I am trying to install RMagick on my slicehost(Linux Hardy) instead of compile from source, here is what I did:
$ sudo aptitude install -y imagemagick
$ sudo aptitude install -y libmagick9-dev
$ sudo gem install rmagick
After installed, it reads GIF with no problem, however for JPEG and PNG, I keep getting this error:
Magick::ImageMagickError: no decode delegate for this image format
I know it is probably because I don't have libpng and libjpg libraries, but i didn't find guide on how to install these. I compiled libpng and libjpg from source, with no luck, the files are in the /usr/lib, but i still getting the error.