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How to apply shadow to thumbnails using imagemagick and paperclip?

I would like to change the processing of thumbnails in a folder using imagemagick to apply a shadow to all thumbnails. What I'm stuck with is a real imagemagick team that would pull out this little miracle. Everything I tried returns an incorrectly scaled shadow without the original image.

def transformation_command scale, crop = @current_geometry.transformation_to(@target_geometry, crop?) trans = "" trans << " -resize \"#{scale}\"" trans << " -crop \"#{crop}\" +repage" if crop # Apply Drop Shadow trans << " #{convert_options}" if convert_options? trans end

I tried one ...

 def transformation_command scale, crop = @current_geometry.transformation_to(@target_geometry, crop?) trans = "" trans << " -resize \"#{scale}\"" trans << " -crop \"#{crop}\" +repage" if crop trans << " \( +clone -background black -shadow 60x5+10+10 \) +swap -background none -layers merge +repage" trans << " #{convert_options}" if convert_options? trans end

I am completely new to imagemagick, any help would be greatly appreciated.

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After some trial and error and burying my head in the documents, I finally realized this.

 has_attached_file :image, :styles => { :thumb => ["100x100#", :png] }, :convert_options => { :thumb => '\( +clone -background black -shadow 70x4+0+0 \) +swap -background none -layers merge +repage' }
  • Make sure the latest version of ImageMagick is installed.
  • ["100x100 #" ,: png] converts the image to png so that the shadow is transparent.
  • In the conversion options: thumb applies only to conversion to style: thumb, use: all to apply the conversion to all your styles.
  • Adjust "70x4 + 0 + 0" to get the desired shadow.
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It’s much easier for me to just use the rmagick interface rather than send command line options to imagine myself.

If you use rmagick, you can use the shadow method.

 img = Image.read('slide.png').first shadow = img.shadow(0, 0, 0.0, '20%')

and then compose the image on top of the shadow.

I wrote an article about using rmagick: http://schf.uc.org/articles/2006/10/18/render-greatlooking-collages-with-ruby-and-rmagick

Try reading it, it may give you a better understanding.

I also wrote a lib abstraction for rmagick that tries to make it even easier to use. I called it RubyShop because it tried to simulate a Photoshop-based layer layout .. (I really hate the name and will probably change it if I ever resurrect the project)

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