This paper presents the study of techniques for evaluation of digitizers quality. The evaluation parameters include characteristic curve and noise power spectrum (NPS). The most of white light source + CCD technology scanners have presented such a characteristic curve indicating an increase in intensity in their digitized images compared to the original ones. A procedure was developed to compensate the shift of each digitizer characteristic curves relative to the film’s, as a function of such responses, based on digitization process inaccuracy in pixel gray levels relative to the respective image optical densities (OD). For these cases, the proposed algorithm automatically has adjusted the digitized images pixel gray scale. As a consequence, such images could be displayed with a more accurate value of gray scale, closer to the original image. The Noise Power Spectrum (NPS) was also determined. It allowed a qualitative study of the digitizers noise level from the fluctuation in pixels values. The NPS curve was obtained by a comparative analysis between regions of interest (ROIs) of uniform images. From the developed algorithm results indicated that the laser scanner has the least noise level among all the tested equipment.