Exposure calibration for colour recorder or printer - involves computation of darkening function for nominal grey values for determn. of corrective transfer function

摘要

A front-end computer (10) comprising a scan generator (10') and calculation stage (10'') is used with a raster image processor (11), recorder (12), film processor (13) and measuring device (14). A transfer function is determined from pixel-by-pixel and line-by-line exposure of the recording material, using a linearly patterned scan and measuring the surface coverage of the developed pattern. Relative darkening increases are used to derive the effective increase of a scanning point with allowance for provided scan parameters. ADVANTAGE - Nearly automatic calibration can be performed with greater accuracy in shorter time, relieving operator of routine tasks.