Endoscope system with scanning function
An endoscope system has a light source system configured to emit illumination light on a target area, a scanner configured to periodically scan the illumination light over a target area at predetermined time intervals, and an imager configured to receive the illumination light reflected from the target area and to acquire in succession a sequence of image-pixel signals. Further, the endoscope system has a luminance detector that detects in succession a sequence of luminance data of the object image from the sequence of image-pixel signals; and a brightness adjuster that adjusts the brightness of an observed image on the basis of the sequence of luminance data. Then, the brightness adjuster adjusts an amount of illumination light in accordance with a scanning position of the illumination light.
1. An endoscope system comprising:
a light source system configured to emit illumination light on a target area;
a scanner configured to periodically scan the illumination light over a target area, said scanner comprising a fiber driver that vibrates a tip portion of a scanning fiber in two dimensions to scan the illumination light, vibration of the tip portion of the scanning fiber determining a scan path of the illumination light, the scan path in each frame occurs over a time interval defining a frame of an object image;
an imager configured to receive the illumination light reflected from the target area and to acquire a sequence of image-pixel signals in succession;
a luminance detector that detects, in succession, a sequence of luminance data of the object image from the sequence of image-pixel signals; and
a brightness adjuster that adjusts the brightness of an observed image on the basis of the sequence of luminance data, said brightness adjuster adjusting an amount of illumination light in accordance with a scanning position of the illumination light on the scan path, such that the amount of illumination light in the frame which occurs over the time interval is time-sequentially changed,
wherein the brightness adjuster determines the amount of illumination light in a current frame by correcting the amount of illumination light in a previous frame.
2. The endoscope system of claim 1 , wherein said brightness adjuster increases the amount of illumination light incident on a scanning position corresponding to a pixel having a luminance level less than 50% of a maximum luminance level, and decreases the amount of illumination light incident on a scanning position corresponding to a pixel having a luminance level greater than 50% of the maximum luminance level.
3. The endoscope system of claim 1 , wherein said brightness adjuster adjusts the amount of illumination light so as to narrow the range of luminance level variance.
4. The endoscope system of claim 1 , wherein said brightness adjuster increases the illumination light by a larger amount as a detected luminance level of a scanning position decreases when the detected luminance level of the scanning position is less than 50% of a maximum luminance level, and decreases the amount of illumination light by a larger amount as a detected luminance level of a scanning position increases when the detected luminance level of the scanning position is greater than 50% of a maximum luminance level.
5. The endoscope system of claim 1 , wherein said brightness adjuster increases or decreases the amount of illumination light incident on each scanning position in accordance with a difference between a detected luminance level of a scanning position and a predetermined target luminance level.
6. The endoscope system of claim 1 , wherein said brightness adjuster suspends adjustment of the amount of illumination light in a subsequent scanning interval when a percentage of luminance data that fall outside of an upper or lower limit tolerance level is more than a threshold value.
7. The endoscope system of claim 1 , wherein said brightness adjuster adjusts the amount of illumination light incident on a scanning position corresponding to an edge portion of an observed image.
8. The endoscope system of claim 1 , wherein said light source system comprises:
a light source that emits R, G, and B light as illumination light; and
a light source driver that controls the intensity of illumination light.
9. An apparatus for adjusting the brightness of an observed image according to an endoscope system, comprising:
a luminance detector that detects, in succession, a sequence of luminance data of the object image on the basis of a sequence of image-pixel signals that are acquired in succession by illumination light reflected from the target area, while a scanner periodically scans the illumination light over the target area by vibrating a tip portion of a scanning fiber in two dimensions, vibration of the tip portion of the scanning fiber determining a scan path of the illumination light, the scan path in each frame occurs over a time interval defining a frame of an object image;
a determiner that determines whether or not a brightness adjustment is necessary, on the basis of the sequence of luminance data; and
a brightness adjuster that adjusts the brightness of an observed image on the basis of the sequence of luminance data when the brightness adjustment is necessary, said brightness adjuster adjusting an amount of illumination light in accordance with a scanning position of the illumination light on the scan path, such that the amount of illumination light in the frame which occurs over the time interval is time-sequentially changed,
wherein the brightness adjuster determines the amount of illumination light in a current frame by correcting the amount of illumination light in a previous frame.
10. A non-transitory computer readable medium that stores a program executable by a computer, for adjusting the brightness of an observed image according to an endoscope system, the program comprising:
a luminance detection code segment that detects, in succession, a sequence of luminance data of the object image on the basis of a sequence of image-pixel signals that are acquired in succession by illumination light reflected from the target area, while a scanner periodically scans the illumination light over the target area by vibrating a tip portion of a scanning fiber in two dimensions, vibration of the tip portion of the scanning fiber determining a scan path of the illumination light, the scan path in each frame occurs over a time interval defining a frame of an object image;
a determination code segment that determines whether or not a brightness adjustment is necessary, on the basis of the sequence of luminance data; and
a brightness adjustment code segment that adjusts the brightness of an observed image on the basis of the sequence of luminance data when the brightness adjustment is necessary, the brightness adjustment code segment adjusting an amount of illumination light in accordance with a scanning position of the illumination light on the scan path, such that the amount of illumination light in the frame which occurs over the time interval is time-sequentially changed,
wherein the brightness adjustment code segment determines the amount of illumination light in a current frame by correcting the amount of illumination light in a previous frame.
11. A method for adjusting the brightness of an observed image according to an endoscope system, comprising:
detecting, in succession, a sequence of luminance data of the object image on the basis of a sequence of image-pixel signals that are acquired in succession by illumination light reflected from the target area, while a scanner periodically scans the illumination light over the target area by vibrating a tip portion of a scanning fiber in two dimensions, vibration of the tip portion of the scanning fiber determining a scan path of the illumination light, the scan path in each frame occurs over a time interval defining a frame of an object image;
determining whether or not a brightness adjustment is necessary, on the basis of the sequence of luminance data; and
adjusting the brightness of an observed image on the basis of the sequence of luminance data when the brightness adjustment is necessary, the adjusting comprising adjusting an amount of illumination light in accordance with a scanning position of the illumination light on the scan path, such that the amount of illumination light in the frame which occurs over the time interval is time-sequentially changed,
wherein the adjusting determines the amount of illumination light in a current frame by correcting the amount of illumination light in a previous frame.
12. The endoscope system according to claim 1 , wherein the fiber driver vibrates the tip portion of the scanning fiber such that the illumination light is scanned spirally.
13. The apparatus according to claim 9 , wherein the tip portion of the scanning fiber vibrates such that the illumination light is scanned spirally.
14. The non-transitory computer readable medium according to claim 10 , wherein the tip portion of the scanning fiber vibrates such that the illumination light is scanned spirally.
15. The method according to claim 11 , wherein the tip portion of the scanning fiber vibrates such that the illumination light is scanned spirally.
16. The endoscope system according to claim 1 , wherein the scanner is provided in a tip portion of the endoscope, and the fiber driver vibrates the tip portion of the scanning fiber such that the scanning position of the illumination light changes, while the position of the tip portion of the endoscope does not change.
17. The endoscope system according to claim 1 , wherein the brightness adjuster determines the amount of illumination light of a scanning position on the scan path in the current frame by correcting the amount of illumination light on a corresponding scanning position on the scan path in the previous frame.