ImageMagick is a freely available open-source image processing library and set of applications capable of performing conversion, manipulation and drawing in almost 100 different formats. It can run on Unix-like operating systems such as Linux and Mac OS as well as Windows.
CollectiveAccess can use ImageMagick to convert uploaded images to web-viewable formats such as JPEG, PNG and TilePic.
CollectiveAccess can access ImageMagick functionality in in one of two ways:
- By executing the ImageMagick command-line utilities directly. For this to work you will have to make sure that the directory path to the location of your ImageMagick executables as configured in [ExternalApplicationsConfiguration external_applications.conf] is correct.
- Using PHP function calls defined by the PECL IMagick PHP extension. This is the best performing method of access and is generally supported by Linux distributions. Note that IMagick can be unstable when processing certain malformed, or otherwise "odd", image files. An IMagick crash will bring down the entire Apache request resulting in a dreaded "white screen" (blank screen with no error message). If you are seeing white screens when uploading image media with IMagick enabled, try setting the dont_use_imagick directive in the app.conf configuration file. This will disable IMagick support and fall back to the command-line ImageMagick approach.
If IMagick is not present on your system, CA will automatically fall back to using the ImageMagick command-line utilities. If ImageMagick is not present at all on your system, or the ImageMagick path in external_applications.conf is incorrectly configured, then the GD image processing library will be used.
Note: the default paths in external_applications.conf point to /usr/local/bin while on debian linux, and debian derivatives such as Ubuntu, these items are in /usr/bin . If you know that you have a tool like imagemagick or ghostscript installed yet the Admin ConfigurationCheck page is reporting that they are not enabled because they are missing, edit the paths in the external_application.conf file.
You can learn more about !ImageMagick at http://www.imagemagick.org