Reversible coding method, reversible coding apparatus, and memory medium used therein

A reversible coding method comprising:

• a predictive coding step of separating color input image data into plural planes and processing predictive coding said data within plane or between planes in every plane,
• a modifying step of modifying the predictive error data by said predictive coding by using a correlation of predictive errors between planes, and
• an entropy coding step of coding by entropy coding of the modified predictive error data and non-modified predictive error data,
• wherein the input image data is RGB data, in said predictive coding step, the pixels of specific color plane are processed predictive coding within plane and the pixels of other color planes except for the specific color plane are processed predictive coding between planes or within plane by using the pixel values of specific color plane as reference values, and in said modifying step, the predictive errors of other color planes are modified by using the predictive errors of specific color plane as reference values, the specific color plane at said modifying step is G plane, and other color planes are R and B planes, and the modified values of predictive errors of R plane and B plane on the basis of the predictive error of G plane are preliminarily stored in the look-up table, and by referring to the look-up table when coding, the predictive errors of R plane and B plane are modified on the basis of the predictive error of G plane and coded.

A reversible coding method comprising:

• a predictive coding step of separating color image data into plural planes and processing predictive coding said data within plane or between planes in every plane,
• a modifying step of modifying the predictive error data by said predictive coding by using a correlation of predictive errors between planes, and
• an entropy coding step of coding by entropy coding of the modified predictive error data and non-modified predictive error data.
• wherein the input image data is RGB data, in said predictive coding step, the pixels of specific color plane are processed predictive coding within plane and the pixels of other color planes except for the specific color plane are processed predictive coding between planes or within plane by using the pixel values of specific color plane as reference values, and in said modifying step, the predictive errors of other color planes are modified by using the predictive errors of specific color plane as reference values, the specific color plane is G plane, and other color planes are R and B planes and said modifying step is divided into two stages, that is, at the first stage, the relation of predictive errors between G plane and R plane and between G plane and B plane of all image data is statistically summed up, the modified values of predictive errors of R plane and B plane on the basis of the predictive error of G plane are optimized, and the look-up table is compiled using said modified values, and at the second stage, using this table, the predictive errors of R plane and B plane are modified on the basis of the predictive error of G plane, and the table is attached to the coded data, and coded data is created.