Filters involving derivatives with application to reconstruction from scanned halftone images

Reconstruction from Scanned Halftone Images

Data compression of scanned halftone images

A new method for coding scanned halftone images is proposed. It is information-lossy, but still preserving the image quality, compression rates of 16-35 have been achieved for a typical test image scanned on a high resolution scanner. The bi-level halftone images are filtered, in phase with the halftone grid, and converted to a gray level representation. A new digital description of (halftone) ...

Suppression of moiré patterns in scanned halftone images

Moiré patterns often appear in the image obtained from scanning an image printed on a magazine or a newspaper. The patterns do not exist in the original printing but come from alias sampling of screened halftone pictures. A strategy to design a moiré suppression scanning procedure is proposed. Fourier analysis is presented for both the screening and the scanning processes, from which a formula ...

Suppression of moiré patterns in scanned halftone images by double scans with grid movements

Moir6 patterns often appear in images obtained from scanning printings on magazines or newspapers. The patterns do not exist in the original printings but come from alias sampling of the screened halftone pictures. A new method of scanning is proposed to suppress the moir6 patterns. First, the Fourier analyses of both screening and scanning are presented, from which the new moir6 suppression sc...

Algorithms for coding scanned halftone pictures

A method of coding scanned documents containing halftone pictures, e.g. newspapers and magazines, for transmission purposes in prepress is proposed. The halftone screen is estimated and the grey value of each dot is found, thus giving a compact description. At the receiver the picture is re-screened. A new data structure and related algorithms for handling the digital screen without restriction...