| 摘要 |
A gray balance correcting method in which the deterioration of color balance correcting capacity can be avoided for an image photographed under different kinds of light sources, such that the influence of failure can be eliminated. An image recorded on a negative film is divided into a large number of regions. Density values of C, M and Y in the respective regions are measured. Maximum and minimum reference values for the C, M and Y colors are calculated based on the measured density values D. Then, conversion correlation coefficients, for the respective colors, are calculated to make values, after conversion of the reference values of the respective colors, coincident with Dmax and coincident with Dmin. The measured density values of C, M and Y are converted by using the conversion correlations determined from the calculated coefficients. In another embodiment, only maximum values are used as reference values. In yet another embodiment, the converted measured density values are plotted on color coordinates. Then, averages in a predetermined region S containing a line L passing through the maximum and minimum converted reference values, Dmax and Dmin, are calculated based on the distribution plotted on the color coordinates. Conversion correlations of the respective colors are corrected according to curves of secondary degree PC and PY passing through Dmax, Dmin and the average of the density values. The C, M and Y measured values are then converted again by using the corrected conversion correlations.
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