Advanced Knowledge Base

Raster Image Processor

RIP is the acronym for Raster Image Processor and is a system that translates computer documents to a printable format. Just like the graphics card in your computer translates digital code into a viewable image, a RIP is necessary to ‘display’ digital content on paper. 

Unlike your desktop printer with a built in translator, commercial printing RIPs requires a lot more horsepower and has to tackle far more technical problems. At the heart of the RIP is the screening engine. 

Screening

In traditional multi-color printing we would expose images through color filters and very fine screens to break the continuous tone image (photograph or illustration) into a series of tiny dots. These dots are visible under magnification but at normal reading distances the human eye will blend the colored dots back into a continuous image. With the image broken down to dots and component colors we can now image that to a printing plate and subsequently put ink on paper. A RIP’s screening engine accomplishes the same thing using software. It separates the component colors of an image and then breaks each of those down to a series of different size dots placed on a very fine grid. 

Flattening

Before screening can occur the RIP needs to simplify the document. It takes all of the layers of information – text, images, objects, blends, drop shadows and so on – and flattens them down to a single layer. The RIP then examines the flattened document and creates a list of trapping instructions to pass to the separation engine. The RIP applies trapping and separates the component colors which in the case of Four Color Process Printing is Cyan, Magenta, Yellow and Black. Finally the RIP can apply screening to each of the separations. 

Imaging

The last job of the RIP is to compress the separation files and send them to a plate setter or CTP (Computer to Plate) device. This will be the subject of a future ‘What is…’ post.

Our pre-press experts are an indispensable resource available to you on any project. We are only a phone call or an email away: 770-664-8199 / prepress@advancedpf.com.

The Problem

The lower half of the graphic above represents an exaggerated example of misregistration. This is a problem that can exist in any multi-color printing process. 

Printing presses lay colors down one on top of the next. As the paper moves through the press there can be slight variations in registration – or the alignment between colors. Much of the time this is imperceivable to the reader but under certain circumstances it can be seen as gaps of white between two adjacent colors. 

Trapping

The solution to the problem is called Trapping. With this technique we create a hairline overlap where distinct colors meet. The top half of the graphic above shows an again exaggerated version of trap. The dark outline around the letters in the word “Trap” is an example of the solution. When done correctly, the trap is not noticeable and gaps are eliminated. 

Our Solution

Advanced Print & Finishing has invested heavily in our production workflow. Part of that investment is in sophisticated software that evaluates the contents of each page and adds trap as needed. 

Too little trap will result in the problem still being noticeable in certain areas. With too much trap the trap itself will become noticeable. So how do we ensure that the exact amount of trap needed will be applied? Our skilled pre-press operators review the parameters of each job and dial in the software settings. Once dialed in, the RIP takes care of the rest. We are then able to review the trap after the RIP stage and before the job goes to press. 

Our Experience is Your Experience

Always remember that our pre-press experts are an indispensable resource available to you on any project. We are only a phone call or an email away: 770-664-8199 / prepress@advancedpf.com.

Up next… What is a “RIP”?

Prepress is the term used in commercial printing for everything that happens before print production. Prepress procedures include: 

• Preflight of supplied files
• Typesetting and copy changes
• Color correction of images
• Creation of high quality, press ready PDF files
• Dieline layout
• Proofing
• Imposition
• Trapping
• Screening

Preflight can also include planning and preparation for print jobs that require finishing work.

Prepress is a necessary function that helps coordinate the needs of the printing, finishing and bindery departments with the files supplied by the customer. 

Have a Plan

The Advanced Print & Finishing prepress department has decades of experience in file preparation and work closely with customers to streamline the production process. Be sure to contact us early to discuss your next project. Chances are we can provide advise on how to save money or streamline the production process. As we say in Prepress, “a little planning can go a long way”.

Stay Tuned

Check back for additional “What Is…” posts that will describe other terms such as RIP and Trap.