Method of controlling exposure of process camera

An apparatus for controlling exposure in a process camera at the time of obtaining dot image by exposing image of an original onto a photosensitive material through a screen, said apparatus comprising:

• basic data storing means for storing basic data obtained with respect to a predetermined reference original and the screen and original data,
• means for storing data for correction for determining a correction amount of said original data to obtain dot image having desired contrast,
• measuring means for measuring a dot percentage difference .delta..sub.H between a dot percentage of a highlight region of a first dot image obtained by photographing the original by using the exposure of an amount determined based on said basic data and said original data and a desired dot percentage of a highlight region, and a dot percentage difference .delta..sub.S between a dot percentage of a shadow region of said first image and a desired dot percentage of a shadow region,
• basic data updating means for updating said basic data by acquiring a correction amount of said original data for obtaining second dot image having desired contrast based on said dot percentage differences .delta..sub.H and .delta..sub.S and said data for correction, said basic data being updated based on the obtained correction amount of the original data, and
• exposure amount re-calculating means for recalculating an exposure amount necessary for obtaining said second dot image based on said updated basic data and said original data.