1. Field of the Invention
The present invention relates to a signal conversion method and apparatus, a recording medium, and a print system, and more particularly, to a signal conversion technique for limiting the amount of color material used in a print system that forms an image on a recording medium using color materials.
2. Description of the Related Art
A printing apparatus (printing device), such as an ink jet printer or an electrophotographic printer, applies a color material (recording agent), such as ink or toner, onto a recording medium, such as a sheet, to form a desired image on the recording medium.
JP2005-101934A discloses a technique which performs an under-color removal process of replacing a predetermined amount of CMY signal, which is an input CMYK signal, with a K signal in order to prevent excess color material from being applied and to improve the reproducibility of an output image while limiting the amount of toner or ink attached to a unit area (paragraph 0005 in JP2005-101934A).
That is, JP2005-101934A discloses “an image processing apparatus that supplies an image signal to an image formation apparatus for forming an image on a recording medium using a recording agent and includes: a storage unit that stores the limit value of the total sum of the levels of image signals output to the image formation apparatus; input means for inputting CMYK signals as the image signals; first comparison means for comparing the total sum of the levels of the input CMYK signals with the limit value; under-color removal means for performing an under-color removal process of replacing a predetermined amount of CMY signals with a K signal when the total sum of the levels of the input CMYK signals is greater than the limit value; second comparison means for comparing the total sum of the levels of the CMYK signals subjected to the under-color removal process with the limit value; and an adjustment unit that reduces CMY signals after the under-color removal process by the same proportions such that the total sum after the under-color removal process is equal to or less than the limit value when the total sum after the under-color removal process is greater than the limit value” (claim 1 of JP2005-101934A).