Apparatus and method for color transformation

• US 5,412,491 A
• Filed: 03/31/1994
• Issued: 05/02/1995
• Est. Priority Date: 03/10/1992
• Status: Expired due to Term

• Current Assignee: Kodak Limited (Eastman Kodak Company)
• Original Assignee: Scitex Corporation Ltd. (Suny Cellular Communication Ltd.)
• Inventors: Bachar, Avraham
• Primary Examiner(s): Brinich, Stephen
• Assistant Examiner(s): Grant, II, Jerome
• Application Number:
  US08/221,179
• Time in Patent Office: 397 Days
• Field of Search: 358/500, 358/518, 358/522, 358/523, 358/525
• US Class Current: 358/500
• CPC Class Codes: H04N 1/6025 using look-up tables
• CPC Class Codes: H04N 1/62 Retouching, i.e. modification of isolated colours only or in isolated picture areas only
• CPC Class Codes: H04N 1/628 Memory colours, e.g. skin or sky

Abstract

Color transformation apparatus for transforming an input color space into an output color space and including a first LUT for transforming a first portion of the input color space into a corresponding first portion of the output color space, a second LUT for transforming a second portion of the input color space into a corresponding second portion of the output color space, and a control unit for channeling input values included in the first and second portions of the color space to the first and second LUTs respectively.

Claims

1. Color transformation apparatus for transforming an input color space into an output color space and comprising:

a first LUT, including memory cells, for transforming a first portion of the input color space into a corresponding first portion of the output color space;

a second LUT, including memory cells, for transforming a second portion of the input color space into a corresponding second portion of the output color space;

a control unit for channeling input values included in the first and second portions of the color space to the first and second LUTs respectively,

a ratio of the number of memory cells in the first LUT and the number of possible input values channeled thereto differs from a corresponding ratio for the second LUT; and

at least one more LUT for transforming a corresponding one of at least one more portion of the input color space into a corresponding portion of the output color space, the control unit also being operative to channel input values included in each of the at least one more portion of the input color space to a corresponding one of the at least one more LUTs.

2. Apparatus according to claim 1 wherein the input color space portions corresponding to all but one of the LUTs include memorial colors.

3. A color transformation method for operating a color transformation on an input color space, thereby to transform the input color space into an output color space and comprising the steps of:

channeling input values included in the first and second portions of the input color space, respectively, to memory cells of first and second LUTs respectively.

employing the first LUT to transform the first portion of the input color space into a corresponding first portion of the output color space;

employing the second LUT to transform the second portion of the input color space into a corresponding second portion of the output color space,

providing a ratio of the number of memory cells in the first LUT and the number of possible input values channeled thereto which differs from a corresponding ratio for the second LUT; and

channeling at least one more portion of the input color space to at least one more LUT, and employing the at least one more LUT to transform the at least one more portion of the input color space into a corresponding portion of the output color space.

4. A method according to claim 3 wherein the first and second portions of the input color space are defined irrespective of the distribution of any particular set of input values within the input color space.

5. A method according to claim 3 wherein at least one of the first and second portions of the input color space comprises memorial colors.