Whenever photo material belongs to scientific publications it is very important to keep the original quality of the photo material as good as possible. It is advisable, therefore, to adjust the material to the technical necessities of the rendering process – be it a screen display or a printout. Depending on the rendering process there is big difference for the restoration process: Photo material displayed on a screen takes black as the required background color, and all other colors need to be aligned to this special background. This additive mixture of color stimuli takes advantage of the RGB color scheme. Photo material printed on paper takes white as the natural background. Since white is a mixture of all colors you need to detract colors unwanted with the help of the CMYK color scheme. The CMYK model works by partially or entirely masking colors on a lighter, usually white, background.