Method of setting the contrast of a color video picture in a computer controlled photographic film analyzing system

摘要

A method of setting the contrast of a color video picture generated on a screen of a video display device from a developed photographic film image to achieve a match in visual appearance between the color video picture and an illuminated reference print of the image involves the automatic and interactive development of contrast table output values for each of three different colors in shadow and highlight regions. A base contrast table, the input value and base output value of an inflection point, and default values of user selectable contrast settings for the shadow region and highlight region for each of the three colors is stored in a computer memory and used to generate initial output values of the contrast table. The stored base contrast table, and the input value and base output value of the inflection point, in conjunction with user selected new contrast settings are employed to automatically develop new contrast table output values. The contrast table output values are downloaded to respective look-up tables which modify input electrical signals to the video display device to affect the contrast of the color video picture presented on the screen of the display device. The contrast settings can be adjusted until a match in visual appearance of the video picture with an illuminated reference print is achieved. The ultimate contrast settings of this calibration operation can be used by the same equipment in a regular analyzing mode.