Entropy deficiency based image

Abstract

A method for obtaining a quantization factor for image compression by quantization of coefficients of a transformation of an image or part thereof, comprising determining an entropy-related sensitivity to quantization of at least a part of the image; and determining a quantization factor based on the entropy-related sensitivity.

1 . A method for obtaining a quantization factor for image compression by quantization of coefficients of a transformation of the image or part thereof, comprising:
 (a) determining an entropy-related sensitivity to quantization of at least a part of the image; and   (b) determining a quantization factor based on the entropy-related sensitivity.   
   
   
       2 . A method according to  claim 1 , wherein determining a sensitivity to quantization comprises determining a change in entropy of a quantized at least a part of the image relative to the entropy of the at least part of the image, or a derivation thereof. 
   
   
       3 . A method according to  claim 2 , wherein the derivation comprises the ratio between the entropy of a quantized at least a part of an image and the entropy of the at least part of the image (ED). 
   
   
       4 . A method according to  claim 3 , comprising determining a threshold of ED above which the visual quality of a compressed at least a part of an image is insensitive, at least approximately, to ED. 
   
   
       5 . A method according to  claim 4 , wherein the threshold is independent of the image. 
   
   
       6 . A method according to  claim 1 , comprising determining a threshold of a complexity quantification of the at least a part of an image above which the visual quality of a compressed at least a part of an image is insensitive, at least approximately, to the complexity quantification. 
   
   
       7 . A method according to  claim 6 , wherein the threshold is independent of the image. 
   
   
       8 . A method according to  claim 1 , wherein determining a quantization factor based on the entropy-related sensitivity comprises a linear function of the entropy-related sensitivity. 
   
   
       9 . A method according to  claim 1 , wherein determining a quantization factor comprises determination according to a range of quantization factors. 
   
   
       10 . A method according to  claim 9 , wherein determination according to a range of quantization factors comprises a linear function of the rounded range of quantization factors. 
   
   
       11 . A method according to  claim 10 , wherein the quantization factor is adjusted according to on at least one of the image target bit-rate, the image target compression ratio, the target visual quality of the compressed image, or a combination thereof. 
   
   
       12 . A method according to  claim 9 , wherein the range of quantization factors is based on at least one of the image target bit-rate, the image target compression ratio, the target visual quality of the compressed image, or a combination thereof. 
   
   
       13 . A method according to  claim 1 , wherein the at least part of an image comprises is arbitrary. 
   
   
       14 . A method according to  claim 1 , wherein the at least part of the image comprises a difference between a decompression of a previously compressed part of the image and the original part of the image. 
   
   
       15 . A method for evaluation of entropy-related sensitivity to quantization of an image or part thereof to obtain a quantization factor for image compression by quantization of coefficients of a transformation of the image or part thereof, comprising:
 (a) determining a function of entropy-related quantification with respect to a complexity quantification of at least a part of the image; and   (b) determining a quantization factor based on the function.   
   
   
       16 . A method according to  claim 15 , wherein the entropy-related quantification comprises, at least approximately, a ratio between the entropy of a quantized at least a part of an image and the entropy of the at least part of the image (ED). 
   
   
       17 . A method according to  claim 15 , wherein a quantification of the complexity comprises a standard deviation of the at least part of the image. 
   
   
       18 . A method according to  claim 15 , wherein the function comprises an exponential function of the complexity quantification. 
   
   
       19 . A method according to  claim 18 , wherein the function is, at least approximately, independent of the image. 
   
   
       20 . A method according to  claim 18 , wherein the function comprises an approximation of an exponential function. 
   
   
       21 . A method according to  claim 15 , wherein determining a quantization factor comprises determination according to a range of quantization factors. 
   
   
       22 . A method according to  claim 21 , wherein the range of quantization factors is based on at least one of the image target bit-rate, the image target compression ratio, the target visual quality of the compressed image, or a combination thereof. 
   
   
       23 . A method according to  claim 16 , comprising determining, according to at least one of the curvature or the slope of the function, a threshold of ED above which the visual quality of a compressed at least a part of an image is insensitive, at least approximately, to ED. 
   
   
       24 . A method according to  claim 15 , comprising determining, according to at least one of the curvature or the slope of the function, a threshold of a complexity quantification of the at least a part of an image above which the visual quality of a compressed at least a part of an image is insensitive, at least approximately, to the complexity quantification. 
   
   
       25 . Apparatus configured to carry out the method of  claim 1 .