Monday, June 16, 2008
Preparing images for print - commercial printing part 2
The first dialog box should be familiar enough, the Color Settings box (Edit>Color Settings). We've used this dialog to help with our colour management routines. Until now, we've probably ignored the CMYK drop-down menu, or kept it at the default [US Web Coated (SWOP) v.2]. SWOP stands for Specifications for Web Offset Printing. I can already hear the confusion ... in this case, the Web portion has nothing to do with the internet or a delivery method. Web presses are fed by large rolls of media. This is opposed to sheet-fed presses. The advantage of web printing is that you can run job after job without regard to the final size of the project - keeping the presses rolling. Jobs are cut down to size later in the process. With sheet-fed, there is more hands on time as media is changed from job to job. This works best for specialty printing projects and custom media types.
After working the image as you would in the forensic photoshop workflow, it's time to start thinking out output. (Remember, we always work from copies.) Our first call or e-mail will be to the printer or the publication's contact person with the most knowledge of their printing process. We'll want to know the line screen of the final print, that is to say how many lines per inch. I know, we're used to thinking in dpi. This one is simple though, for lpi just divide dpi by 2. If your target is 150 line screen, then your final image should be 300dpi. Remember that interpolation is handled towards the end of our workflow.
Going from a 72dpi screen grab of a DVR video to camera ready art can be tricky. I'll refer you back to our discussions on interpolation earlier in the blog (use the search box above). If you don't interpolate to 300dpi, your images will come out overly pixelated when printed - or the printer may reject them outright.
If your printer has a custom profile, try to get it from them. Many of the higher-end print shops do now (and many are using direct to press digital technology). But, many magazines and newspapers contract out the printing and may not have access to their presses anymore, so don't rely on this entirely.
Take a look at samples of the publication. Look at the images that are printed. Are they over or under saturated? Do they look out of focus? Can you see the screen or moire pattern? This will give you clues as to how to output your images so that they will look their best.
In the next installment, we'll look closer at getting our files ready for print.