Patent ID: 7023582

Claim:
An image processing apparatus for subjecting color image data constituted of three primary colors to black ink addition, said apparatus comprising: identifying means for identifying a pixel attribute of each pixel in said color image data and outputting a pixel attribute signal; first address generating means for generating a first address based on a difference between a maximum value and a minimum value among three values indicating the three primary colors for each pixel in said color image date, and said minimum value; a first lookup table in which first data and second data are read from the first address generated by the first address generating means; linear interpolation means for outputting data used as a black ink signal and interpolating said first data and said second data read from the first lookup table; second address generating means for generating a second address based on the three values indicating the three primary colors for each pixel in said color image data; a second lookup table in which data used as a black ink signal is read from the second address generated by the second address generating means; and black ink signal selecting means for selecting/outputting either one of said data used as a black ink signal read from the second lookup table or said data used as a black ink signal outputted by said linear interpolation means in accordance with the image attribute signal of the pixel outputted from said identifying means.