APPARATUS FOR CONTROLLING CONTRAST DURING REPRODUCTION OF PHOTOGRAPHIC IMAGES

摘要

A method and apparatus for controlling contrast during the reproduction of photographic images from a negative or transparency. A mask is formed in a sheet of phototropic material by placing the sheet in the focal path of the image and transmitting the image to the sheet by a sheet-activating radiation source. Phototropic materials characteristically darken on exposure to a radiation source of certain wavelengths. The intensity of the radiation source may be selectively varied to produce a masking image of the desired density. The reproduction exposure is then made through the original image and the mask formed on the phototropic sheet prior to clearing of the masking image.