This paper describes a prototype of a complete CADx system developed in the last years in our research group. Its basic structure consists of pre-processing corrections based on the image acquisition and digitization procedures (FFDM, CR or film + scanner), a segmentation tool to detect clustered microcalcifications and suspect masses and a classification scheme, which evaluates the presence of microcalcifications clusters and possible malignant nodules based on their contour. The aim is to provide enough information not only on the detected structures but also a pre-report with a BI-RADS classification. With the absolute prevalence of digital images in mammography several new tools became available for radiologist; such as CAD schemes, digital zoom and contrast alteration. This work focuses in contrast variation and how the radiologist reacts to these changes when asked to evaluated image quality.