A raster image processor (RIP) is a component used in a

printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ...

system which produces a raster image also known as a

bitmap In computing, a bitmap is a mapping from some domain (for example, a range of integers) to bits. It is also called a bit array or bitmap index. As a noun, the term "bitmap" is very often used to refer to a particular bitmapping application: th ...

. Such a bitmap is used by a later stage of the printing system to produce the printed output. The input may be a page description in a high-level

page description language In digital printing, a page description language (PDL) is a computer language that describes the appearance of a printed page in a higher level than an actual output bitmap (or generally raster graphics). An overlapping term is printer control ...

such as

PostScript PostScript (PS) is a page description language in the electronic publishing and desktop publishing realm. It is a dynamically typed, concatenative programming language. It was created at Adobe Systems by John Warnock, Charles Geschke, ...

PDF Portable Document Format (PDF), standardized as ISO 32000, is a file format developed by Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. ...

, or XPS. The input can also be or include bitmaps of higher or lower resolution than the output device, which the RIP resizes using an

image scaling In computer graphics and digital imaging, image scaling refers to the resizing of a digital image. In video technology, the magnification of digital material is known as upscaling or resolution enhancement. When scaling a vector graphic image ...

algorithm. Originally a RIP was a rack of electronic hardware which received the page description via some interface (e.g.

RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' ('' data terminal equipment'') suc ...

) and generated a "hardware bitmap output" which was used to enable or disable each

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the s ...

on a real-time output device such as an optical film recorder,

computer to film Computer to film (CTF) is a print workflow involving printing from a computer straight to film through an imagesetter. Designs are typically created in Adobe Illustrator or CorelDRAW, however they can also be produced in AutoCAD, Inkscape and ma ...

, or

computer to plate Computer-to-plate (CTP) is an imaging technology used in modern printing processes. In this technology, an image created in a Desktop Publishing (DTP) application is output directly to a printing plate. This compares with the older technology, ...

. A RIP can be implemented as a software module on a general-purpose computer, or as a firmware program executed on a

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...

inside a printer. For high-end typesetting, standalone hardware RIPs are sometimes used. Ghostscript, GhostPCL, and ColorBurst's Overdrive (for

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

) are examples of software RIPs. Every PostScript printer contains a RIP in its

firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide ...

. The RIP chip in a

laser printer Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" t ...

sends its

raster image upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for ...

output to the

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The firs ...

. Earlier RIPs retained backward compatibility with phototypesetters/photosetters, so they supported the older languages. So, for example, Linotype RIPs supported CORA (RIP30).

Stages of RIP

# Interpretation: This is the stage where the supported PDLs (page description languages) are translated into a private internal representation of each page. Most RIPs process pages serially, one page at a time, so the current machine state is only for the current page. After a page has been output, the page state is discarded to prepare for the next page. # Rendering: A process through which the private internal representation is turned into a continuous-tone bitmap. In practical RIPs, interpretation and rendering are frequently done together. Simple languages were designed to work on minimal hardware, so tend to "directly drive" the renderer. # Screening: In order to print, the continuous-tone image is converted into a

halftone Halftone is the reprographic technique that simulates continuous-tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient-like effect.Campbell, Alastair. The Designer's Lexicon. ©2000 Chronicle, ...

(pattern of dots). Two screening methods or types are ''amplitude modulation'' (AM) screening and ''stochastic'' or ''frequency modulation'' (FM) screening. In AM screening, dot size varies depending on object density—tonal values; dots are placed in a fixed grid. In FM screening, dot size remains constant and dots are placed in random order to create darker or lighter areas of the image; dot placement is precisely controlled by sophisticated mathematical algorithms.

References

{{reflist Printing Printing terminology

Stages of RIP

See also

References