Endoscope light quantity control device and endoscope light quantity control method

Abstract

This endoscope light quantity control device controls a light quantity value on the basis of an image acquired by an endoscope. The endoscope light quantity control device includes a luminance evaluation unit that calculates a luminance evaluation value for the whole image and a luminance evaluation value for the periphery of the image, and a light quantity control unit that controls the light quantity value on the basis of larger luminance evaluation value of the whole luminance evaluation value and the peripheral luminance evaluation value.

Description

Endoscope light intensity control device and endoscope light intensity control method

[0001] The present invention relates to an endoscope light amount control device and an endoscope light amount control method for controlling the amount of light supplied to an endoscope.

[0002] Endoscope systems have been widely used in the medical and industrial fields and include an endoscope with an imaging unit that captures an image of a subject, a video processor that generates an endoscopic image from an image signal captured by the endoscope, a light source device that generates illumination light that is applied from the distal end of the endoscope to the subject under observation, and a monitor that displays the endoscopic image generated by the video processor.

[0003] In such an endoscope system, the amount of illumination light emitted by the light source device is automatically adjusted according to the brightness of the endoscope image generated based on the image capture signal. For example, Japanese Patent Application Laid-Open No. 2022-9921 discloses an illumination control system that controls the amount of light based on the average luminance value of the entire image.

[0004] For example, when observing biological tissue from the front, the brightness is approximately the same across the entire image, so there is no problem even if the amount of light is controlled based on the average brightness value across the entire image.

[0005] On the other hand, when observing the inside of a lumen, the center of the image is dark and the periphery of the image is bright. In this case, the average brightness value of the entire image is low, so the light intensity is controlled to be increased based on the average brightness value of the entire image. In other words, if the light intensity is controlled based on the average brightness value of the entire image, it may not be possible to control the light intensity to an appropriate level depending on the observation area.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an endoscope light intensity control device and an endoscope light intensity control method that can control the light intensity to an appropriate level regardless of the observation area.

[0007] An endoscopic light intensity control device according to one aspect of the present invention is an endoscopic light intensity control device that controls a light intensity value based on an image acquired by an endoscope, and includes a brightness evaluation unit that calculates an overall brightness evaluation value of the image and a brightness evaluation value of the periphery of the image, and a light intensity control unit that controls the light intensity value based on the larger brightness evaluation value of the overall brightness evaluation value and the periphery brightness evaluation value.

[0008] An endoscopic light intensity control method according to one aspect of the present invention is an endoscopic light intensity control method that controls a light intensity value based on an image acquired by an endoscope, in which an overall brightness evaluation value of the image and a brightness evaluation value of the periphery of the image are calculated, and the light intensity value is controlled based on the larger brightness evaluation value of the overall brightness evaluation value and the periphery brightness evaluation value.

[0009] FIG. 1 is a diagram illustrating an example of the functional configuration of an endoscopic system according to a first embodiment. FIG. 2 is a schematic diagram illustrating an endoscopic image and the state of observation when observing biological tissue. FIG. 3 is a schematic diagram illustrating an endoscopic image and the state of observation when observing a lumen. FIG. 4 is a diagram illustrating an example of a state in which an area of ​​an endoscopic image is divided. FIG. 5 is a schematic diagram illustrating a state in which biological tissue is observed at an angle. FIG. 6 is a diagram illustrating an example of a state in which the peripheral area of ​​an endoscopic image is divided into multiple areas. FIG. 7 is a schematic diagram illustrating a peripheral area of ​​an endoscopic image. FIG. 8 is a diagram illustrating an example of the relationship between the contrast ratio of the brightest part and a correction value C. FIG. 9 is a diagram illustrating an example of the functional configuration of an endoscopic system according to a fourth embodiment. FIG. 10 is a diagram illustrating the relationship between a reduction coefficient S and a brightness evaluation value L.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, identical or corresponding elements are appropriately designated by the same reference numerals. It should be noted that the drawings are schematic, and the length relationships, length ratios, and quantities of elements within a single drawing may differ from reality in order to simplify the description. Furthermore, there may be portions in which the length relationships and ratios differ between multiple drawings.

