See
http://www.imagemagick.org/script/license.php. The license in simple terms:
It allows you to:
* freely download and use ImageMagick software, in whole or in part, for personal, company internal, or commercial purposes;
* use ImageMagick software in packages or distributions that you create.
It forbids you to:
* redistribute any piece of ImageMagick-originated software without proper attribution;
* use any marks owned by ImageMagick Studio LLC in any way that might state or imply that ImageMagick Studio LLC endorses your distribution;
* use any marks owned by ImageMagick Studio LLC in any way that might state or imply that you created the ImageMagick software in question.
It requires you to:
* include a copy of the license in any redistribution you may make that includes ImageMagick software;
* provide clear attribution to ImageMagick Studio LLC for any distributions that include ImageMagick software.
It does not require you to:
* include the source of the ImageMagick software itself, or of any modifications you may have made to it, in any redistribution you may assemble that includes it;
* submit changes that you make to the software back to the ImageMagick Studio LLC (though such feedback is encouraged).
A few other clarifications include:
* ImageMagick is freely available without charge;
* you may include ImageMagick on a DVD as long as you comply with the terms of the license;
* you can give modified code away for free or sell it under the terms of the ImageMagick license or distribute the result under a different license, but you need to acknowledge the use of the ImageMagick software;
* the license is compatible with the GPL.