The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 06, 1995
Filed:
Apr. 09, 1993
Daniel Devimeux, Perros-Guirec, FR;
Jean-Claude Jolivet, St-Michael En Greve, FR;
SAT (Societe Anonyme de Telecommunications), Paris, FR;
Abstract
Coding and decoding of digital images by transformation of pixel blocks reduce the data bit rate. Transformation of blocks leads to discontinuities in brightness level for pixels bordering on block boundaries. These discontinuities are detected for each given bordering pixel by a change of sign of two level gradients respectively computed with the levels of two pixels adjacent to the bordering pixel. A brightness level of the bordering pixel is then corrected by a discontinuity correction factor evaluated from a discontinuity divergence equal to the absolute value of the difference between the brightness level of the bordering pixel and an arithmetical average of brightness levels of the two adjacent pixels, as a function of a quantization pitch associated with a block to which belongs the bordering pixel. The block is then corrected in its entirety to attenuate the differences of average brightness levels between two adjacent blocks generated by the coding and decoding.