Fix support for imagemagick <3.3, refs #7762
Fix support for imagemagick <3.3, refs #7762

staabm/composer,naderman/composer,composer/composer,fabpot/composer,johnstevenson/composer,nicolas-grekas/composer,slbmeh/composer,localheinz/composer,alcohol/composer,andrerom/composer,floverdevel/composer,stof/composer,pierredup/composer,stefangr/composer,milleruk/composer