In order to obtain a good quality image in preparation for inkjet printing, the process of adjusting images can be a time
consuming and a costly procedure. In this paper, we consider the use of an unsupervised colour enhancement method as
part of the automatic pre-processors for printing. Other unsupervised colour enhancement methods are utilised and
compared: Retinex, RSR, ACE, Histogram Equalisation, Auto Levels. Test images are subjected to all of the
enhancement methods, which are then printed. Users are asked compare each of the sampled images. In all cases, the
results are dependent on the image. Thus, we have selected a range of test images: photographs of scenes, reproduction
of prints, paintings and drawings.
Some of the tested methods are parameter dependent. We do not intend to consider fine tuning for each of the
techniques, rather to consider an average parameter set for each one and then test if this approach can aid the decision
process of fine tuning.
Three user groups are employed: the general user, commercial photographer expert and fine artist. Groups are asked to
make a blind evaluation of a range of images (the original and the colour enhanced by the different methods); these are
randomly placed. All images are printed on the same printer using the same settings. Users are asked to identify their
preferred print in relation to lightness, tonal range, colour range, quality of detail and overall subjective preference.