A method, computer readable medium and apparatus for converting color image resolution include inputting an image enlarging ratio, inputting target pixel data of an image in a first color space to be enlarged in a sequence, sampling reference pixels including the target pixel and pixels at least one of which links to the target pixel, and converting the reference pixel data into a second color space data. Other functions include extracting image feature quantities from the reference pixel data, selecting one of a plurality of pixel multiplying methods according to the extracted image feature quantities, multiplying the target pixel by the selected image multiplying method with an integer value based on the input image enlarging ratio, and outputting pixel data that have been generated by the target pixel multiplying step in a sequence.