[0011] First Embodiment Fig. 1 is a diagram showing an example of the functional configuration of an endoscope system according to a first embodiment. As shown in Fig. 1, an endoscope system 100 includes an endoscope 1, a video processor 2, a light source device 3, and a monitor 4. The video processor 2 and the light source device 3 constitute an endoscope light intensity control device according to this embodiment.

[0012] The endoscope 1 includes an imaging lens 11 , an imaging element 12 , an A / D converter 13 , a light guide 14 , and an illumination lens 15 .

[0013] The imaging lens 11 includes one or more lenses and forms an optical image of the subject on the imaging element 12. The optical image formed on the imaging element 12 includes images of one or more parts of the subject's multiple parts.

[0014] The imaging element 12 photoelectrically converts (captures) an optical image of the subject and generates an analog image signal related to the endoscopic image. The imaging lens 11 and the imaging element 12 constitute an imaging system that captures images and acquires the endoscopic image.

[0015] The A / D converter 13 converts the analog imaging signal into a digital imaging signal. The endoscopic image corresponding to the digital imaging signal is transmitted from the endoscope 1 to the video processor 2. Although the example in which the A / D converter 13 is provided within the endoscope 1 has been shown here, it may also be provided within the video processor 2. Furthermore, the imaging element 12 may be a digital imaging element having the functionality of the A / D converter 13.

[0016] The light guide 14 transmits the illumination light supplied from the light source device 3 to the illumination lens 15. The illumination lens 15 irradiates the subject with the illumination light transmitted by the light guide 14. The illumination lens 15 and the imaging system (imaging lens 11 and imaging element 12) are disposed at the distal end of the insertion section 16 (see FIGS. 2 and 3 ) of the endoscope 1.

[0017] The video processor 2 includes an image receiving section 21 , an image processing section 22 , a monitor output section 23 , and a brightness evaluation section 24 .

[0018] The image receiving unit 21 receives an endoscopic image from the endoscope 1 and outputs it to the image processing unit 22 .

[0019] The image processing unit 22 performs image processing for image adjustment (image construction) on the endoscopic image input from the image receiving unit 21. The image processing performed by the image processing unit 22 may include, for example, demosaicing, gain adjustment, white balance adjustment, gamma correction, noise reduction, contrast enhancement, color change, etc. Parameters for some of the processes performed by the image processing unit 22, such as contrast enhancement and color change, may be set by the user.

[0020] The image processing unit 22 outputs the processed endoscopic image to the monitor output unit 23 and the brightness evaluation unit 24 .

[0021] The monitor output unit 23 outputs the endoscopic image input from the image processing unit 22 to the monitor 5. As a result, the endoscopic image captured by the endoscope 1 is displayed on the monitor 5.

[0022] Fig. 2 is a schematic diagram showing an endoscopic image and the state of observation when observing biological tissue, and Fig. 3 is a schematic diagram showing an endoscopic image and the state of observation when observing a lumen.

[0023] 2, when biological tissue 101 is observed from the front with the endoscope 1, the endoscopic image 102 has approximately the same luminance (almost uniform brightness). In other words, when biological tissue is observed from the front, the luminance is approximately the same across the entire image, so there is no problem with controlling the amount of light based on the average luminance value across the entire image.

[0024] 3, when a lumen 103 is observed with the endoscope 1, the endoscopic image 104 has a dark center and a bright periphery. In this case, the average luminance value of the entire image is low, so the light amount is controlled to be increased based on the average luminance value of the entire image. In other words, if the light amount is controlled based on the average luminance of the entire image, the periphery of the endoscopic image 104 becomes too bright, and it is not possible to control the light amount to an appropriate level.

