Details:
Summary:
A large body of research exists on tolerances for perceptible and acceptable color matches. This work is exemplified by data such as the well-known MacAdam ellipses. A common theme throughout this type of research is the use of simple fields (e.g. uniform patches on uniform neutral backgrounds) and expression of results via device-independent color designations such as CIE color spaces. A separate body of research exists on color tolerances in image reproduction. Common themes in this work include the use of complex images as stimuli and the expression of results using device-independent color designations such as density or dot percentage units. One aim of the current research was to combine the best aspects of the two bodies of knowledge to determine device-independent color tolerances for complex stimuli. This paper describes psychophysical experiments for the measurement of colorimetrically specified perceptibility and acceptability tolerances in pictorial images. The images could be manipulated in CIELab by a multiplicative factor of 0.93 and power of 1.10 and 0.92 in lightness, a multiplicative factor of 0.92 and powers of 1.12 and 0.88 in chroma, and hue angle offsets of +5.2i and -4.6i before 50% of the observers detected a change. Scene content was found to be unimportant for perceptibility tolerances, while acceptability tolerances were dependent upon scene content. Color difference formulas were also investigated. These results provide useful tools for evaluating color reproduction techniques and testing color appearance models for use in color reproduction.