Gradation correcting method and apparatus

摘要

A fundamental gradation curve is enlarged or reduced such that the minimum density and the maximum density represented by the fundamental gradation curve may be changed respectively to a desired minimum density and a desired maximum density. The enlarged or reduced fundamental gradation curve is translated such that a point corresponding to a predetermined density may be shifted to a point representing a desired density. The translated fundamental gradation curve is rotated around the point corresponding to the desired density such that this point may represent a desired contrast. The enlarged or reduced fundamental gradation curve and the rotated fundamental gradation curve are weighted and added such that the minimum density and the maximum density represented by the rotated fundamental gradation curve may be changed respectively to the desired minimum density and the desired maximum density, and such that the point corresponding to the desired density may represent the desired density and the desired contrast. A desired gradation curve is thereby obtained. <MATH>