Layering FontForge’s Metrics Window
Barry Schwartz suggested on the fontforge-devel list that “it would be useful to me to be able to put a bitmap image in a background layer of the metrics window.” George Williams asked, “Can you explain why this is worth the work? Why do you want an image there, that window isn’t intended for glyph design.”
Here are my thoughts:
The metrics window is used for metrics design; if you are doing a type revival from a scanned page and you want to get as close as possible to the original metrics, this would be useful because you could take small cropped sections of that image and drop it in as a background image in the metrics window and then line up the outline glyph’s metrics appropriately.
I think a more automated approach is certainly possible, where another program would segment the page’s letters into pairs or triplets or quadlets or … and have them classified by Optical Charachter Recognition (and by hand); then a complementary FontForge script to process the images and classification list to instantiate a series of metrics windows with each pair image and the corresponding glyphs.
(Raph wrote a program for segmenting scanned sheets into single glyphs, from which I get this idea)
Barry explains his current method:
Instead of Raph’s approach, I automatically cut the text into lines (rather than glyphs), do some ad hoc GIMPy stuff that gives me some idea of the impression, the spread, etc., and load an entire line into the glyph window. (I don’t do any averaging; I tried it and rejected the approach, at least for what I am currently doing.) I wanted to be able to load the lines into the metrics window as well, but it turns out to be more practical, for me, to work as follows: if I am working on right side bearing of “r”, let’s say, and I already have the left side bearing of “n”, I can put the image of the word “turn” behind the “r”, copy an “n” into the “r” window, put it over the “n” in “turn”, and then measure the distance between the letters. The glyph window is much better than the metrics window for this.
Thinking about things, it seems that reverse-engineering metrics from printed matter is made complex by kerning exceptions.
The Layering FontForge’s Metrics Window by David Crossland, except the quotations and unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License.
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