Patent ID: 8179981

Claim:
A method for determining in picture signal encoding, which includes transform and quantization of transform coefficient blocks, a bit allocation for groups of pixel blocks in a picture, whereby said picture is divided into a regular grid of pixel blocks and said groups of pixel blocks belong to different attention importance levels of corresponding arbitrary-shaped areas of pixel blocks in said picture, and wherein an encoding/decoding distortion of each group of pixel blocks is to be controlled such that it is basically proportional to the attention importance level for that group of pixel blocks, and wherein a bit budget is given for an encoded picture and said quantization is controlled by a quantization parameter, the method comprising: for a current picture, with respect to candidates of said quantization parameter, establishing for each group of pixel blocks, tables or lists or functions for an estimated distortion and for a bit rate and for a number of zero-amplitude coefficients following said quantization; calculating for the pixel blocks of each group of said groups of pixel blocks a corresponding distortion distribution, using said tables or lists or functions for the estimated distortion and for the bit rate and, using also the output from the following, modifying said distortion distribution in order to reach said bit budget; wherein the calculating for each group of pixel blocks the corresponding distortion distribution further comprises: without regarding different distortion levels in different attention level areas, calculating a corresponding initial distortion value D i for each group of pixel blocks; calculating a distortion unit D u = ⅇ ( ∑ i = 1 N ⁢ l ⁢ ⁢ n ⁢ D _ _ i - ∑ i = 1 N ⁢ l ⁢ ⁢ n ⁢ ⁢ M i - ∑ i = 1 N ⁢ l ⁢ ⁢ nK i ) / N , wherein M i is the attention importance level for a corresponding group of pixel blocks and K i is the number of pixel blocks in the corresponding group of pixel blocks and N is the number of attention levels; calculating from said D u value a refined distortion distribution by D i =D u ×M i for each group of pixel blocks, whereby said modifying of said distortion distribution D i is performed here; based on said tables or lists or functions for the estimated distortion and for the bit rate, and based on said calculated distortion distribution, calculating an estimated bit rate for each group of pixel blocks; performing a rho-domain bit allocation for each group of pixel blocks using said estimated bit rate and said table or list or function for the number of zero-amplitude coefficients following said quantization, to determine a corresponding one of said quantization parameters for quantizing and encoding the pixel blocks.