In an image processing device for recording images with Y, M, and C color ink, a received Bk image is recorded with a color more similar to an original black color and solves a problem caused by too much amount of ejected ink such as bleeding with other colors or feathering. An image data consisting of four color elements of YMCBk is entered from a host computer, a Bk conversion unit converts the Bk element to respective Y, M, and C elements by masking of respective Y, M, and C elements generated randomly for the entered Bk element image data, and an image synthesizing unit synthesizes the converted YMC elements with the entered YMC elements. Then, an image recording unit for forming an image with three colors of YMC forms an image based on the synthesized YMC elements and records the image on a recording medium with ejecting YMC ink from a recording head.