An image processing apparatus for converting input image data into output image data for an image forming apparatus configured to output an image with the use of coloring material, which includes a unit configured to perform a coloring-material usage amount reduction process of converting the input image data into the output image data such that an amount of the coloring material used for color-printing the input image data becomes a target coloring-material usage amount defined based on a monochrome-printing coloring-material usage amount required for monochrome-printing the input image data.