JP2012170640A - 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 first irradiation operation of irradiating narrow band light at maximum intensity (first intensity) and a second irradiation operation of irradiating narrow band light at normal intensity (second intensity) are alternately repeated in units of storage periods of a CCD 33 when non-enlargement is selected by a zoom operating switch. An image processing circuit 49 extracts a capillary component b' of the mucous membrane surface layer from a G pixel value g obtained in the first irradiation operation by correlative operation to an R pixel value r obtained in the first irradiation operation. A display control circuit 50 allocates a B pixel value b obtained in the second irradiation operation and the extracted component b' to B, G channels of a monitor 19 and a G pixel value g obtained in the second irradiation operation to an R channel respectively. An emphasized image of the capillary colored in reddish brown 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. Second irradiating means for irradiating the observation site with a narrow band of light, imaging means having RGB pixels and imaging reflected light from the observation site, and operation control for controlling the operation of the second irradiating means A first irradiating operation for irradiating narrowband light with a first intensity at a predetermined light intensity, and narrowband light with a second intensity lower than the first intensity at which the pixel value of the B pixel is not saturated. Operation control means for causing the second irradiation means to alternately repeat the second irradiation operation for irradiation in units of the accumulation period of the imaging means, and a correlation calculation of the pixel values of the G pixel and the R pixel obtained by the first irradiation operation By performing the G image from the pixel value of the G pixel obtained in the first irradiation operation. Extraction means for extracting a component of a sensitivity region sensitive to narrow band light, pixel value of B pixel obtained by the second irradiation operation, and enhancement of capillaries on the mucous membrane surface layer based on the component extracted by the extraction means And display control means for displaying an image on a monitor.

  When the zoom function is provided, when non-enlargement is selected in the zoom operation, the control unit causes the second irradiation unit to perform the first and second irradiation operations, and the extraction unit performs component extraction. The display control means displays on the monitor an emphasized image based on the pixel value of the B pixel obtained by the second irradiation operation and the component extracted by the extraction means. Note that zooming in / out may be performed in two stages or more. In the case of multi-stage zoom, the B pixel obtained by the first, second irradiation operation, component extraction, and second irradiation operation when the widest end side is selected or when several steps on the wide end side are selected. The emphasized image is displayed based on the pixel value and the component extracted by the extracting means.

  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 by the zoom operation, the second irradiation operation is configured so that the intensity of the narrow band light is higher than that of the white light than when the enlargement is selected. One irradiation means and the second irradiation means are controlled. 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.

  You may provide the binning process means which performs a binning process with respect to the pixel value of G pixel obtained by 2nd irradiation operation | movement. The binning processing means may perform a binning process on the pixel value of the R pixel obtained by the second irradiation operation.

  The display control means monitors the pixel value of the B pixel obtained by the second irradiation operation and the component value extracted by the extraction means to the B and G channels of the monitor and the pixel value of the G pixel obtained by the second irradiation operation. Assigned to each R channel.

  The extraction unit performs extraction from the pixel value of the G pixel obtained by the first irradiation operation after pixel interpolation.

  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.

  In the method for displaying an emphasis image of capillaries on the surface layer of the mucosa of the present invention, a white light in a broad wavelength band and a blue narrow band light in which the wavelength band is limited are irradiated to an observation site of a subject, and the reflected light is imaged. This is a method of displaying an enhanced image of capillaries on the mucous membrane surface layer based on the pixel values of each of the RGB pixels obtained thereby, and irradiating narrowband light at a first intensity with a predetermined light quantity The first irradiation operation to be performed and the second irradiation operation to irradiate the narrowband light at the second intensity lower than the first intensity at which the pixel value of the B pixel is not saturated are alternately repeated for each accumulation period of the imaging unit, By performing a correlation calculation of the pixel values of the G pixel and the R pixel obtained by the first irradiation operation, the component of the sensitivity region in which the G pixel is sensitive to narrowband light from the pixel value of the G pixel obtained by the first irradiation operation. Extract and extract the pixel value of the B pixel obtained by the second irradiation operation and the extraction means. And displaying the enhanced image of the mucosa surface layer of the capillaries in which the ingredients based on the monitor.

  According to the present invention, narrow band light is irradiated with a first intensity with a predetermined light amount, and a component of a sensitivity region in which the G pixel is sensitive to narrow band light is extracted from the pixel value of the G pixel obtained thereby. Then, since the enhanced image of the capillaries on the mucosal surface layer is displayed based on this, it is possible to provide a high-resolution image of the capillaries on the mucosal surface layer 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 timing chart which shows the relationship between CCD operation | movement and the intensity | strength of white light and narrowband light. It is a figure which shows the high resolution process. It is a figure which shows the display method to the monitor using the image data Da obtained by irradiating narrowband light with the maximum intensity | strength, and the image data Db obtained by irradiating narrowband light with normal intensity | strength.

  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 in the vicinity of 405 nm, which is the sensitivity region of the B pixel.

