An image processing system includes a profile generating section, a designating section, a calculating section and a correcting section. The profile generating section generates a color conversion profile based on first colorimetric values obtained from a first color chart output from a target device and second colorimetric values obtained from a second color chart from an output device other than the target device. The calculating section calculates difference information between a first data value obtained by converting a designated color into a device-independent color space and a second data value obtained by converting the designated color using the color conversion profile into a second color and converting the second color using the device-independent color space. The correcting section corrects the first colorimetric values based on the difference information. The profile generating section generates the color conversion profile again based on the corrected first colorimetric values.