Image processing

Halftoning

For documents with many shade gradations (like a photograph) in full-color mode (24-bit data), you can faithfully reproduce the image on a full-color output device. Some output devices, such as 8-color PC monitors or 8-color printers, cannot faithfully portray a full-color image; however, a method does exist for approximating multiple shades on these types of output devices.

For example, by adjusting black and white pixels slightly, you can approximate various shades of gray between black

and white. This type of data processing is called halftone processing, and several versions are available on EPSON scanners. Two typical forms of halftone processing are dither processing and density pattern processing. Dither processing is the normal type of data processing found on scanners. EPSON scanners also represent halftones using dither processing.

Halftone mode A

Halftone mode B

Overview 1-21