Chemical imaging is a very old principle of analysis. It has been used for many millions of years in biological tasting and smelling systems. Artificial versions of chemical imaging are traditional paper chromatography and the pH indicator strip used in chemical analysis, which directly result in real (visible) chemical images. In a recent article the indirect and direct chemical imaging methods are introduced, especially the evaluation methods for gas sensitive surfaces by direct pixelizing of the surface and interface potential changes. The scanned light pulse technique (SLPT) and the scanning vibrating capacitor are very effective tools for the chemical mapping of the surfaces. These methods are sensitive for the interface or surface potential shifts (adsorption induced work function shifts) respectively, that depend on the composition of adsorbed layers. Advantages and disadvantages, some technical limits, theory, practice and some results are discussed, too. (C) 2003 Elsevier Science B.V. All rights reserved.