Image scanning apparatus and method

Abstract

Scanning apparatus having at least one self scanned array; a multispeed transport for carrying documents to be scanned past a scanning slit where the moving document is scanned line by line by the array at high speed on the assumption that most documents are composed of lines or text; processing the image signals produced by a line processing means; while scanning, using halftone and continuous tone detectors to look for halftone and continuous tone images respectively; where halftone images are detected, rescanning the line at low speed and processing the resulting image signals by a halftone processing means and thereafter reverting to high speed scanning; and where continuous tone images are detected, rescanning the entire document page at low speed and processing the resulting image signals by a continuous tone processing means and thereafter reverting to high speed scanning. Optionally, to enhance system operation, sub-sampling of the document being scanning when scanning at high speed may be performed.

Dependencies are inferred from the claim text.