Color conversion method using look up tables for compact printer system
View Patent ↗A color conversion method and apparatus for a compact printer system. An image processor converts a stored image from a first tri-color space to a second tri-color space. Resultant transformation values are read from lookup tables for each color component of the stored image pixels and a single cycle interpolator unit performs linear interpolation to generate a single color component in the second tri-color space in 14 cycles. In one example, the L*a*b* color space is converted to CMY color space. In another example, the RGB form is converted to the L*a*b* form and two extra L* components for use in sharpening a converted image.
1. A method of converting, in an image processor, from a first hi-color space to a second tricolor space, said method comprising the steps of:
reading color components of pixels of an image stored in a first hi-color space;
executing a single interpolation in each cycle so as to perform tri-linear conversion of said color components from said first color space to said second color space, said tri-linear conversion including reading resultant transformation values in lookup tables for each of said pixel color components, and performing linear interpolations on said transformation values;
completing said tri-linear conversion fix each color component of said pixels from said first color space to said second color space in fourteen cycles;
repeating said tri-linear conversion for each color component yet to be converted; and
storing said converted color components in a specific storage location.
2. The method of claim 1 wherein eight said transformation values are read from said look up tables, which require seven said linear interpolations.
3. The method of claim 2 wherein, of said seven linear interpolations, four are performed in a first dimension, two are performed in a second dimension, and one is performed in a third dimension.
4. The method of claim 1 wherein said specific storage location is a dedicated buffer for each color component of said second tri-color space.
5. The method of claim 1 wherein said method is performed on-the-fly during a print process for a converted image.
6. The method of claim 1 wherein, if said first color space is the same as said second color space, said step of performing tri-linear conversion is bypassed.
7. The method of claim 1 wherein said first color space is L*a*b form and said second color space is CMY form.
8. The method of claim 1 wherein said first color space is ROB form and said second color space is L*a*b* form.
9. The method of claim 8 wherein said step of performing color conversion is performed five times to produce two extra L* components for use in sharpening a converted image.