This glossary of printing terms was created by people working in today's printing industry and is brought to you by MirPrint.com. It has been revised and edited and we have rewritten some technical descriptions in every day language to help the non technical person. Any suggestions that you may have on how we can improve this glossary will be carefully considered. Please send your comments and any new definitions to us at MirPrint.com.
Raster Image Processor
Depending on the application, accuracy of registration may be more or less necessary. See Absolute Register, Close Register, Commercial Register, Hairline Register, Lap Register, and Loose Register. Inaccuracies in registration are known as misregister. Process color printing is usually performed utilizing register marks, small shapes on successive plates which aid in the setting of proper register.
Screen resolution can refer to both the color depth (i.e., 8-Bit color vs. 24-Bit color, or the total number of colors that can be displayed) and intensity of the displayed image, or to the number of pixels displayed per unit of length. (Though not really a measure of resolution per se, a monitor's dot pitch is a measure of the diameter of one screen pixel. The smaller the dot pitch, the greater the resolution.) When describing vector displays, screen resolution refers to the number of horizontal lines per inch. When describing raster displays, screen resolution refers to the number of horizontal and vertical pixels that can be displayed (i.e., 640 x 480).
Although dots per inch is commonly used as a measure of output resolution, a more preferable measure is of the number of discernible line pairs per inch (or millimeter), as in many types of output the dots are deliberately made to overlap, skewing the "dots per inch" measurement.
In desktop publishing, "dots per inch" or, more correctly, pixels per inch (to distinguish pixels from halftone dots), is the measurement of choice, and is the unit most often used in input and output device specifications. For example, a Macintosh monitor has a resolution of 72 ppi; a laser printer has a maximum resolution of 300:600 ppi; and an imagesetter has a resolution of 1270:3386 ppi. On the input side of things, a desktop scanner has a resolution of 300:600 ppi, while a high-end drum scanner has a resolution of up to 10,000 ppi. Resolution, therefore, is a combination of both the input resolution and the total number of dots (actually, more correctly called spots, to, again, distinguish them from halftone dots, which are themselves composed of printer spots) that the output device can print per inch.
As a general rule, the higher the resolution the better, but there is a caveat. Although scanning an image at the highest resolution that the device will allow may seem like a good idea, it is in vain if the output device's resolution is lower. And since digital file size increases with increasing resolution, one may be doing oneself a disservice by scanning higher than one needs to, which will result in longer image processing time, larger file sizes, and more RAM needed to work with the image.
The term reverse also refers to type or other matter that is designed to print as white on black (or colored), rather than as the typical black on white.
The term reverse should not be confused with the physical reversing of the orientation of an image, which is more correctly known as flopping.
A rotary press is also used to specifically describe a type of cylinder-based press used in letterpress printing.