What is a RIP anyway?

[blue moon]

RIP (raster image processor) is a program that provides several functions needed to generate the screenprinting films.


1. it converts the grayscale in the image to halftone dots. This allows the reproduction of photo type art to be printed with a screen.
here is an example:

copyright scott fresner/t-biznetwork

2. It controls the amount of ink deposited on the film (for ink-jet printers). Most printers used for the film positive generation allow for different amount of ink to be deposited with each droplet. This function, on a basic level, compensates for different types of film and their ability to absorb the ink. More sophisticated programs will actually allow for compensation based on the halftone percentage (for example, depositing less ink in the middle range where the likelihood of dot gain is higher. Or if the films are not dark enough in the shadows, ink volume can be increased there without influencing the snaller dots)

3. Provides Post Script Language for the printers that are not compatible with it. Most of the InkJet printers are not equipped with a Post Script Language needed to interpret the halftone results to printhead commands. In this case, RIP software translates the percentage dots generated by conversion and it directs the printer (or in some cases the printhead directly) how to eject the ink.

[Dottonedan]

ooooh!  Look at you!  Mr. "can do" too.

[dlac]

I thought it was people put on headstones...
LIKE
R.I.P
Here lies someone... you know
dlac

[RichardGreaves]

I wrote this article for Specialist Printing, the ESMA magazine in 2007.

http://www.ulano.com/ijf/whatdoesaripdo.htm

http://www.specialistprinting.com/index.htm

[blue moon]

I wrote this article for Specialist Printing, the ESMA magazine in 2007.

http://www.ulano.com/ijf/whatdoesaripdo.htm

http://www.specialistprinting.com/index.htm

Hey Richard, can we post that on here if we give Ulano the copyright credit and a link?

pierre

[RichardGreaves]

I did post this on the Ulano site when I was their webmaster, but they have no rights at all.

The article is mine. I wrote it on my own time. 

Use it anyway you wish, credit to me and mention Specialist Printing.  I have many more pictures and a PDF of the actual article.

[squeezee]

Welcome Mr. G, good to see you around.

I'd like to add that RIPs support trapping.
They can also do some wonderful things like hybrid screening etc.

[squeezee]

I did post this on the Ulano site when I was their webmaster, but they have no rights at all.

The article is mine. Use it anyway you wish, credit to me and mention Specialist Printing.  I have many more pictures and a PDF of the actual article.

Anything I worked on, or thought of, during my term of employment at your competitors became their property.  Luckily for me that amounted to practically nothing 

[prozyan]

I think an interesting discussion, in addition to what a RIP does, would be to talk about when a commercial RIP becomes necessary for a shop.  There are a lot of smaller shops out there printing 3 or 4 color designs with basic halftones that can use something like Ghostscript and have zero problems.  I know Frog uses GS, as do I.  At which point should someone start looking toward a commercial RIP?

[squeezee]

My twopence worth would be when the throughput justified it.  I never think that it's reasonable to spend more on the RIP than your printer.

[Northland]

I think an interesting discussion, in addition to what a RIP does, would be to talk about when a commercial RIP becomes necessary for a shop.  There are a lot of smaller shops out there printing 3 or 4 color designs with basic halftones that can use something like Ghostscript and have zero problems.  I know Frog uses GS, as do I.  At which point should someone start looking toward a commercial RIP?

I've seen films from GS and when compared to FilmMaker films I'd say... today is the day to make the switch to a commercial RIP.

My thought is:
There are so many variables in screen printing, why not try to eliminate as many as possible ?
Waterproof film and a good RIP will just about eliminate film density/exposure issues.

[yorkie]

2. It controls the amount of ink deposited on the film (for ink-jet printers). Most printers used for the film positive generation allow for different amount of ink to be deposited with each droplet. This function, on a basic level, compensates for different types of film and their ability to absorb the ink. More sophisticated programs will actually allow for compensation based on the halftone percentage (for example, depositing less ink in the middle range where the likelihood of dot gain is higher. Or if the films are not dark enough in the shadows, ink volume can be increased there without influencing the snaller dots)

Your wrong on point 2. A "RIP" is a Raster Image Processor, constructs a "raster image". In a postscript rip which generates halftone dots, the function which varies the size of the dot is built into every postscript rip, not just the high end ones. This is true all the way back to postscript level 1.

Printing the raster image blacker on an inkjet printer is a function of the device driver. Most people who use ghostscript use gsview to generate a raster image, then use the standard windows device driver to output the film. The windows driver does not offer the option to print at double density, but does allows darker printing than the drivers default settings.

Features such as trapping and imposition are performed between the RIP process and the device driver output.

[RichardGreaves]

My use for a screen printing RIP is to increase UV density of the transparent Epson black ink designed for photographs and control the final halftone size even with all that ink. This purpose for screen printing is unique.

[Evo]

http://en.wikipedia.org/wiki/Raster_image_processor

A raster image processor (RIP) is a component used in a printing system which produces a raster image also known as a bitmap. The bitmap is then sent to a printing device for output. The input may be a page description in a high-level page description language such as PostScript, Portable Document Format, XPS or another bitmap of higher or lower resolution than the output device. In the latter case, the RIP applies either smoothing or interpolation algorithms to the input bitmap to generate the output bitmap.

Raster image processing is the process and the means of turning vector digital information such as a PostScript file into a high-resolution raster image.

So at the core of all RIPs is the above function. Processing image and page description information into a bitmap file that can be sent to the printer driver to be printed on an inkjet.

What sets apart commercial RIPs, epsecially those produced with screen printers in mind, is the way the RIP is implemented and enhanced. For example, I use Accurip - it loads as a system service on the computer so it is always on and ready like a printer driver is (they call it a driver-based RIP). Also, it can override the stock print driver and graphic application settings and do some cool stuff (multi black carts, locking screen angles and LPI, auto n-up, etc)

But yeah, at the core, a RIP is a RIP.

[squeezee]

If you use a Windows driver you will get rich-blacks composed of CMY&K.  A RIP will use a monochrome black - just the black ink which has the highest uv density.