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Getting the Upper Hand on Challenging Images

(November 2010) posted on Fri Nov 05, 2010

An exploration of the intricacies of different image types and output options.

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By Jared Smith

We’ve learned the expensive way that there are many good reasons to always make sure your RIP software version was released after your software applications – older RIPs can’t effectively handle files generated from new graphic applications. If you opt to use an older RIP, you’re likely to have serious issues with color-space discrepancies and in other areas such as mishandled gradients where hard lines appear. Make sure you upgrade the RIP.

Another area of concern with vector files is related fonts or, in our lingo, “live fonts.” The phrase refers to text copy that can be edited with any text tool or text-format options. If a client provides a vector file, we recommend they outline the font. This process changes the text from editable characters to shapes that can no longer be edited by the text tools. If your application does not have a certain font used in a submitted file, it will ask you if you would like to substitute a different font, thus changing the client’s desired look. Therefore, requesting that files come to you with fonts outlined can avoid some potential pitfalls.

Masks, transparency overlays, and gradients are additional file elements that can cause issues if not handled correctly. Flattening layered raster files to a single-layer TIFF file will usually alleviate possible problems here. Another particularly tricky image issue is the presence of alpha channels. Put in simple terms, alpha channels are a type of mask you can save and load that RIP software has trouble with. If you have a peculiar issue that you can’t seem to track down, inspect the file for alpha channels and take the necessary steps to flatten that file and/or remove alpha channels. This issue only shows itself once a year or so at our shop.

Color space is another area you should have under complete control. Color space refers to the methodology that your file source (e.g., Adobe Illustrator) and your RIP use to handle color. The best way to explain color space is to look at a Pantone color example. If you add PMS 185 red to your file, and process it with your RIP, the RIP’s task is to recognize that your intention was PMS 185 red and adjust the CMYK values based on the latest media profile and linearization results to get the closest match possible to PMS 185 red on the selected media. But if the file was created in a different color space than the RIP is using, the desired output will not be well defined and the results will show it.

If you have supplied the RIP with a PDF, EPS, or flattened CMYK TIFF file created in the same color space as your RIP with no live fonts or alpha channels, then you’ve covered the most critical areas.

The best shortcut
Other image factors can also prove daunting. For instance, printing neutral gray – meaning no cyan, magenta, or green tint – is always a challenge. You can correctly prepare the file, have your color space under control, and your media profiles and linearizations current, but the temperature and humidity on that day can still affect your final output.

Skin tones and very light colors are also challenging because they contain such a low amount of each CMYK color that banding (those nefarious visible lines caused by each pass of the print carriage) can appear in the print. On the other hand, a deep rich black contains a high value of each CMYK color; with this much ink on the media, it’s much easier to avoid banding.

Study your craft and keep in mind that diligent, hard work is always the best short cut. Soon, you’ll get the upper hand on even the most challenging images.