  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. As described with reference to FIG. 4, since the G pixel has a slight sensitivity even at a wavelength of 405 nm, the pixel value includes information on capillaries. That is, assuming that the information on the thick blood vessel in the middle deep layer (hereinafter also referred to as the component of the middle deep blood vessel) is g ′ and the information on the capillary vessel (hereinafter also referred to as the component of the capillary vessel) is b ′, the pixel value g of the G pixel is ,
g = g ′ + b ′ (1)
It can be expressed as. However, the component b ′ of the capillary is extremely small compared to the component g ′ of the mid-deep blood vessel.

  The capillaries to be observed in the special observation mode are extremely thin with a size of about 10 μm. For this reason, when the color filter 37 having a Bayer arrangement in which the number of G pixels is 1/2 and the number of B pixels is relatively small, reflected light of narrow band light having a center wavelength of 405 nm, that is, an image of a capillary vessel is projected. The number of B pixels 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, when non-enlargement is selected in the special observation mode, as shown in FIG. 5, the operations of the second laser light source 56 and the movable diaphragm 60 are controlled to narrow-band light at the maximum intensity (first intensity). , The pixel value of the G pixel is made to include more capillary information b ′, and the fact that the G pixel is regarded as a B pixel compensates for the small number of B pixels. Subsequently, the operations of the movable diaphragm 60 and the second laser light source 56 are controlled so that the intensity of the narrow-band light is equal to (second intensity) when enlargement is selected in the special observation mode. Then, the operation of irradiating narrow band light at the maximum intensity (first irradiation operation) and the operation of irradiating narrow band light at the normal intensity (second irradiation operation) are repeated for each accumulation period of the CCD 33. After that, the image processing circuit 49 performs a resolution enhancement process described below. Note that image data obtained by irradiating narrow-band light at the maximum intensity is Da, and image data obtained by irradiating narrow-band light at normal intensity is Db. Also, the pixel values g, b, r, etc. described below are all pixel values after color interpolation.

In order to irradiate narrow band light with the maximum intensity, the B pixel value b of the image data Da is close to the maximum value or is saturated, but the capillary component b ′ of the G pixel value g irradiates the narrow band light with normal intensity. More than the case. Therefore, in the high resolution processing, a capillary component b ′ included in the G pixel value g of the image data Da is obtained. In order to obtain the capillary vessel information b ′ from the G pixel value g of the image data Da, an amount corresponding to the middle-deep thick blood vessel information g ′ may be excluded from the G pixel value g. Specifically, as shown in FIG. 6, correlation calculation is performed with the pixel value r of the R pixel of the image data Da having only the information on the thick blood vessels in the middle deep layer. That is, the capillary 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 B pixel and the G pixel at a wavelength of 405 nm.
b ′ = β (g−αr) (2)

  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 Accordingly, it can be said that there is a strong correlation between the pixel values of the G and R pixels, and the capillary component b 'extracted as a result of the correlation calculation is also highly accurate.

  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 G pixel value g is assigned to the R channel. On the other hand, when non-enlargement is selected, the B pixel value b of the image data Db and the capillary component b ′ extracted from the G pixel value g of the image data Da are set to the B channel and the G channel, and the G of the image data Db is set. Pixel value g is assigned to each 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.

  As conceptually shown in FIG. 7, the display control circuit 50 displays an image using a set of image data Da and Db in which frames are adjacent. Each of the image data Da and Db is used for display on the monitor 19 twice for the previous frame and the next frame. For this reason, the image display frame rate is the same as when enlargement is selected in the normal observation mode and the special observation mode.

  The display control circuit 50 outputs the capillary component b ′ extracted from the B pixel value b of the image data Db and the G pixel value g of the image data Da when the non-enlargement is selected in the special observation mode. When assigning to, multiply these by multiplying them by an appropriate weighting factor, and halve them. 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 operations of the second laser light source 56 and the movable diaphragm 60 are controlled, and the operation of irradiating the narrowband light with the maximum intensity and the narrowband light with the normal intensity are performed. Is repeated for each accumulation period of the CCD 33. In the image processing circuit 49, after the color interpolation, the G pixel value g of the image data Da obtained by irradiating the narrow band light with the maximum intensity by the correlation calculation with the R pixel value r shown in Expression (2). Capillary component b ′ is extracted from When enlargement is selected, narrowband light is irradiated with normal intensity.

  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 G pixel value g is assigned to the R channel. When non-enlargement is selected in the special observation mode, the B pixel value b of the image data Db obtained by irradiating narrowband light with normal intensity and the image data obtained by irradiating narrowband light with maximum intensity Capillary component b 'extracted from G pixel value g of Da is multiplied by a weighting factor and added, and the result divided by 2 is assigned to B channel and G channel, and G pixel value g of image data Db is assigned to R channel. It is done. The monitor 19 displays an enhanced image in which capillaries are colored reddish brown.

  When non-enlargement is selected, if the capillary component is acquired from only the B pixel and an attempt is made to image it, the capillary image is 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. However, in the present invention, by irradiating narrowband light with the maximum intensity, it is possible to acquire a capillary component even with a large number of G pixels. Like that. 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 irradiate narrow-band light with the maximum intensity, and the extraction of the capillary component b 'is only a simple correlation calculation with the R pixel value r, so there is no concern about the increase in size and cost of the apparatus.

