Local multiscale tone-mapping operator
First Claim
1. A method comprising:
- converting luminance values in an input high dynamic range (HDR) image into a logarithmic domain;
applying a global ratio operator to the luminance values in the logarithmic domain derived from the input high dynamic range (HDR) image to generate a high resolution gray scale ratio image in the logarithmic domain comprising luminance ratio values;
generating, based at least in part on the high resolution gray scale ratio image in the logarithmic domain, at least two different gray scale ratio images, merging the at least two different gray scale ratio images to generate a local multiscale gray scale ratio image that comprises a weighted combination of the at least two different gray scale ratio images, each being of a different spatial resolution level;
wherein the local multiscale gray scale ratio image is obtained using recursive processing;
using ratio values in the local multiscale gray scale ratio image with the luminance values in the logarithmic domain derived from the input HDR image to generate a tone-mapped gray scale image;
wherein the tone-mapped gray scale image comprises a fixed-point grayscale image with the same spatial dimensions as the spatial dimensions of the input HDR image; and
computing a reference maximum over the tone-mapped gray scale image such that a percentage of pixels that lie outside a color gamut are not more than a threshold.
1 Assignment
0 Petitions
Accused Products
Abstract
In a method to generate a tone-mapped image from a high-dynamic range image (HDR), an input HDR image is converted into a logarithmic domain and a global tone-mapping operator generates a high-resolution gray scale ratio image from the input HDR image. Based at least in part on the high-resolution gray scale ratio image, at least two different gray scale ratio images are generated and are merged together to generate a local multiscale gray scale ratio image that represents a weighted combination of the at least two different gray scale ratio images, each being of a different spatial resolution level. An output tone-mapped image is generated based on the high-resolution gray scale image and the local multiscale gray scale ratio image.
-
Citations
23 Claims
-
1. A method comprising:
-
converting luminance values in an input high dynamic range (HDR) image into a logarithmic domain; applying a global ratio operator to the luminance values in the logarithmic domain derived from the input high dynamic range (HDR) image to generate a high resolution gray scale ratio image in the logarithmic domain comprising luminance ratio values; generating, based at least in part on the high resolution gray scale ratio image in the logarithmic domain, at least two different gray scale ratio images, merging the at least two different gray scale ratio images to generate a local multiscale gray scale ratio image that comprises a weighted combination of the at least two different gray scale ratio images, each being of a different spatial resolution level; wherein the local multiscale gray scale ratio image is obtained using recursive processing; using ratio values in the local multiscale gray scale ratio image with the luminance values in the logarithmic domain derived from the input HDR image to generate a tone-mapped gray scale image; wherein the tone-mapped gray scale image comprises a fixed-point grayscale image with the same spatial dimensions as the spatial dimensions of the input HDR image; and computing a reference maximum over the tone-mapped gray scale image such that a percentage of pixels that lie outside a color gamut are not more than a threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. A method comprising:
-
applying a global tone mapping operator to luminance values derived from a high dynamic range (HDR) image to generate a high resolution gray scale ratio image comprising luminance ratio values; determining a number of spatial resolution levels in between a highest resolution level and a lowest resolution level; for each determined spatial resolution level from the highest resolution level to a spatial resolution level immediately above the lowest resolution level, downsampling a ratio image corresponding to the determined spatial resolution level to generate a succeeding ratio image corresponding to a spatial resolution level immediately lower than the determined spatial resolution level; for each determined spatial resolution level from the lowest resolution level to a spatial resolution level immediately below the highest resolution level, upsampling a ratio image corresponding to the determined spatial resolution level to generate an upsample ratio image corresponding to the each spatial resolution level; determining a weight factor value for each different ratio image of a number of ratio images each corresponding to a spatial resolution level of the number of determined spatial resolution levels, thereby giving rise to a number of weight factors; determining a local multiscale ratio image as a weighted combination of the number of ratio images as weighted by the number of weight factors. - View Dependent Claims (22, 23)
-
Specification