Color correction system and method

Abstract

A method for color correction includes obtaining a noise evaluation image and a corrected noise evaluation image, determining a peak signal-to-noise ratio (PSNR) difference by comparing the noise evaluation image and the corrected noise evaluation image, obtaining a downsampled noise evaluation image and a downsampled corrected noise evaluation image, determining a downsampled PSNR difference by comparing the downsampled noise evaluation image and the downsampled corrected noise evaluation image, and determining a noise amplification metric based on a weighted average of the PSNR difference and the downsampled PSNR difference.

What is claimed is: 
     
         1 . A method for color correction, comprising:
 obtaining a noise evaluation image and a corrected noise evaluation image;   determining a peak signal-to-noise ratio (PSNR) difference by comparing the noise evaluation image and the corrected noise evaluation image;   obtaining a downsampled noise evaluation image and a downsampled corrected noise evaluation image;   determining a downsampled PSNR difference by comparing the downsampled noise evaluation image and the downsampled corrected noise evaluation image; and   determining a noise amplification metric based on a weighted average of the PSNR difference and the downsampled PSNR difference.   
     
     
         2 . The method of  claim 1 , wherein the corrected noise evaluation image is obtained by applying a color correction operation to the noise evaluation image, wherein the color correction operation is associated with a plurality of color correction parameters. 
     
     
         3 . The method of  claim 2 , further comprising:
 adjusting the plurality of color correction parameters based on the noise amplification metric.   
     
     
         4 . The method of  claim 2 , wherein the plurality of color correction parameters form a color correction matrix or a look-up table, and wherein the color correction operation includes performing a matrix multiplication using the color correction matrix or performing a look-up operation and an interpolation operation using the look-up table. 
     
     
         5 . The method of  claim 2 , further comprising:
 adjusting the plurality of color correction parameters based on a color correction error, wherein the color correction error is determined by:
 obtaining input color values and reference color values for respective color references; 
 obtaining corrected input color values by applying the color correction operation to the input color values; and 
 comparing the corrected input color values with the reference color values. 
   
     
     
         6 . The method of  claim 1 , wherein the noise evaluation image comprises a plurality of color patches and the corrected evaluation image comprises a plurality of corrected color patches, and wherein the downsampled noise evaluation image comprises a plurality of downsampled color patches and the downsampled corrected evaluation image comprises a plurality of downsampled corrected color patches. 
     
     
         7 . The method of  claim 6 , wherein determining the PSNR difference comprises determining the PSNR difference by:
 computing a PSNR for each color patch of the noise evaluation image;   computing a corrected PSNR for each corrected color patch of the corrected noise evaluation image; and   computing a weighted average of a difference between the PSNR and the corrected PSNR for each pair of the color patch and the corrected color patch.   
     
     
         8 . The method of  claim 6 , wherein determining the downsampled PSNR difference comprises determining the downsampled PSNR difference by:
 computing a downsampled PSNR for each downsampled color patch of the downsampled noise evaluation image;   computing a downsampled corrected PSNR for each downsampled corrected color patch of the downsampled corrected noise evaluation image; and   computing a weighted average of a difference between the downsampled PSNR and the downsampled corrected PSNR for each pair of the downsampled color patch and the downsampled corrected color patch.   
     
     
         9 . An imaging system comprising:
 a processor, configured to:
 obtain a noise evaluation image and a corrected noise evaluation image; 
 determine a peak signal-to-noise ratio (PSNR) difference by comparing the noise evaluation image and the corrected noise evaluation image; 
 obtain a downsampled noise evaluation image and a downsampled corrected noise evaluation image; 
 determine a downsampled PSNR difference by comparing the downsampled noise evaluation image and the downsampled corrected noise evaluation image; and 
 determine a noise amplification metric based on a weighted average of the PSNR difference and the downsampled PSNR difference. 
   
     
     
         10 . The imaging system of  claim 9 , further comprising:
 a memory, configured to store a plurality of color correction parameters associated with a color correction operation;   wherein the processor is further configured to:
 apply the color correction operation to the noise evaluation image to obtain the corrected noise evaluation image; and 
 adjust the plurality of color correction parameters based on the noise amplification metric. 
   
