Spacing and kerning

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Posts: 9
Joined: 29 Sep 2021

Spacing and kerning

Post by Hoops »

Hello there,
I'm curious on how the kernOn engine works. Usually when I work on kerning it happens to change a little bit the metrics of a glyph if it seems to need too much kerning pairs. I know that it is not an orthodox way of working but for me kerning is an important step to testing spacing as well. Here is my question: when the KernOn engine is working and I change the metrics of a glyphs, the on-the-fly kern engine changes the value accordingly?

And another question: is there a strategy on how to choose models?

Thank you very much, amazing plug in indeed!
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Tim Ahrens
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Posts: 415
Joined: 11 Jul 2019

Re: Spacing and kerning

Post by Tim Ahrens »

I think it’s perfectly fine to adjust the metrics while working on the kerning. In fact, this is what I have started doing since I have been using Kern On!

Yes, you can adjust the sidebearings while Kern On is running and it will adjust everything on the fly. The only little catch is that if you use the cursor up/down keys to adjust the value this will trigger an update for every little step. It usually takes only half a second or so to re-calculate the kerning engine but it will struggle to catch up if you do the adjustments very quickly.

Note that you can also adjust the sidebearings on the Kern On window. This has a slightly different effect: If there are any models for that glyph side then their value gets adjusted accordingly. For example, if you adjust the RSB of the C by +1 then CO (if it is a model) will be adjusted by –1. This means the engine does not need to be re-calculated (as the distance between C and O stays exactly the same), and it is so fast that you can quickly step through (cursor up/down also works on the KO window). Also, you do not need to worry that you may be messing up existing models by adjusting a sidebearing. You can also use this to adjust the sidebearing of a glyph until the autokerning with a particular “neutral” glyph becomes zero. For example, adjust the RSB of the S until SH (as an auto pair) becomes zero. Using the lists for the pairs on the left or right of the H helps you find glyphs that have wrong sidebearings or need special spacing. For a sans serif, I’d also check the left side of the h and the right side of the d, as they usually shouldn’t have any non-zero pairs at all – depending on the design, of course.

As to the question of how to choose models, Kern On will give you suggestions, so that’s one strategy, of course. Another one is to look at the pair lists as described above. Plus, simply use your proofs and you will usually find necessary additional models if anything is not kerned as you think it should be.
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