Patent ID: 8270710

Claim:
An apparatus-implemented method for image processing, the method comprising converting a digital image between a first digital representation of the image and a second digital representation of the image, wherein the image comprises a plurality of image portions, wherein at each said image portion the image has color coordinates T 1 , T 2 , T 3 in a predefined linear color coordinate system (CCS); wherein at least for each said image portion whose color coordinates T 1 , T 2 , T 3 are such that a value S 1 =√{square root over ( T 1 2 +T 2 2 +T 3 2 )} is in a predefined range, the first digital representation comprises color coordinates s 1 , s 2 , s 3 such that: s 1 =c 1 ·(ln( c 2 S 1 +c 3 )+ c 4 ) s 2 =c 5 ·T 2 /S 1 s 3 =c 6 ·T 3 /S 1 wherein c 1 , c 2 , c 3 , c 4 , c 5 , c 6 are predefined constants independent of the image portion, wherein c 1 , c 2 , c 5 , c 6 are not zero, c 2 is positive, and each of |c 1 /c 5 | and |c 1 /c 6 | is at least 0.25 and at most 0.35.