodiment, it is also possible to make it easier to acquire the capillary component by controlling the intensity of the light emitted from each of the light sources 55 and 56. Specifically, the intensity L2 of the narrow-band light having the center wavelength of 405 nm emitted from the second laser light source 56 is compared with the intensity L1 of the light having the center wavelength of 445 nm emitted from the first laser light source 55 as compared with the magnification. Strengthen when not enlarged. For example, the CPU 64 controls the operations of the light sources 55 and 56 or the movable diaphragms 59 and 60 so that L1: L2 = 1: 1 during enlargement and L1: L2 = 1: 4 during non-enlargement. Increasing the intensity of the narrow band light having a central wavelength of 405 nm emitted from the second laser light source 56 at the time of non-expansion results in the amplification of the B pixel value b and the capillary component b ′, and conversely, the mid-deep blood vessel Since the value of the component g ′ is suppressed, more capillaries can be taken up.

  In addition, when non-enlargement is selected in the special observation mode, the image processing circuit 49 may apply a binning process to the component g ′ of the middle-deep blood vessel. In the binning process, pixel values of a plurality of adjacent pixels (for example, 2 × 2 = 4) are added to obtain a signal representing one pixel. By executing the binning process, it is possible to greatly reduce the data capacity of image data handled in the subsequent processes, and since a plurality of pixels are regarded as one pixel, the apparent sensitivity of the CCD 33 (S / N ratio) is also improved. On the other hand, although the resolution is lowered, the content of g ′ is an image of a middle-deep layer blood vessel having a relatively large size, so that even if the resolution is lowered, it is considered that the influence on the diagnosis is less than in the case of a capillary vessel.

  In the above embodiment, the R pixel value r is not used for image display in the special observation mode, but may be assigned to the R channel of the monitor 19 or the like. In this case, the binning process may also be performed on the R pixel value r to improve the S / N ratio as with the component g ′ of the middle deep blood vessel.

  In the above embodiment, zooming is performed in two stages, but it may be performed in two or more stages. In that case, when the widest end side is selected, or when several steps on the wide end side are selected, the resolution enhancement process and the intensity L2 of the narrowband light having the center wavelength of 405 nm are performed in the same manner as in the non-enlargement of the above embodiment. Change and binning process. It may be configured such that the operator can select up to which stage of zoom the resolution enhancement process, the change of the intensity L2 of the narrowband light having the center wavelength of 405 nm, and the binning process. Regardless of the zoom operation, when the special observation mode is selected, high resolution processing or the like may be performed uniformly. Alternatively, the distance between the tip 17 and the site to be observed may be measured by a distance measuring sensor, and the resolution enhancement processing may be performed when the distance is a fixed distance.

  In the sensitivity characteristic of the G pixel shown in FIG. 4, the sensitivity around the central wavelength of 445 nm of the light emitted from the first laser light source 55 is kept low, but it may have the same sensitivity as the sub-sensitivity region. However, since the reflected light having a wavelength of 445 nm is not so necessary when generating an enhanced image of capillaries, there is no major problem even if the sensitivity is low as shown in FIG.

  The laser light source is exemplified as the light source of the narrow-band light having the center wavelength of 405 nm. However, the white light source and the band-limiting filter that transmits only the light of 405 nm disposed in the optical path may be combined. In addition, a wavelength variable element such as an etalon or a liquid crystal tunable filter may be used.

  It should be noted that the endoscope system according to the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention. For example, the image sensor is not limited to the CCD of the above embodiment, and a CMOS image sensor may be used.

  In the above embodiment, an electronic endoscope having an image pickup device disposed at the tip is illustrated. However, the present invention is not limited to this, and a fiberscope having an image pickup device disposed on the exit surface of the image guide, an image pickup device and an ultrasonic transducer are provided. The present invention can also be applied to other types of endoscopes such as an ultrasonic endoscope built in the distal end portion.

