2017-03-18 15:27 GMT+01:00 Andreas Politz <politza@hochschule-trier.de>:

Fabrice Popineau <fabrice.popineau@gmail.com> writes:

> Maybe a stupid question but if emacs is compiled with ImageMagick support,
> what is the point in asking JPEG, PNG, etc support at the same time from independent libraries ?
> Shouldn't configure made those options to be exclusive ?

Imagemagick is handled like an image type, so png and imagemagick are
two different types. One uses libpng as backend and the other
libmagick.

My point is that only one of imagemagick and libpng will handle png files at a time.

When ImageMagick is available, it supersedes png, jpeg and anything it handles (AFAICS).

If you want to let libpng handle png files, you need to change some defaults

(imagemagick-filter-types, etc.)

> Also what is (are) the drawback(s) of ImageMagick support vs the other libraries ?

In my experience, libpng is faster then imagemagick.

Ok, that is understandable.

Fabrice