An image forming system includes a color test chart that has a pattern with three tonality levels for each color component. A reading device can read the test chart as well as an original image and generates image signals representing the one of the test chart and original image thus read. A .gamma.-correcting...http://www.google.com.au/patents/US4888636?utm_source=gb-gplus-sharePatent US4888636 - Image reproducing system
