The characterization of photoresists during the image formation process has traditionally relied on bulk methods during or after development. This article shows that it is not necessary to develop the photoresist in order to obtain significant information about the image formation process in x-ray, electron beam, and UV lithography. The characterization of the image formation process in chemically amplified photoresists prior to development is difficult due to their sensitivity to electrons used in scanning electron microscopy and the weak changes in dielectric constant needed for optical microscopy. The advent and development of the atomic force microscope (AFM) have allowed local surface measurements of exposure induced changed in photoresists with sub-mu m scale resolution and negligible modification of the sample. A series of chemically amplified resists, positive and negative, have been studied with a variety of exposure radiation (electron beam, x-ray, and UV). The results discussed in this article focus on two of these resists : SAL 605 (-), and TOK 010 (+). Both positive and negative chemically amplified resists exhibit significant changes in topography and calorimetric properties during the image formation process. Interpretation of the resist topography in negative resists is given by a semi-empirical model that assumes Fickian diffusion of resist material during post-exposure bake (FEB) and verified with AFM data. The glass transition temperature, Tg, of wafer spun thin films of SAL 605 has been measured, prior to exposure, to be 75+/-3 degrees C with an ellipsometric technique. The FEB temperature, 105 degrees C, is much greater than the Tg of SAL 605, thereby providing some justification for our Fickian diffusion model. These results are preliminary until a chemical map can be done on the resist at sub-mu m resolution, which at present time is not possible. The need for detecting intrinsic material property changes due to the image formation process motivates the exploration of calorimetric properties of the resist. Interpretation of the calorimetric data is still unclear. Both cases of positive and negative photoresists exhibit an increase of heat absorbed in the exposed regions. Photoacid ions produced by exposure to radiation may be considered responsible for such an increase.