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Introduction to Raster Image Processing

(February 2002) posted on Fri Mar 01, 2002

Find out how RIPs operate and what benefits they offer.

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By Mark A. Coudray

The raster image processor (RIP) is the brain behind the digital imaging process, regardless of the type of image or output device used. Here, Coudray explores the functions and features of RIPs that screen printers need to know.


The conversion of digital graphic information into a form that can be written (printed) by an output device is the function of the raster image processor (RIP). Those involved in digital prepress are familiar with the name and the concept of a RIP. But the extent of their understanding usually goes about as far as the ability to select an output device and send a file to it.


The RIP is at the heart of the digital imaging process and does all the work. The ultimate result is a printed or imaged page, panel, sheet of film, or screen. Whether we are sending an image to a laser printer or a sophisticated computer-to-screen (CTS) imaging system, the RIP delivers an array of functions. Unfortunately, many screen printers do not take advantage of the capabilities that are available to them through their RIPs.


How RIPs work


<P>The process of rasterizing an image involves converting Postscript or raster information from the original file into individual spots or dots that will be output by the imaging device.


The spot size is equal to the resolution of the output device. The RIP sends the information to the device through control software known as a driver, which is specific to each individual output device (we need the appropriate driver for each device the RIP drives). Until relatively recently, we would have needed a separate RIP for each output device we were running. But this is changing to reflect more efficient imaging workflows in which we will RIP a file once, and output it to multiple devices. For example, we could process an image for producing film positives and use the same processed image to produce an inkjet proof.



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