Systems and methods for generating enhanced opthalmic images

Patent metadata

Field	Value
Publication number	US-12482082-B2
Application number	US-202217880427-A
Country	US
Kind code	B2
Filing date	Aug 3, 2022
Priority date	Aug 19, 2021
Publication date	Nov 25, 2025
Grant date	Nov 25, 2025

Abstract

Certain aspects of the present disclosure provide an ophthalmic imaging device for enhancing images. The device comprises an image capture component configured to generate an image stream comprising a first frame preceding a second frame, both capturing a branch of veins in an eye. The device further comprises an image processor configured to calculate first order statistics for a plurality of blocks for the first frame and to interpolate first order statistics for the first frame based at least in part on the branch of veins. The image processor is also configured to generate a tone mapping function and calculate tone mapping values for individual pixels of the second frame based on the tone mapping function. The image processor is additionally configured to generate an enhanced frame based on the calculated tone mapping values for individual pixels of the second frame to the pixels of the second frame.

First claim

What is claimed is:

1 . An ophthalmic imaging device comprising:
an image capture component configured to generate an image stream comprising a first frame capturing a branch of veins in an eye of a patient and a second frame capturing the branch of veins, the second frame following the first frame in the image stream; and an image processor configured to:
calculate first order statistics for individual blocks of a plurality of blocks for the first frame, each block of the plurality of blocks for the first frame comprising a plurality of first frame pixels;
interpolate first order statistics for the first frame based on the calculated first order statistics for the individual blocks of the plurality of blocks for the first frame, wherein the first order statistics for the first frame are based, at least in part, on the branch of veins;
calculate first order statistics for each block of a plurality of blocks for a third frame capturing the branch of veins in the eye, each block of the plurality of blocks for the third frame comprising a plurality of third frame pixels;
interpolate first order statistics for the third frame based on the calculated first order statistics for each block of the plurality of blocks for the third frame, wherein the first order statistics for the third frame are based, at least in part, on the branch of veins;
generate first weighted statistics for the first frame based on application of a first weight to the interpolated first order statistics for the first frame;
generate second weighted statistics for the third frame based on application of a second weight to the interpolated first order statistics for the third frame, the second weight being less than the first weight;
generate a tone mapping function for pixels of the second frame based on the interpolated first order statistics for the first frame, the tone mapping function for the pixels of the second frame based on the first weighted statistics and the second weighted statistics;
calculate tone mapping values for individual pixels of the second frame based on the tone mapping function; and
generate an enhanced frame based on application of the calculated tone mapping values for individual pixels of the second frame to the pixels of the second frame.

2 . The ophthalmic imaging device of claim 1 , wherein the image processor is further configured to: identify a static object based on detection of the static object at a first location in the first frame and detection of the static object at a corresponding location in the third frame.

3 . The ophthalmic imaging device of claim 1 , wherein the image processor is further configured to identify a non-static object based on detection of the non-static object in only one of the first frame and the third frame or based on detection of the non-static object at a first location in the first frame and a second location different from the first location in the third frame.

4 . The ophthalmic imaging device of claim 1 , wherein the first order statistics for the first frame comprise:
a mean pixel intensity for each block of the plurality of blocks for the first frame; and an intensity standard deviation for each block of the plurality of blocks for the first frame.

5 . The ophthalmic imaging device of claim 1 , wherein the image processor is further configured to divide the first frame into the plurality of blocks.

6 . The ophthalmic imaging device of claim 1 , wherein each block of the plurality of blocks has a same size and shape and is evenly spaced through the first frame relative to other blocks of the plurality of blocks.

7 . The ophthalmic imaging device of claim 6 , wherein the image processor is further configured to:
identify a portion of the first frame that comprises space void of relevant aspects of the eye; and prevent any blocks of the plurality of blocks from being placed in the portion that comprises a white space.

8 . The ophthalmic imaging device of claim 1 , wherein:
the first order statistics correspond to a luminance channel of the first frame, and the tone mapping function and the tone mapping values apply to a luminance channel of the second frame.

9 . The ophthalmic imaging device of claim 1 , wherein:
the first order statistics correspond to a grayscale channel obtained from green pixels of the first frame, and the tone mapping function and the tone mapping values apply to a grayscale channel from green pixels of the second frame.

10 . The ophthalmic imaging device of claim 1 , wherein the image capture component comprises a high dynamic range (HDR) camera.

11 . The ophthalmic imaging device of claim 1 , wherein:
the tone mapping function is limited based on a contrast limit determined based on the first frame, and the contrast limit comprises a maximum contrast value and a minimum contrast value.

12 . A ophthalmic image processing method, comprising:
generating an image stream comprising a first frame capturing a branch of veins in an eye of a patient and a second frame capturing the branch of veins in the eye, the second frame following the first frame in the image stream; calculating first order statistics for individual blocks of a plurality of blocks for the first frame, the individual blocks of the plurality of blocks for the first frame comprising a plurality of first frame pixels; interpolating first order statistics for the first frame based on the calculated first order statistics for the individual blocks of the plurality of blocks for the first frame, wherein the first order statistics for the first frame are based, at least in part, on the branch of veins; calculating first order statistics for each block of a plurality of blocks for a third frame capturing the branch of veins in the eye, each block of the plurality of blocks for the third frame comprising a plurality of third frame pixels; interpolating first order statistics for the third frame based on the calculated first order statistics for each block of the plurality of blocks for the third frame, wherein the first order statistics for the third frame are based, at least in part, on the branch of veins; generating first weighted statistics for the first frame based on application of a first weight to the interpolated first order statistics for the first frame; generating second weighted statistics for the third frame based on application of a second weight to the interpolated first order statistics for the third frame, the second weight being less than the first weight; generating a tone mapping function for pixels of the second frame based on the interpolated first order statistics for the first frame, the tone mapping function for the pixels of the second frame based on the first weighted statistics and the second weighted statistics; calculating tone mapping values for individual pixels of the second frame based on the tone mapping function; and generating an enhanced frame based on application of the calculated tone mapping values for individual pixels of the second frame to the pixels of the second frame.

13 . The ophthalmic image processing method of claim 12 , further comprising:
identifying a static object based on detection of the static object at a first location in the first frame and detection of the static object at a corresponding location in the third frame, and identifying a non-static object based on detection of the non-static object in only one of the first frame and the third frame or based on detection of the non-static object at a first location in the first frame and a second location different from the first location in the third frame.

Assignees

• Alcon Inc

Inventors

• Yin Lu
• Sarangapani Ramesh

Classifications

• G06T2207/30041

  Eye; Retina; Ophthalmic · CPC title

• G06T2207/20212

  Image combination · CPC title

• G06T2207/20208

  High dynamic range [HDR] image processing · CPC title

• G06T2207/20021

  Dividing image into blocks, subimages or windows · CPC title

• G06T2207/10024

  Color image · CPC title