Abstract: To check that nozzles of printheads 11-15 applying fixer or an ink to a print media 22 are operating correctly, the fixer or ink is applied to selected locations on a fluorescent print media which is then subjected to ultra-violet radiation; the reflectivities at these locations are detected in the visible spectrum and the information is analysed using appropriate image processing algorithms. In an ink-jet printer, for example, applied fixer may be irradiated with ultra-violet light by a source 30 and applied inks may be irradiated with visible light, with a common detector in the visible light range being employed.

Abstract: A test pattern is scanned to find ideal print-medium advance for a pen (or other marking device). The pattern has a medium; and, marked on it, image patches each with overlapped swaths stepped by different distances. At best there are different-color pens; and for each distance a set of patches, each with a patch for each color (preferably area fills at sensitive tones by color). All patches in a set are best adjacent along a scan direction, with alignment lines above each set across the whole pattern, and a nozzle-conditioning patch at each image patch. A processor prints the pattern, operates a sensor and uses its signals to find optimum advance. The system finds and prints with ideal advance for a most-active pen; or weighs pen activity to find an optimum for all pens based on certain statistical and/or prospective choices.

Abstract: A test pattern is scanned to find ideal print-medium advance for a pen (or other marking device). The pattern has a medium; and, marked on it, image patches each with overlapped swaths stepped by different distances. At best there are different-color pens; and for each distance a set of patches, each with a patch for each color (preferably area fills at sensitive tones by color). All patches in a set are best adjacent along a scan direction, with alignment lines above each set across the whole pattern, and a nozzle-conditioning patch at each image patch. A processor prints the pattern, operates a sensor and uses its signals to find optimum advance. The system finds and prints with ideal advance for a most-active pen; or weighs pen activity to find an optimum for all pens based on certain statistical and/or prospective choices.