The present invention provides an image processing device that avoids
occurrence of unintended color conversion during the logical operation
processing, and produces high-resolution images. In the image processing
device of the present invention, after an input color conversion unit
converts the RGB color space into the CMYK color space, a first color
conversion unit executes color conversion of an area subjected to the
logical operation processing into the CMY color space, and a logical
operation unit executes the logical operation processing. Thereafter, a
second color conversion unit executes color conversion of a logical
operation result into the CMYK color space. On the other hand, a pixel
value comparison unit compares the color values of the CMY color space
before and after the logical operation by the logical operation unit; and
if coincident, an output image selection unit selects the color values
converted by the input color conversion unit as they are. Thereby, as a
result of the logical operation, if the color values of the images are not
varied, the original color values in the CMYK color space are adopted as
the output result; and therefore, there will not be unintended color
conversion executed by the first and second color conversion units.