X-Face avatars: decoding needs compface's tables (licence question) #166

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opened 2026-10-19 14:22:00 +00:00 by littlefox · 2 comments

littlefox commented

2026-10-19 14:22:00 +00:00

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Split out of #151 (profiles and avatars). Avatars there are coloured initials. Showing a person's X-Face (aux item 9, which elisp shows) needs a decoder, and that raises a licensing question.

X-Face is compface's format: 48×48 bits, compressed with an arithmetic coder plus a prediction step (Gen). The prediction step is driven by large fixed tables in compface's gen.c.
There's no Rust crate, and no system library on the build machines. Decoding means porting compface: the coder is small, but the tables have to come over as they are.
compface's licence: "Permission is given to distribute these sources, as long as the copyright messages are not removed, and no monies are exchanged." NeoKOM is GPL-3.0-or-later, and the GPL allows selling copies. A port of the tables is probably a derived work, so this looks incompatible.

Options:

Don't decode X-Face. Keep initials (and later perhaps an avatar NeoKOM stores itself, which elisp wouldn't show).
Ask compface's author or maintainers for a GPL-compatible grant for the tables.
Treat the tables as functional data that isn't copyrightable, and port them. That's a legal judgement I can't make for the project.

How common X-Faces are on kom.lysator.liu.se is unknown. Counting them needs a logged-in scan, which needs your OK (D-007).

Split out of #151 (profiles and avatars). Avatars there are coloured initials. Showing a person's X-Face (aux item 9, which elisp shows) needs a decoder, and that raises a licensing question. - X-Face is compface's format: 48×48 bits, compressed with an arithmetic coder plus a prediction step (`Gen`). The prediction step is driven by large fixed tables in compface's `gen.c`. - There's no Rust crate, and no system library on the build machines. Decoding means porting compface: the coder is small, but the tables have to come over as they are. - compface's licence: "Permission is given to distribute these sources, as long as the copyright messages are not removed, and no monies are exchanged." NeoKOM is GPL-3.0-or-later, and the GPL allows selling copies. A port of the tables is probably a derived work, so this looks incompatible. Options: 1. Don't decode X-Face. Keep initials (and later perhaps an avatar NeoKOM stores itself, which elisp wouldn't show). 2. Ask compface's author or maintainers for a GPL-compatible grant for the tables. 3. Treat the tables as functional data that isn't copyrightable, and port them. That's a legal judgement I can't make for the project. How common X-Faces are on kom.lysator.liu.se is unknown. Counting them needs a logged-in scan, which needs your OK (D-007).

littlefox added this to the 0.4: Find your people milestone

2026-10-19 14:22:00 +00:00

littlefox added the

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2026-10-19 14:22:00 +00:00

littlefox commented

2026-10-19 15:06:33 +00:00

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We will do 1.

Decoding X-Face is not interesting, largely since the image is so low resolution and that the format is evidently heavily outdated since many years.

From what I can tell, X-Faces are not common at all, and the aux-item is largely vestigial.

We will do 1. Decoding X-Face is not interesting, largely since the image is so low resolution and that the format is evidently heavily outdated since many years. From what I can tell, X-Faces are not common at all, and the aux-item is largely vestigial.

littlefox referenced this issue

2026-10-19 15:11:25 +00:00

Record D-048: no X-Face avatars #167

littlefox commented

2026-10-19 15:11:26 +00:00

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Recorded as D-048 (PR #167). Profiles (#151) use coloured initials, and the X-Face aux item isn't decoded. Closing.

littlefox closed this issue

2026-10-19 15:11:26 +00:00