     
     
         11 . The imaging system of  claim 10 , wherein the processor is further configured to:
 generate a color correction matrix or a look-up table using the plurality of color correction parameters; and   perform a matrix multiplication using the color correction matrix or perform a look-up operation and an interpolation operation using the look-up table.   
     
     
         12 . The imaging system of  claim 9 , wherein the noise evaluation image comprises a plurality of color patches and the corrected evaluation image comprises a plurality of corrected color patches, and wherein the downsampled noise evaluation image comprises a plurality of downsampled color patches and the downsampled corrected evaluation image comprises a plurality of downsampled corrected color patches. 
     
     
         13 . The imaging system of  claim 12 , wherein the processor is further configured to:
 compute a PSNR for each color patch of the noise evaluation image;   compute a corrected PSNR for each corrected color patch of the corrected noise evaluation image; and   determine the PSNR difference by computing a weighted average of a difference between the PSNR and the corrected PSNR for each pair of the color patch and the corrected color patch.   
     
     
         14 . The imaging system of  claim 12 , wherein the processor is further configured to:
 compute a downsampled PSNR for each downsampled color patch of the downsampled noise evaluation image;   compute a downsampled corrected PSNR for each downsampled corrected color patch of the downsampled corrected noise evaluation image; and   determine the downsampled PSNR difference by computing a weighted average of a difference between the downsampled PSNR and the downsampled corrected PSNR for each pair of the downsampled color patch and the downsampled corrected color patch.   
     
     
         15 . A non-transitory readable medium with instructions stored thereon that, when executed by a processor, perform the steps comprising:
 obtaining a noise evaluation image and a corrected noise evaluation image;   determining a peak signal-to-noise ratio (PSNR) difference by comparing the noise evaluation image and the corrected noise evaluation image;   obtaining a downsampled noise evaluation image and a downsampled corrected noise evaluation image;   determining a downsampled PSNR difference by comparing the downsampled noise evaluation image and the downsampled corrected noise evaluation image; and   determining a noise amplification metric based on a weighted average of the PSNR difference and the downsampled PSNR difference.   
     
     
         16 . The non-transitory readable medium of  claim 15 , wherein said steps further comprise:
 obtaining the corrected noise evaluation image by applying a color correction operation to the noise evaluation image, wherein the color correction operation is associated with a plurality of color correction parameters; and   adjusting the plurality of color correction parameters based on the noise amplification metric.   
     
     
         17 . The non-transitory readable medium of  claim 16 , wherein said steps further comprise:
 generating a color correction matrix or a look-up table using the plurality of color correction parameters; and   performing a matrix multiplication using the color correction matrix or performing a look-up operation and an interpolation operation using the look-up table.   
     
     
         18 . The non-transitory readable medium of  claim 15 , wherein the noise evaluation image comprises a plurality of color patches and the corrected evaluation image comprises a plurality of corrected color patches, and wherein the downsampled noise evaluation image comprises a plurality of downsampled color patches and the downsampled corrected evaluation image comprises a plurality of downsampled corrected color patches. 
     
     
         19 . The non-transitory readable medium of  claim 18 , wherein said steps further comprise:
 computing a PSNR for each color patch of the noise evaluation image;   computing a corrected PSNR for each corrected color patch of the corrected noise evaluation image; and   determining the PSNR difference by computing a weighted average of a difference between the PSNR and the corrected PSNR for each pair of the color patch and the corrected color patch.   
     
     
         20 . The non-transitory readable medium of  claim 18 , wherein said steps further comprise:
 computing a downsampled PSNR for each downsampled color patch of the downsampled noise evaluation image;   computing a downsampled corrected PSNR for each downsampled corrected color patch of the downsampled corrected noise evaluation image; and   determining the downsampled PSNR difference by computing a weighted average of a difference between the downsampled PSNR and the downsampled corrected PSNR for each pair of the downsampled color patch and the downsampled corrected color patch.