Apparatus and method for the reproduction of colored originals with gray balance and/or contrast adjustment

摘要

A colored original to be copied is scanned point-by-point in each of the three primary colors red, green and blue. A series of imaging signals is generated for each primary based color on the scanning operation. The signals are subsequently converted into a colored optical image of the original by means of a cathode ray tube which prints the image on color copy material. Prior to conversion, the signals are processed to electronically enhance the image. Following electronic image enhancement, the signals are adjusted to the characteristics of the copy material. The adjusted signals are now modified so as to make them proportional to the illumination intensity of the cathode ray tube or to the logarithm of the illumination intensity. The modified signals are next corrected to adjust the gray balance and/or the contrast of the image. This is accomplished either by multiplying each series of modified signals with a respective correction factor or adding a respective correction factor to each series of modified signals. The signals are thereafter fitted to the characteristic function of the cathode ray tube which then prints the image.