1. An image processing apparatus which converts input image signals into output image signals represented as a combination of colored colorant amounts and colorless colorant amounts, the apparatus comprising: a determination unit configured to determine for each pixel of an input image represented by the input image signal, whether the pixel is belonging to a high density range or a low density range; a specification unit configured to specify for each pixel belonging to the high density range, whether the pixel is belonging to a high frequency range or a low frequency range; and a generation unit configured to generate the output image signal by applying color conversion with a 1st conversion parameter to an input image signal corresponding to a pixel belonging to the high frequency range, and applying color conversion with a 2nd conversion parameter to an input image signal corresponding to a pixel belonging to the low frequency range, wherein a colorless colorant amount for an output image signal generated by the color conversion with the 1st conversion parameter is larger than a colorless colorant amount for an output image signal generated by the color conversion with the 2nd conversion parameter.