2 Electronic Endoscope System 10 Electronic Endoscope 11 Processor Unit 12 Light Source Unit 18 Zoom Operation Switch 19 Monitor 20 Mode Change Switch 33 CCD
34 Zoom lens 35 Light guide 37 Color filter 40, 45, 64 CPU
41 wavelength conversion member 49 image processing circuit 50 display control circuit 55 first laser light source 56 second laser light source 59, 60 movable diaphragm 65, 66 light source driver

Claims (12)

A first irradiating means for irradiating the observation site of the subject with white light in a broad wavelength band;
A second irradiating means for irradiating the site to be observed with a blue narrow band light whose wavelength band is limited together with white light;
An imaging unit that captures reflected light from an observation site, is provided with RGB primary color filters, the number of G pixels> the number of B pixels, and the G pixels reflect the narrow band light in addition to the green main sensitivity region. An imaging means having a sub-sensitivity region sensitive to light;
Extracting means for extracting a component of the sub-sensitivity region from the pixel value of the G pixel by performing a correlation calculation of the pixel value of the G pixel and the R pixel;
An endoscope system comprising: a display control means for displaying on a monitor an enhanced image of capillaries on the mucosal surface layer based on a pixel value of a B pixel and a component of a sub-sensitivity region extracted by the extraction means. . Has a zoom function,
The extraction means performs extraction of a component of the sub-sensitivity region when non-enlargement is selected by a zoom operation,
2. The display control means, when non-enlargement is selected by a zoom operation, displays an enhanced image on a monitor based on a pixel value of a B pixel and a component of a sub sensitivity region. The endoscope system described in 1. Has a zoom function,
The first irradiating means and the second irradiating means are capable of independently controlling the intensity of white light and narrow band light, respectively, and when non-enlarging is selected in the zoom operation, than when enlarging is selected. The endoscope system according to claim 1 or 2, wherein the first irradiation unit and the second irradiation unit are controlled so that the intensity of the narrow band light becomes stronger than the white light.   The endoscope system according to any one of claims 1 to 3, wherein the extraction unit extracts a component of a main sensitivity region from a pixel value of a G pixel.   The endoscope system according to claim 4, further comprising a binning processing unit that performs a binning process on a component of the main sensitivity region extracted by the extraction unit.   6. The display control means according to claim 4, wherein the pixel value of the B pixel and the component of the sub-sensitivity area are assigned to the B and G channels of the monitor, and the component of the main sensitivity area is assigned to the R channel of the monitor. The endoscope system described.   The endoscope system according to claim 1, wherein the extraction unit performs extraction from a pixel value of a G pixel after pixel interpolation.   The sub-sensitivity region has a center wavelength at a wavelength of 380 nm to 450 nm, and the sensitivity at the center wavelength is 1/5 or more of the sensitivity of the B pixel at the center wavelength. The endoscope system according to Crab. The first irradiation means includes a laser light source that emits blue light;
A wavelength conversion member that emits light from green to yellow by blue light;
The endoscope system according to any one of claims 1 to 8, wherein white light is obtained by mixing blue light and excitation light emission.   The endoscope system according to any one of claims 1 to 9, wherein the second irradiation unit includes a laser light source that emits a blue narrow-band light having a center wavelength of 405 nm.   The endoscope system according to any one of claims 1 to 10, wherein the primary color filters have a Bayer arrangement. Irradiate the observation site of the subject with white light in a broad wavelength band and blue narrow-band light with a limited wavelength band,
The reflected light is provided with RGB primary color filters, the number of G pixels> the number of B pixels, and the G pixels have a sub sensitivity region that is sensitive to the reflected light of the narrow band light in addition to the green main sensitivity region. Image by means,
By performing the correlation calculation of the pixel values of the G pixel and the R pixel, the component of the sub sensitivity region is extracted from the pixel value of the G pixel,
A method for displaying an enhanced image of a capillary on a mucosal surface layer, wherein an enhanced image of the capillary on the surface of the mucosa based on the pixel value of the B pixel and the extracted component of the sub-sensitivity region is displayed on a monitor.

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