Patent ID: 8488221

Claim:
A printing device for printing images with ink, comprising: a printing mechanism that applies ink onto a recording medium for printing; an image data input unit that inputs original image data; a display image data conversion unit that converts the input image data into display image data for displaying an image of specified gradation values on a screen using bright spots; a printing image data generating unit that, in a particular range, by shifting the gradation value of the display image data so as to have a linear relationship between the gradation value and the output brightness, generates printing image data from the display image data; and a printing unit that controls the printing mechanism according to the generated printing image data, wherein the particular range is a range where a relationship between the gradation value of the display image data and an output brightness defined as a brightness of an image displayed on the screen based on the display image data is adjusted so that the output brightness is smaller than the gradation value of the display image data in direct proportion to the gradation value of the display image data, wherein the printing mechanism prints images using a plurality of types of ink that are different colors, and the printing image data generating unit generates the printing image data by shifting the gradation values of the display image data and converting the shifted display image data to image data expressed by the gradation values of each type of the ink, and wherein the printing image data generating unit comprises: a correspondence table in which is stored the correlation of the gradation values of the display image data and combinations of the gradation values of each of the types of ink, the gradation values of the display image data shifted, and the table storing the gradation values of each type of the inks for expressing the corrected display image data; and a unit that references the correspondence table and generates the printing image data from the display image data.