[0025] Therefore, in this embodiment, an endoscope light amount control device constituted by the video processor 2 and the light source device 3 controls the light amount to an appropriate amount regardless of the observation area.

[0026] FIG. 4 is a diagram showing an example of the state in which the regions of an endoscopic image have been divided. As described above, the endoscopic image is input to the brightness evaluation unit 24 from the image processing unit 22. As shown in FIG. 4, the brightness evaluation unit 24 divides the endoscopic image into a peripheral region A1 that includes at least the periphery of the endoscopic image and a central region A2 that includes at least the center. The brightness evaluation unit 24 then calculates the average value of the brightness values ​​of the entire endoscopic image (peripheral region A1 and central region A2) (hereinafter referred to as the brightness evaluation value Lw). The brightness evaluation unit 24 also calculates the average value of the brightness values ​​of the periphery of the endoscopic image (peripheral region A1) (hereinafter referred to as the brightness evaluation value Ls). The brightness evaluation unit 24 outputs the calculated brightness evaluation value Lw of the entire endoscopic image and the brightness evaluation value Ls of the periphery of the endoscopic image to the light source device 3.

[0027] The light source device 3 has a light intensity control unit 31 and a light source 32. The light intensity control unit 31 controls the light intensity of the light source 32 based on the overall luminance evaluation value Lw of the endoscopic image and the peripheral luminance evaluation value Ls of the endoscopic image input from the luminance evaluation unit 24.

[0028] Specifically, the light intensity control unit 31 compares the overall brightness evaluation value Lw of the endoscopic image with the brightness evaluation value Ls of the periphery of the endoscopic image, and if the brightness evaluation value Lw is greater than or equal to the brightness evaluation value Ls (Lw≧Ls), it controls the light intensity of the light source 32 based on the overall brightness evaluation value Lw of the endoscopic image.

[0029] On the other hand, the light intensity control unit 31 compares the overall brightness evaluation value Lw of the endoscopic image with the brightness evaluation value Ls of the periphery of the endoscopic image, and if the brightness evaluation value Ls is higher than the brightness evaluation value Lw (Lw<Ls), controls the light intensity of the light source 32 based on the brightness evaluation value Ls of the periphery of the endoscopic image.

[0030] The light source 32 is a light-emitting device such as an LED (Light Emitting Diode) light source, a laser light source, or a xenon light source. The light source 32 emits illumination light using the light-emitting device based on the control of the light quantity control unit 31. The light source 32 is configured by combining one or more types of light-emitting devices such as an LED light source, a laser light source, or a xenon light source. However, the light-emitting device is not limited to the examples given here, and any known technology can be used as appropriate.

[0031] Illumination light emitted from the light source 32 is incident on the incident end of the light guide 14. The light guide 14 transmits the illumination light incident from the incident end to the exit end. The transmitted illumination light is emitted from the exit end of the light guide 14 and is irradiated onto the subject by the illumination lens 15.

[0032] As described above, in this embodiment, the brightness evaluation unit 24 calculates a brightness evaluation value Lw of the entire endoscopic image and a brightness evaluation value Ls of the periphery of the endoscopic image. Then, when the brightness evaluation value Lw is equal to or greater than the brightness evaluation value Ls (Lw≧Ls), the light intensity control unit 31 controls the light intensity of the light source 32 based on the brightness evaluation value Lw of the entire endoscopic image. On the other hand, when the brightness evaluation value Ls is higher than the brightness evaluation value Lw (Lw<Ls), the light intensity control unit 31 controls the light intensity of the light source 32 based on the brightness evaluation value Ls of the periphery of the endoscopic image.

[0033] As a result, the endoscope light intensity control device of this embodiment prevents the periphery of the endoscope image from being too bright even when observing a lumen, and can control the light intensity to an appropriate level regardless of the observation area.

[0034] Second Embodiment Next, a second embodiment will be described. Fig. 5 is a schematic diagram showing a state in which biological tissue is being observed at an angle.

