Endoscopic image enhancement using contrast limited adaptive histogram equalization (CLAHE) implemented in a processor
First Claim
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1. An endoscope system comprising:
- an endoscope including a first viewing element and a second viewing element;
a control unit operatively coupled to the endoscope by a cable, wherein the control unit comprises;
a base board module;
one or more processing boards that implement a contrast limited adaptive histogram equalization (CLAHE) algorithm to enhance images obtained by the first viewing element and the second viewing element, wherein the one or more processing boards perform the steps of;
receiving a first YCbCr color space video stream from the first viewing element and a second YCbCr color space video stream from the second viewing element,converting the first YCbCr color space video stream to a first Lab color space video stream and the second YCbCr color space video stream to a second Lab color space video stream,building and storing first histogram information based on the first Lab color space video stream,building and storing second histogram information based on the second Lab color space video stream,converting the first histogram information into first cumulative distribution function values including applying a first clipping threshold to the first histogram information,converting the second histogram information into second cumulative distribution function values including applying a second clipping threshold to the second histogram information, wherein the second clipping threshold is different from the first clipping threshold,obtaining a first plurality of Lab color space frames from the first Lab color space video stream and a second plurality of Lab color space frames from the second Lab color space video stream,rearranging the first plurality of Lab color space frames to generate a plurality of first delayed Lab streams,rearranging the second plurality of Lab color space frames to generate a plurality of second delayed Lab streams,generating a first enhanced Lab stream based on the plurality of first delayed Lab streams and the first cumulative distribution function values,generating a second enhanced Lab stream based on the plurality of second delayed Lab streams and the second cumulative distribution function values, andsending output video streams indicative of the first enhanced Lab stream and the second enhanced Lab stream to a display.
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Abstract
Systems and methods of enhancing images use a contrast limited adaptive histogram equalization (CLAHE) algorithm in a field programmable gate array (FPGA). The images may be obtained by the imaging elements of a multiple imaging elements endoscope of an endoscopy system.
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Citations
19 Claims
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1. An endoscope system comprising:
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an endoscope including a first viewing element and a second viewing element; a control unit operatively coupled to the endoscope by a cable, wherein the control unit comprises; a base board module; one or more processing boards that implement a contrast limited adaptive histogram equalization (CLAHE) algorithm to enhance images obtained by the first viewing element and the second viewing element, wherein the one or more processing boards perform the steps of; receiving a first YCbCr color space video stream from the first viewing element and a second YCbCr color space video stream from the second viewing element, converting the first YCbCr color space video stream to a first Lab color space video stream and the second YCbCr color space video stream to a second Lab color space video stream, building and storing first histogram information based on the first Lab color space video stream, building and storing second histogram information based on the second Lab color space video stream, converting the first histogram information into first cumulative distribution function values including applying a first clipping threshold to the first histogram information, converting the second histogram information into second cumulative distribution function values including applying a second clipping threshold to the second histogram information, wherein the second clipping threshold is different from the first clipping threshold, obtaining a first plurality of Lab color space frames from the first Lab color space video stream and a second plurality of Lab color space frames from the second Lab color space video stream, rearranging the first plurality of Lab color space frames to generate a plurality of first delayed Lab streams, rearranging the second plurality of Lab color space frames to generate a plurality of second delayed Lab streams, generating a first enhanced Lab stream based on the plurality of first delayed Lab streams and the first cumulative distribution function values, generating a second enhanced Lab stream based on the plurality of second delayed Lab streams and the second cumulative distribution function values, and sending output video streams indicative of the first enhanced Lab stream and the second enhanced Lab stream to a display. - View Dependent Claims (2, 3, 4, 5, 6, 18)
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7. A method of enhancing images obtained by a plurality of viewing elements in an endoscope system using a contrast limited adaptive histogram equalization (CLAHE) process, wherein said endoscope system comprises (a) a control unit having a baseboard module including one or more processing boards configured to implement said process, and (b) an endoscope operatively coupled to the control unit by a cable, the endoscope including the plurality of viewing elements, said method comprising the steps of:
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receiving a plurality of YCbCr color space video streams from each of the plurality of viewing elements; converting the plurality of YCbCr color space video streams to Lab color space video streams; building and storing histogram information based on the plurality of Lab color space video streams including splitting the plurality of Lab color space video streams into a plurality of tiles, wherein units of the tile heights are in video lines and units of the tile widths are in pixels, wherein each of the plurality of tiles overlaps with its neighboring tiles; converting the histogram information into cumulative distribution function values; obtaining said Lab color space video streams as Lab color space frames; rearranging Lab color space frame data to generate delayed Lab streams; generating a plurality of enhanced Lab streams, using the plurality of delayed Lab streams and the cumulative distribution function values; and displaying output video streams indicative of the plurality of enhanced Lab streams. - View Dependent Claims (8, 9, 10)
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11. A non-transient computer readable medium containing program instructions for causing a computer to perform a method of enhancing images obtained by three viewing elements in an endoscope system using a contrast limited adaptive histogram equalization (CLAHE) process, wherein said endoscope system comprises (a) a control unit with a baseboard module including a processor configured to implement said process, and (b) an endoscope operatively coupled to the control unit by a cable, the endoscope including the three viewing elements, said method comprising the steps of:
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receiving three YCbCr color space video streams from the three viewing elements with an adapter on said processor, each of the three viewing elements providing one of said three YCbCr color space video streams; converting each of the three YCbCr color space video streams to corresponding three Lab color space video streams within said adapter; building and storing histogram information based on the three Lab color space video streams within a histogram module on said processor; converting the histogram information into cumulative distribution function values within the histogram module; transmitting the three Lab color space video streams to a frame grabber on said processor in a form of a video stream obtained from a single viewing element with a Y input of the frame grabber being fed by a Lab color space video stream of a first viewing element of the three viewing elements, a Cb input of the frame grabber being fed by a Lab color space video stream of a second viewing element of the three viewing elements, and a Cr input of the frame grabber being fed by a Lab color space video stream of a third viewing element of the three viewing elements; acquiring the three Lab color space video streams as corresponding Lab color space frames within said frame grabber; acquiring the Lab color space frames from the frame grabber using a fetching module on said processor; rearranging Lab color space frame data within said fetching module to generate three delayed Lab streams corresponding to the Lab color space frames acquired by the fetching module; generating three enhanced Lab streams, using the three delayed Lab streams and the cumulative distribution function values, within an interpolation algorithm module on said processor; and prompting a display of output video streams indicative of the three enhanced Lab streams on one or more displays in operative communication with the processor. - View Dependent Claims (12, 13, 14, 15, 16, 17, 19)
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Specification