Patent ID: 7929753

Claim:
A circuitry-implemented method for image processing, the method comprising: (1) obtaining digital data for one or more image portions p 1 , p 2 , . . . , wherein for each image portion p (p=p 1 , p 2 , . . . ), the digital data represent at least one coordinate S 1 of a color S(p) of the portion p in a first coordinate system, wherein for a color S having tristimulus values T 1 , T 2 , T 3 in a second coordinate system: (1A) the coordinate S 1 is defined by a B value B =√{square root over ( g 11 T 1 2 +g 22 T 2 2 +g 33 T 3 2 +g 12 T 1 T 2 +g 13 T 1 T 3 +g 23 T 2 T 3 )} wherein g 11 , g 22 , g 33 , g 12 , g 13 , g 23 are predefined constants, and g 11 , g 22 , g 33 are not equal to zero, or (1B) the coordinate S 1 is defined by the B value and by a sign of a predefined function of one or more of T 1 , T 2 , T 3 ; (2) processing the digital data to determine one or more V-values each of which represents a color property of the corresponding image portion, the processing comprising, for at least one B value, determining the corresponding V value as V=k 1 +k 2 *log b (k 3 B+k 4 ), wherein k 1 , k 2 , k 3 , k 4 , b are predefined constants, k 2 and k 3 are not zero, and b is positive and not equal to one.