#228 converting multi-layer ICO file with opacity

[Martin Erik Werner]

Redirected from graphicsmagick-help
https://sourceforge.net/mailarchive/message.php?msg_id=30625546

GM does not seem to handle ICO files, in particular with opacity and/or(?) multiple layers very well.
If an index [n] is specified without +adjoin, only the zeroth layer (regardless of the index given) seems to be extracted, and opacity information is discarded.
If +adjoin is given, either with an index or with a printf pattern, the given image(s) are extracted and opacity information is discarded.

I would expect extraction by index to work without +adjoin, and for opacity to be preserved.

I'm using this source file:
https://sourceforge.net/apps/trac/redeclipse/browser/src/redeclipse.ico
and:
GraphicsMagick 1.3.16 2012-06-23 Q8

[Glenn Randers-Pehrson]

With GraphicsMagick 1.4 snapshot-20130213 Q16,

gm convert redeclipse.ico +adjoin red%d.png

I get red0.png through red3.png, all having transparency.

Same with GraphicsMagick 1.2 that happens to be on my system.

Without the +adjoin then I only get one output file with gm-1.4 but the expected 4 files with gm-1.2, even when I don't use a printf-style numbering.

The printf thing doesn't work with 1.4 when +adjoin isn't present; the one output file is red%03d.png and has transparency.

So there seems to be a valid bug with the indexing and the printf-style output filename, but not with the transparency/opacity.

[Bob Friesenhahn]

The redeclipse.ico file is no longer available via the provided link, but it is likely the same as this one.