1. Apparatus for processing of an image, the apparatus comprising: a pixel input configured for handling pixels of said image, the pixel defining a local property; a reference input configured for user interactive definition of reference points; an interpolation unit associated with said pixel input, configured for applying an interpolation of attributes at a respective pixel based on said reference points; and a property assigner configured to compare a local property with said interpolation to apply a function to said local pixel based on said comparison using the said interpolated attributes, thereby to modify said local pixel.