New On-line Tone Evaluation Method for Digital Photography System-5

Abstract

This paper discussed the way to evaluate the tonal characteristics of the digital photography system in terms of Camera-through Sensitometry (CTS) which has been cultivated in the traditional photography. The tonal characteristics of reproduction image on the CRT monitor shot by digital still camera (DSC) was directly measured by colorimetric analysis. The lightness data on the displayed softcopy image of lightness linear single color step charts showed linear relation with the input data level. The slope of those characteristics indicated the qualitative tone characteristics of DSC. Our previous research discussed the specific tonal features reproduced by each DSC model using the step chart of lightness. In this paper, the authors took photographs of bright cone objects and investigated the effect of DSC's tone on the bright tone analysis. As a result, it turned out that the step chart limited to the bright domain of lightness is appropriate to evaluate each DSC's tonal characteristics toward bright objects of photograph.