An image is processed in a device-independent color space by applying a modification function to one or more dimensions of that color space. The image is then converted into a target device-dependent color space. In order to minimize unwanted changes of color arising from the modification function taking image color values out of gamut when converted to the target device-dependent color space, the modification function is scaled to limit modified image values to within modification limits that are determined, for each image pixel or group of pixels, in dependence on the target device-dependent color space gamut boundary in the device-independent color space.