Two principal systems of color proofing from separations are available: integral proofing and overlay proofing. (A 'comp' produced with a color laser printer may not be suitable as a color proof.) In both systems, each of your separations is used to create a colored image, using the appropriate color for the separation. With an integral proofing system, such as Cromalin, all four process colors are bonded to a single sheet. With an overlay proofing system, such as AgfaProof or Color Key, transparent overlays in each of the process colors are superimposed.