Patent ID: 7576888

Claim:
A color reduction processing device for converting full-color image data containing pixels, each defined by a combination of three color components, to principal color print data of which black or another specified low-brightness color is the principal color, and to secondary color print data of which a selected one of the three color components is the secondary color, the device comprising: a matrix storage unit configured to store a reference threshold value matrix; a matrix configuration unit configured to set a first adjustment value that is mathematically applied to each threshold value of the reference threshold value matrix to generate a first threshold value matrix, and to set a second adjustment value that is mathematically applied to each threshold value of the reference threshold value matrix to generate a second threshold value matrix; a principal color data processing unit configured to multiply the values of the color components of each pixel in the full-color image data by respective coefficients and add the resulting products for each pixel to produce a single weighted value for each pixel, and to compare a matrix containing all of the weighted pixel values with the first threshold value matrix to generate the principal color print data in the form of binary data; and a secondary color data processing unit configured to compare the second threshold value matrix with matrices containing color values only for the two color components in the full-color image data not designated as the secondary color respectively to generate the secondary color print data in the form of binary data.