Part I: How to calculate data rates
If you’re in the process of choosing or building a digital front end for your press, you’ll need to consider how much RIPing power you need for the capabilities of the press and the kinds of jobs that will be run on it. The RIP converts text and image data from many file formats including PDF, TIFF™ or JPEG into a format that a printing device such as an inkjet printhead, toner marking engine or laser platesetter can understand. But how do you know what RIP is best for you and what solution can best deliver maximum throughout on your output device? This is the first of two posts by Global Graphics Software’s CTO, Martin Bailey, where he advises how to size a solution for a digital press using the data rate required on the output side.
Over the years at Global Graphics Software, we’ve found that the best guidance we can give to our OEM partners in sizing digital press systems based on our own solution, the Harlequin RIP®, comes from a relatively simple calculation of the data rate required on the output side. And now we’re making a tool to calculate those data rates available to you. All you need to do is to download it from the web and to open it in Excel.
Download it here: Global_Graphics_Software_Press_data_rates
You will, of course, also need the specifications of the press(es) that you want to calculate data rates for.
You can use the spreadsheet to calculate data rates based on pages per minute, web speed, sheets or square meters per minute or per hour, or on head frequency. Which is most appropriate for you depends on which market sector you’re selling your press into and where your focus is on the technical aspects of the press.
It calculates the data rate for delivering unscreened 8 bits per pixel (contone) rasters. This has proven to be a better metric for estimating RIP requirements than taking the bit depth of halftoned raster delivery into account. In practice Harlequin will run at about the same speed for 8-bit contone and for 1-bit halftone output because the extra work of halftoning is offset by the reduced volume of raster data to move around. Multi-level halftones delivered in 2-bit or 4-bit rasters take a little bit longer, but not enough to need to be considered here.
You can also use the sheet-fed calculation for conventional print platesetters if you so desire. You might find it eye-opening to compare data rate requirements for an offset or flexo platesetter with those for a typical digital press!
Fortunately, the latest version of the Harlequin RIP offers a framework that can help you to meet all these requirements. It offers a complete scale of solutions from a single RIP through multiple RIPs on a single server, up to multiple RIPs across multiple servers.
In my next post I’ll share how the data rate number can be used to make a first approximation of which class of RIP integration you should be considering.
The above is an excerpt from our latest white paper: Scalable performance with the Harlequin RIP®. Download the white paper here.
