the imagemagick man pages (like man convert) suggest to read the html documentation at (for example) file:///usr/share/doc/imagemagick-6.2.6.0/www/convert.html while the actual documentation is installed to file:///usr/share/doc/imagemagick-6.2.6.0/html/www/convert.html
fixed in imagemagick-6.2.9.5
This seems to be an issue with currently available versions of imagemagick as well. Any chance this bug can be reopened? (media-gfx/imagemagick-7.0.9.22 here. This time it lacks the html/ subdirectory and mentions a non-existing directory under /usr/share/docs (ImageMagick-7 instead of imagemagick-7.0.9.22).)