InDesign: Understanding the Ink Limit

I’m sure every designer has had their heart sink when they see their product marred with smudges, ghosting and other problems caused by heavy inking. It’s a common problem, especially on web presses with less than ideal stock. Thankfully you can mitigate, if not solve the problem outright – before the files are ever printed – right from InDesign!

    1. Here’s our sample document, theres a photo, some text, and a blend of 100% C, M and Y (multiply) to illustrate some of the common issues that we will need to look out for. You’d be hard pressed to spot where the problems will be unless you can check, with accuracy, which areas are flooded with ink, and which aren’t – and that’s what we will focus on today.
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    2. Select Ink Limit from your Separations Preview window, found underWindow > Output > Separations PreviewIt will default to 300%, which is the all around standard. Adobe Photoshop will default all CMYK images to have their highest ink coverage at 300%.
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    3. Looking back at our document, you may be a little confused about what all this means. Well, below is our colour blend, of Cyan, Yellow and Magenta. Each of those inks are applied at 100% (they are at their full strength). So, when two inks overlay on top of each other, our ink coverage for that area becomes 200%. The spot in the middle will then be made of 3 inks, each at 100% – meaning that area has a total ink coverage of 300%! That’s alot of ink, and this is an area that is likely to smudge on you!
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    4. When we turn on the Ink Limit, our document will temporarily change to greyscale. The light areas represent light ink coverage, dark areas are heavier coverage. Red areas are indicative of where the ink coverage is above, or equal to our threshold. At 300% you can see there are a few areas. However, I’m going to step out on a limb and immediately suggest that everyone use 250% as their Ink Limit, unless you are working on a coated stock. I’s much safer, and you will save yourself alot of grief. Of course, you will want to talk to your printer, as they may have a different value they would recommend.
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    5. Below is the same document with the Ink Limit set to 250%. Alot has changed, you can notice the image has increased it’s gamut of overlimit areas, while some areas have become a stronger red (indicating a higher overlimit ink coverage).
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    6. Some solutions to correcting our over-limit areas is to adjust the inks we use. In the example below, we could get away with setting the C, M and Y inks to only 80% instead of 100%, and get much the same effect.
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    7. Here is a common example – half of this sentence is using what the industry calls “Bad Black”, which essentially means we are creating a black using coloured inks, as well as black itself. While some circumstances may warrant this approach (particularly for dark and rich blacks), but for the most part it is to be avoided (especially with text!), a simple solution here is to use 100% black ink ONLY.
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    8. Lastly, the photo of the penguins will need some adjusting in photoshop – there is just nothing we can do with InDesign to correct this problem.Right click on the image and select > Edit With > Photoshop
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    9. Our goal is to try to lessen the amount of heavy coverage in the dark areas. I like to use the levels tool to quickly make that adjustment. By changing your Output Levels on the black end of the spectrum to 40 (the magic number with an ink limit of 250, derived from the ratio of 255/300%), we eliminate the heavy coverage. Though your image will now look a little washed out, you can reclaim some of this by adjusting your levels or curves at this time. I chose to leave them as is, for the purposes of this tutorial.
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    10. Below is our document with these changes. You can see there are still speckles of red, however they appear to be minimal, and very very close to the threshold. I would say this document will print perfectly!
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Additional resources:

  1. Creativebits.org: Photoshop Ink Limit solution (quite clever!)
  2. blog.gilbertconsulting.com: Ink Limit in other CS programs