Chromatic font research. (derives from Re: Ethiopic chromatic fonts)

From: William Overington (
Date: Mon Jun 24 2002 - 03:16:27 EDT

Marco Cimarosti wrote:

>*If* there was a real need for such a feature, I think that it should be
>implememted at the level of single contours, rather than at the level of
>whole glyphs.
>For instance, a "color" attribute could be added to each contour composing
>glyph. In True/Open Type terms, this would probably mean changing table
>"glyf". If two (or four) colors are enough, the new "color" attribute could
>be fitted in one (or both) reserved bits in the contours' "flags". Of
>course, the color attribute would be meaningless and unused for countours
>defining "holes".

I wonder if I may suggest four colours as default colours for rendering
engines to interpret the meanings of the four possible colours please.

00 black
01 red
10 green
11 blue

Also, as a contribution to the research discussion, I wonder if I may
suggest the following test item.


This will hopefully be useful as a test item and also suggests a way of
representing designations of code points in terms of the default colours,
with the convention that if the colour is not stated then it is black.


Naturally, changing the default colours of a rendering engine is another matter, whether that is done manually, by markup or by code points is for discussion.

However, hopefully this suggestion of four default colours and of a test code point will be helpful for anyone wishing to research in the area of chromatic font technology.


Fonts for regular Unicode characters, such as alphabets, could also be implemented as chromatic fonts if so desired. This could be very effective in some ornamented display fonts. There could be such packages as a desktop publishing package reading in from a Unicode file using a chromatic font, or reading from a plain text file for features such as a holly border.


I am also looking at the possibility of three-dimensional fonts, where the contours within the font are not line contours but are closed surfaces. I am looking at how one can use Bezier surfaces to describe such a closed surface. I am thinking about the possibilities for practical application of three-dimensional fonts. One particular application is for overhead display signs for logos such as a payphone point and so on. Symbols to be codified for such three-dimensional fonts would need to take into account the need to be viewed from various directions, yet could be rather more elaborate than simply solids of revolution of a flat shape. Although such items could not be displayed upon paper as such, nevertheless as they would be represented in computer equipment perhaps they should be codified in a Unicode compatible manner. A symbol for a payphone point could be made in plastic and be a permanent display graphic. The possibility exists that some three-dimensional symbols could be displayed using a display system, so that the displayed symbol could be changed from time to time using an electronic signal sent to the display unit.

William Overington

24 June 2002

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