  Note that when non-magnification is selected in the special observation mode, narrow-band light is alternately radiated at the same normal intensity and maximum intensity as when magnified, but lower than the maximum intensity and slightly stronger than the normal intensity. It is also possible to make it easier to obtain the capillary component by irradiating the narrow-band light. 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. If the intensity of the narrow band light having the center wavelength of 405 nm emitted from the second laser light source 56 at the time of non-enlarging is increased, as a result, the value of the B pixel value b of the image data Db is amplified, and conversely, the value of the G pixel value g Is suppressed, and 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 G pixel value g of the image data Db. 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. Therefore, even if the resolution is lowered, it is considered that the influence on diagnosis is less than that in the case of capillary blood vessels.

  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 G pixel value g.

  The first intensity in the first irradiation operation does not have to be the maximum intensity in the above-described embodiment, and may be an intensity at which the B pixel value b is saturated. If the G pixel is sensitive enough to reflect the reflected light from the observation site of the narrow band light having the center wavelength of 405 nm, the G pixel can sufficiently obtain information necessary for high resolution processing for making the surface blood vessels more prominent. Good.

  In the above embodiment, zooming is performed in two stages, but it may be performed in two or more stages. In that case, when selecting the widest end side, or when selecting several steps on the wide end side, the first and second irradiation operations, the high resolution processing, the center wavelength, as in the non-enlargement of the above embodiment Changing the intensity L2 of the narrow-band light of 405 nm and binning processing are performed. It may be configured so that the operator can select up to which stage of zooming the first and second irradiation operations, 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.

  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 (9)

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 means having RGB pixels and imaging reflected light from a site to be observed;
Operation control means for controlling the operation of the second irradiation means, the first irradiation operation for irradiating the narrow band light with the first intensity at a predetermined light amount, and the first intensity at which the pixel value of the B pixel is not saturated. An operation control unit that causes the second irradiation unit to alternately repeat the second irradiation operation of irradiating the narrowband light at a second intensity lower than the second irradiation unit in units of the accumulation period of the imaging unit;
By performing a correlation calculation of the pixel values of the G pixel and the R pixel obtained by the first irradiation operation, the component of the sensitivity region in which the G pixel is sensitive to narrowband light from the pixel value of the G pixel obtained by the first irradiation operation Extracting means for extracting;
Display control means for displaying on the monitor an enhanced image of capillaries on the mucosal surface layer based on the pixel value of the B pixel obtained by the second irradiation operation and the component extracted by the extraction means. Endoscopic system. Has a zoom function,
When non-enlargement is selected in the zoom operation, the control means causes the second irradiation means to perform the first and second irradiation operations,
The extraction means extracts components;
The display control means performs display on a monitor of an emphasized image based on the pixel value of the B pixel obtained by the second irradiation operation and the component extracted by the extraction means. Endoscope system. Has a zoom function,
The first irradiating means and the second irradiating means can independently control the intensity of white light and narrow band light, and when non-enlarging is selected in the zoom operation, enlargement is performed in the second irradiating operation. The endoscope 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 is stronger than that of the white light when selected. system.   The endoscope system according to any one of claims 1 to 3, further comprising a binning processing unit that performs a binning process on a pixel value of the G pixel obtained by the second irradiation operation.   The display control means monitors the pixel value of the B pixel obtained by the second irradiation operation and the component value extracted by the extraction means to the B and G channels of the monitor and the pixel value of the G pixel obtained by the second irradiation operation. The endoscope system according to any one of claims 1 to 4, wherein the endoscope system is assigned to each of the R channels.   The endoscope system according to any one of claims 1 to 6, wherein the extraction unit performs extraction from a pixel value of a G pixel obtained by a first irradiation operation after pixel interpolation. 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 6, wherein white light is obtained by mixing blue light and excitation light emission.   The endoscope system according to any one of claims 1 to 7, wherein the second irradiation unit includes a laser light source that emits blue narrow-band light having a center wavelength of 405 nm. White light in a broad wavelength band and blue narrow band light in which the wavelength band is limited are irradiated onto the observation site of the subject, and the reflected light is imaged by the imaging means, and the pixels of the RGB pixels obtained thereby A method for displaying an enhanced image of capillaries on the surface of the mucous membrane based on values,
A first irradiation operation for irradiating narrowband light with a first intensity at a predetermined light amount, and a second irradiation for irradiating narrowband light with a second intensity lower than the first intensity at which the pixel value of the B pixel is not saturated. The irradiation operation is repeated alternately in units of the accumulation period of the imaging means,
By performing a correlation calculation of the pixel values of the G pixel and the R pixel obtained by the first irradiation operation, the component of the sensitivity region in which the G pixel is sensitive to narrowband light from the pixel value of the G pixel obtained by the first irradiation operation Extract and
Emphasis on capillaries on the mucosal surface layer, characterized in that an emphasis image of the capillaries on the mucosal surface layer based on the pixel value of the B pixel obtained by the second irradiation operation and the component extracted by the extracting means is displayed on the monitor Image display method.

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