[0035] 5, when observing tissue 105 at an angle, the upper side of the peripheral region of the endoscopic image becomes brighter and the lower side becomes darker, for example. In such a state, if the light intensity of the light source 32 is controlled based on the overall brightness evaluation value Lw of the endoscopic image or the peripheral brightness evaluation value Ls of the endoscopic image, it may not be possible to control the light intensity to an appropriate level.

[0036] In the second embodiment, an endoscope light intensity control device that can set an appropriate light intensity even when observing tissue 105 in an oblique position will be described.

[0037] 6 is a diagram showing an example of a state in which the peripheral region of an endoscopic image is divided into multiple regions. The brightness evaluation unit 24 calculates a brightness evaluation value Lw of the entire endoscopic image 106. The brightness evaluation unit 24 also divides the peripheral region of the endoscopic image 106 into multiple regions and calculates a brightness evaluation value for each region.

[0038] 6, the brightness evaluation unit 24 divides the area around the endoscopic image 106 into 10 areas and calculates brightness evaluation values ​​Ls1 to Ls10 for each area. The brightness evaluation unit 24 outputs the calculated overall brightness evaluation value Lw and brightness evaluation values ​​Ls1 to Ls10 for the endoscopic image 106 to the light intensity control unit 31. Note that although the area around the endoscopic image 106 is divided into 10 areas, the number of divisions is not limited to 10 and may be 9 or less, or 11 or more.

[0039] The light intensity control unit 31 compares the overall brightness evaluation value Lw of the endoscopic image 106 with the brightness evaluation values ​​Ls1 to Ls10 of the periphery of the divided endoscopic image 106, and controls the light intensity of the light source 32 based on the largest brightness evaluation value.

[0040] As a result, with the endoscope light intensity control device of this embodiment, even when observing oblique tissue 105, the periphery of the endoscopic image 106 does not become too bright, and an appropriate light intensity can be set.

[0041] (Modification) Next, a modification of the second embodiment will be described. For example, when light is reflected by a treatment tool such as forceps and a certain region becomes bright, controlling the light intensity based on the luminance evaluation value of this region may result in an inability to control the brightness to an appropriate level. Therefore, the contrast ratio of adjacent divided regions may be calculated, and the light intensity of the light source 32 may be controlled based on the calculation result.

[0042] 7 is a schematic diagram showing the peripheral region of an endoscopic image. Given that the brightness evaluation value Lsmax of the brightest part is the brightness evaluation value of the brightest part, the brightness evaluation unit 24 calculates the contrast ratio between two regions adjacent to the brightest part. Then, the brightness evaluation value Lsmax of the brightest part is multiplied by a correction value C corresponding to the calculated contrast ratio. Specifically, the brightness evaluation value Ls of the periphery of the endoscopic image is calculated by multiplying the brightness evaluation value Lsmax of the brightest part by the correction value C.

[0043] 8 is a diagram showing an example of the relationship between the contrast ratio of the brightest part and the correction value C. When the contrast ratio of the brightest part is C1 or less, the correction value C is set to 1. When the contrast ratio of the brightest part is greater than C1 and less than C2, the correction value C is gradually decreased. When the contrast ratio of the brightest part is greater than C2, the correction value C is kept constant at a value less than 1.

[0044] When the endoscope 1 approaches the biological tissue and a certain area becomes bright, the contrast ratio calculated for two areas close to the brightest area will be small. On the other hand, when a part of the area where the forceps reflect the illumination light becomes bright, the contrast ratio calculated for two areas close to the brightest area will be large.

[0045] Therefore, when the contrast ratio between two areas adjacent to the brightest area increases, the brightness evaluation value Lsmax of the brightest area is corrected to be lower by the correction value C. As a result, the light amount is no longer controlled by the brightness evaluation value Lsmax of light reflected by the forceps, and the light amount can be controlled to an appropriate level.

