Method and apparatus for forming color images by converting a color

Abstract

Method and apparatus for forming color images on paper using a sublimation type thermal transfer full-color printer using three color inks of yellow, magenta, and cyan. A color input signal to be printed is subjected to a first color correction process. The first color correction process performs a color correction using linear and non-linear masking operations and produces first ink-density signals. The first ink-density signals are judged for reproducibility by the printer by determining whether the signals fit within a gamut of colors. If judged to be reproducible, the first ink-density signals are passed on to the printer. However, if the first ink-density signals are judged to be outside the gamut of colors, the signals are subjected to a second correction process. The second color correction process first obtains a target color for color reproduction by the printer. Next, the second process sets ink-density signals, obtains predicted colors realized by the ink-density signals, chooses an output ink-density signal such that an evaluation value calculated by the target color and the predicted color becomes minimal, and produces a second ink-density signal that results in optimal colors within the range of colors reproducible by the printer.