Patent Number: 8,218,861

Title: Color quantization based on desired upper bound for relative quantization step

Abstract: A computer system processes encoded digital data representing an image at image portions. The image at each portion has color coordinates S.sub.1, S.sub.2, S.sub.3 in a first color coordinate system (CCS), wherein S.sub.1 {square root over (T.sub.1.sup.2+T.sub.2.sup.2+T.sub.3.sup.2)}, S.sub.2=T.sub.2/S.sub.1, S.sub.3=T.sub.3/S.sub.1, wherein T.sub.1, T.sub.2, T.sub.3 are color coordinates in a predefined 70%-orthonormal linear CCS. For each image portion whose color coordinate S.sub.1 is in a predefined range, the encoded digital data comprise color coordinates s.sub.1, s.sub.2, s.sub.3 such that: s.sub.1=k.sub.B(ln(.alpha.S.sub.1)+.beta.) rounded to an integer, where .alpha. and .beta. are predefined constants, s.sub.2=k.sub.efS.sub.2/S.sub.1 rounded to an integer, s.sub.3=k.sub.efS.sub.3/S.sub.1 rounded to an integer, wherein k.sub.ef is about 3--k.sub.B, or k.sub.ef is equal to the smallest power of 2 which is greater than or equal to about 3k.sub.B. The processing comprises using the encoded digital data to perform editing, and/or displaying, and/or decoding the encoded data.

Inventors: Bezryadin; Sergey N. (San Francisco, CA)

Assignee: KWE International, Inc.

International Classification: G06K 9/00 (20060101); G06K 9/38 (20060101); G06K 9/36 (20060101); G06K 9/46 (20060101); G09G 5/02 (20060101)

Expiration Date: 2020-07-10 0:00:00