[0046] According to this modification, the contrast ratio is calculated for two areas adjacent to the brightest area, and a correction value C is obtained according to the contrast ratio to calculate the brightness evaluation value Ls. Therefore, even when some areas become bright, it is possible to distinguish whether the bright areas are due to the lighting approaching the biological tissue or to light being reflected by the forceps.

[0047] Third Embodiment Next, a third embodiment will be described. For example, when tissue is dyed blue with indigo carmine or the like, the light absorption rate increases, so it is not preferable to irradiate the tissue with strong light.

[0048] Therefore, the luminance evaluation unit 24 multiplies the R (red), G (green), and B (blue) signals that make up the luminance evaluation values ​​Lw and Ls by coefficients to calculate the luminance evaluation values ​​Lw and Ls. If the luminance evaluation values ​​Lw and Ls are the luminance evaluation value L, then L = a × R + b × G + c × B, where a < b < c. In other words, the luminance evaluation unit 24 adjusts the evaluation value of B (blue) so that it is higher than the evaluation values ​​of R (red) and G (green).

[0049] The light intensity control unit 31 compares the luminance evaluation value Lw with the luminance evaluation value Ls, and controls the light intensity of the light source 32 using the larger luminance evaluation value, as in the first embodiment. As a result, the endoscope light intensity control device of this embodiment can control the light intensity to an appropriate level even for a stained image.

[0050] (Fourth embodiment) Next, a fourth embodiment will be described. Fig. 9 is a diagram showing an example of the functional configuration of an endoscope system according to the fourth embodiment. In Fig. 9, the same components as those in Fig. 1 are denoted by the same reference numerals, and their description will be omitted.

[0051] The endoscope system 100A is configured using a video processor 2A instead of the video processor 2 in Fig. 1. The video processor 2A is configured by adding an autofocus control unit (hereinafter referred to as an AF control unit) 25, a light intensity upper limit value calculation unit 26, a reduction coefficient calculation unit 27, and a multiplier 28 to the video processor 2 in Fig. 1.

[0052] The AF control unit 25 controls the focus state of the imaging lens 11 by controlling the driving of a focus lens included in the imaging lens 11. The AF control unit 25 also outputs information about the distance to the subject to the upper light amount limit calculation unit 26.

[0053] The light amount upper limit calculation unit 26 outputs the upper limit of light amount control (upper limit light amount M1) to the multiplier 28 based on information about the distance to the subject.

[0054] As in the first embodiment described above, the brightness evaluation unit 24 calculates a brightness evaluation value Lw of the entire endoscopic image and a brightness evaluation value Ls of the periphery of the endoscopic image, and outputs them to the light quantity control unit 31. In addition, the brightness evaluation unit 24 outputs the calculated brightness evaluation value Lw of the entire endoscopic image and the brightness evaluation value Ls of the periphery of the endoscopic image to the reduction coefficient calculation unit 27.

[0055] The reduction coefficient calculation unit 27 calculates a reduction coefficient S of light energy from the luminance evaluation value Lw and the luminance evaluation value Ls.

[0056] 10 is a diagram showing the relationship between the reduction coefficient S and the luminance evaluation value L. As shown in Fig. 10, when the luminance evaluation value Lw and the luminance evaluation value Ls are represented by the luminance evaluation value L, the reduction coefficient calculation unit 27 reduces the reduction coefficient S of the light energy as the luminance evaluation value L increases.

[0057] Specifically, when the luminance evaluation value L is equal to or less than L1, the reduction coefficient calculation unit 27 sets the light energy reduction coefficient S to 1. When the luminance evaluation value L is greater than L1 and equal to or less than L2, the reduction coefficient calculation unit 27 gradually decreases the reduction coefficient S. When the luminance evaluation value L is greater than L2, the reduction coefficient calculation unit 27 sets the light energy reduction coefficient S to 0.5. The reduction coefficient calculation unit 27 outputs the calculated light energy reduction coefficient S to the multiplier 28.

