GraphicsMagick / ImageMagick缺少lib报错no decode delegate for this image format

下载相应的lib，编译安装就行了

cd ~

#下载包
wget http://www.imagemagick.org/download/delegates/zlib-1.2.7.tar.gz
wget http://www.imagemagick.org/download/delegates/libpng-1.6.2.tar.gz
wget ftp://ftp.graphicsmagick.org/pub/GraphicsMagick/delegates/libjpeg-6b.tar.gz
wget http://downloads.sourceforge.net/project/graphicsmagick/graphicsmagick/1.3.18/GraphicsMagick-1.3.18.tar.gz?r=http%3A%2F%2Fsourceforge.net%2Fprojects%2Fgraphicsmagick%2Ffiles%2Fgraphicsmagick%2F1.3.18%2F&ts=1372041452&use_mirror=jaist
tar zvxf zlib-1.2.7.tar.gz
tar zvxf libpng-1.6.2.tar.gz
tar zvxf libjpeg-6b.tar.gz
tar zvxf GraphicsMagick-1.3.18.tar.gz

#安装
cd ~/zlib-1.2.7
./configure
make
make install

cd ~/libjpeg-6b
./configure
make
make install

cd ~/libpng-1.2.49
./configure
make
make install

cd ~/GraphicsMagick-1.3.18
./configure
make
make install

> fs.readdirSync('./upload/')
[ 'c21142262b6e78eeeed5ddbc173efe0d.jpg',
  '3e90077423737f7986a559a355631046.jpg',
  '8a3aee002f1740d3ec4f1eba3d703b8c.jpg',
  'df5f8c5af3311df01d002bbdcdb89925.jpg',
  '5074358977fdcbca7667571f7246004e.jpg',
  '85baa7049a7b87e9b35369a01aae33b9.jpg',
  '62e9071d0b685f32d423e3d74c3eaab1.jpg',
  '65bd0cb519c557fd4f519ae5bef1b97d.jpg' ]
> var jpg = gm('./upload/' + fs.readdirSync('./upload/')[0]);
undefined
> jpg.size(function(){console.log(arguments);});
{ domain: null,
  _events: { size: [Function] },
  _maxListeners: 10,
  _options: {},
  data: {},
  _in: [],
  _out: [],
  _outputFormat: null,
  _subCommand: 'convert',
  source: './upload/c21142262b6e78eeeed5ddbc173efe0d.jpg',
  _sourceFormatters: [ [Function] ],
  bufferStream: false }
> { '0': undefined, '1': { width: 1280, height: 800 } }