Abstract: Image quality assessment test charts and objective image quality measurement systems may be used to evaluate the printer sub-system health before artifacts become objectionable to human observers. Diagnostic images may be printed to allow measurement of a number of system performance attributes, such as: density, banding, streak, granularity, mottle, color, gloss, gloss uniformity, edge gradient, raggedness, sharpness, background, registration, line width, and satellite measurements. By comparing these measurements to historical values or ideal values of the same measurements, preventive maintenance suggestions may be generated to avoid both unnecessary maintenance and objectionable print quality.

Abstract: A copier or a printer 10 includes a controller 16/30 with a rendering algorithm that groups sets of adjacent pixels into sets of adjacent cells where each cell corresponds to a halftone dot of an image. The algorithm operates in conjunction with a gray scale printhead 22. In sending data to the printhead, the controller 16 parses a scanned image and set the exposure for each pixel in accordance with a growth and density program. The algorithm selectively grows halftone dots from zero size to a desired size equal to or less than a maximum size. It repeats this step for the rest of the pixels until the cell is at its desired size and at an initial density. If a higher density is desired, the algorithm selectively adjusts the fully grown cells by sequentially increasing the level of exposure of each pixel in the cell. The image is developed with developer including a hard magnetic carrier and toner.