Editing GraphicsMagick
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Octave will use [http://www.graphicsmagick.org/ GraphicsMagick] for reading and writing your images (not | Octave will use [http://www.graphicsmagick.org/ GraphicsMagick] for reading and writing your images (not plots, only if you are actually doing image processing). This means that the GraphicsMagick configuration you have on you system will limit what your Octave installation can do. Most systems will have it onn their repositories. Unfortunately, their configuration is not always the best for image analysis as it limits reading of images to 8-bit. | ||
== Quantum depth == | == Quantum depth == | ||
The most common problem is the following warning when using {{Codeline|imread()}} | The most common problem is the following warning when using {{Codeline|imread()}}: | ||
<pre>warning: your version of GraphicsMagick limits images to 8 bits per pixel</pre> | <pre>warning: your version of GraphicsMagick limits images to 8 bits per pixel</pre> | ||
The reason for this is that GraphicsMagick was compiled with {{Codeline|--with-quantum-depth 8}}. Possible values are 8, 16 or 32, each implememnting that limitation. See the {{Path|INSTALL}} [http://graphicsmagick.hg.sourceforge.net/hgweb/graphicsmagick/graphicsmagick/file/tip/INSTALL-unix.txt#l429 file] on GraphicsMagick sourcefor an explanantion of this. There has bugs reported requesting package maintainers to compile it with higher values. You should not create a new bug, instead leave a comment on the already open bugs: [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=557879 Debian], [https://bugs.launchpad.net/ubuntu/+source/graphicsmagick/+bug/696215 Ubuntu]. | |||
There | |||
As versions with higher values are not available on the repositories, the solution is to compile it. Octave needs then to be recompiled to use the freshly compiled Magick++ library. | |||
== Magick++ == | == Magick++ == | ||
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== Dependencies == | == Dependencies == | ||
Compiling from source means tracking the dependencies yourself which may be a kind of painful. There's no wiki for GraphicsMagick so the following table hopes to makes things easier | Compiling from source means tracking the dependencies yourself which may be a kind of painful. There's no wiki for GraphicsMagick so the following table hopes to makes things easier: | ||
{| class="wikitable" | {| class="wikitable" | ||
|- | |- | ||
! | ! Distro !! Debian !! Ubuntu | ||
|- | |- | ||
| | | liblzma || liblzma-dev || liblzma-dev | ||
|- | |- | ||
| | | libtiff || libtiff5-dev || libtiff5-dev | ||
|- | |- | ||
| | | libwmf || libwmf-dev || libwmf-dev | ||
|- | |- | ||
| | | libxml2 || libxml2-dev || libxml2-dev | ||
|- | |- | ||
| zlib || zlib1g-dev || zlib1g-dev | |||
|} | |} |