Effects of Certain Imaging Errors in Computer-to-Press Systems

Certain types of imaging errors that might arise from electrical or electromechanical disturbances in a computer-to-press system have been simulated and used in perceptual tests with human subjects. Displacive imaging disturbances have been categorized according to whether they occur parallel or perpendicular to raster scan lines, and whether they occur in the direction of scanning or opposite to it. The effects of such scanning errors on the quality and legibility of tests printed using Western, Middle-Eastern, and Asian character sets, and on the quality of halftones, were investigated. The detectability of the errors and their effect on legibility were found to vary somewhat according to the language of the test. In the case of halftones, it was observed that subtle changes could be produced in such a way that an observer might receive altered information without suspecting that an error had occurred.