quality factor

Definition: In pre-press work: multiplication factor used to ensure that graphics or image file size i.e. amount of information is sufficient for requisite quality. * The normal requirement is that file size should be sufficient for 1.25 to a maximum of 2 times the screen or output frequency e.g. for a screen of 133 lpi, the image file should have available from about 166 to not more than 266 pixels per inch of the final image (output or printed) image size. * PostScript RIPs ignore data that is in excess of 2.5 times more than the screen ruling. * Also known as halftone factor, Q factor. Q for more A common error is to work with files which have far more data that is needed for the output intended. Of course it is safer to be better than sorry. And there is no stopping the kind of person who takes the kitchen sink on a picnic. But if you want to speed up your computer, manipulate files rapidly and save on disk and other storage space, avoid crashing the RIP, and so on: then work with the smallest files you need. Try saving your files at lower and lower resolution settings and checking the print quality. You will be surprised how much you can slim a file down without obvious deterioration in quality. And with FM or stochastic screening, the quality factor may be as small as 1.

Related Terms: Nyquist rate

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