1. An image processing method, comprising: first converting input image data from a source color space to a converted image in a target color space having a linear brightness color component and other color components, the brightness color component being orthogonal to the other color components; second converting the brightness component of the converted image data from the linear representation to a perceptual representation; altering the converted brightness component of the converted image data according to control parameters derived from viewing conditions of an output device; third converting the altered brightness component from the perceptual representation to a linear representation; and fourth converting the altered linear brightness component obtained from the third converting and the other color components obtained from the first converting to a color space of the output device.