The Ubuntu source package for imagemagick does not declare a build dependency on libwebp-dev. Thus imagemagick gets built without webp support. This could be considered a bug in Ubuntu.
Relevant output from the build process:
checking for WEBP...
checking webp/decode.h usability... no
checking webp/decode.h presence... no
checking for webp/decode.h... no
checking for WebPDecodeRGB in -lwebp... no
checking if WEBP package is complete... no
And when libwebp-dev is installed:
checking for WEBP...
checking webp/decode.h usability... yes
checking webp/decode.h presence... yes
checking for webp/decode.h... yes
checking for WebPDecodeRGB in -lwebp... yes
checking if WEBP package is complete... yes
If you want to fix this just for yourself, you can rebuild the package and install your version:
cd /tmp
mkdir imagemagick
cd imagemagick
sudo apt-get build-dep imagemagick
sudo apt-get install libwebp-dev devscripts
apt-get source imagemagick
cd imagemagick-*
debuild -uc -us
sudo dpkg -i ../*magick*.deb
convert -list format
. On my system, with the sameconvert
version, webp doesn't appear.