[0058] The multiplier 28 calculates the upper limit light intensity M2 by multiplying the upper limit light intensity M1 calculated by the upper limit light intensity value calculation unit 26 by the light energy reduction coefficient S calculated by the reduction coefficient calculation unit 27, and outputs the upper limit light intensity M2 to the light intensity control unit 31.

[0059] The light amount control unit 31 controls the light amount of the light source 32 based on the luminance evaluation value Lw and the luminance evaluation value Ls input from the luminance evaluation unit 24. At this time, the light amount control unit 31 controls the light amount of the light source 32 so as not to exceed the upper limit light amount M2 input from the multiplier 28.

[0060] According to the endoscope light intensity control device of this embodiment, the upper limit of the light intensity can be controlled based on information about the distance to the subject, so that the light intensity can be controlled appropriately regardless of the observation site.

[0061] The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications, combinations, and applications are possible within the scope of the invention without departing from the spirit of the invention.

Claims

1. An endoscope light intensity control device that controls a light intensity value based on an image acquired by an endoscope, comprising: a brightness evaluation unit that calculates an overall brightness evaluation value of the image and a brightness evaluation value of a periphery of the image; and a light intensity control unit that controls the light intensity value based on the larger brightness evaluation value of the overall brightness evaluation value and the periphery brightness evaluation value.

2. The endoscope light intensity control device described in claim 1, characterized in that the brightness evaluation unit divides the periphery of the image into multiple regions and calculates a brightness evaluation value for each of the multiple regions, and the light intensity control unit controls the light intensity value based on the largest brightness evaluation value among the brightness evaluation values ​​of the multiple regions and the overall brightness evaluation value.

3. An endoscope light intensity control device as described in claim 2, characterized in that the brightness evaluation unit calculates a contrast ratio in two areas among the multiple areas that are close to the brightest area, and multiplies the brightness evaluation value of the brightest area by a correction value corresponding to the contrast ratio.

4. An endoscope light intensity control device as described in claim 1, characterized in that it has: a light intensity upper limit value calculation unit that calculates a first upper limit value for light intensity control from distance information to the subject; a reduction coefficient calculation unit that calculates a reduction coefficient based on the overall brightness evaluation value of the image and the brightness evaluation value of the periphery of the image; and a multiplier that multiplies the first upper limit value by the reduction coefficient to calculate a second upper limit value for light intensity control, wherein the light intensity control unit controls the light intensity value so as not to exceed the second upper limit value when controlling the light intensity value based on the overall brightness evaluation value and the brightness evaluation value of the periphery.

5. An endoscopic light intensity control method for controlling a light intensity value based on an image acquired by an endoscope, comprising: calculating an overall luminance evaluation value of the image and a luminance evaluation value of a periphery of the image; and controlling the light intensity value based on the larger luminance evaluation value of the overall luminance evaluation value and the luminance evaluation value of the periphery.

6. An endoscopic light intensity control method according to claim 5, characterized in that the periphery of the image is divided into a plurality of regions, a brightness evaluation value is calculated for each of the plurality of regions, and the light intensity value is controlled based on the largest brightness evaluation value among the brightness evaluation values ​​of the plurality of regions and the overall brightness evaluation value.

7. An endoscopic light intensity control method as described in claim 6, characterized in that a contrast ratio is calculated for two areas among the plurality of areas that are adjacent to the brightest area, and a correction value corresponding to the contrast ratio is multiplied by the brightness evaluation value of the brightest area.

8. An endoscopic light intensity control method as described in claim 5, characterized in that it calculates a first upper limit value for light intensity control from information on the distance to the subject, calculates a reduction coefficient based on the overall brightness evaluation value of the image and the brightness evaluation value of the periphery of the image, multiplies the first upper limit value by the reduction coefficient to calculate a second upper limit value for light intensity control, and when controlling the light intensity value based on the overall brightness evaluation value and the brightness evaluation value of the periphery, controls the light intensity value so that it does not exceed the second upper limit value.

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