MiniMagick

A ruby wrapper for ImageMagick or GraphicsMagick command line.

Tested on the following Rubies: MRI 1.9.2, 1.9.3, 2.0.0, 2.1.1, JRuby, Rubinius.

Installation

Add the gem to your Gemfile:

gem "mini_magick"

Information

• Rdoc

Why?

I was using RMagick and loving it, but it was eating up huge amounts of memory. Even a simple script would use over 100MB of Ram. On my local machine this wasn't a problem, but on my hosting server the ruby apps would crash because of their 100MB memory limit.

Solution!

Using MiniMagick the ruby processes memory remains small (it spawns ImageMagick's command line program mogrify which takes up some memory as well, but is much smaller compared to RMagick)

MiniMagick gives you access to all the command line options ImageMagick has (Found here http://www.imagemagick.org/script/mogrify.php)

Examples

Want to make a thumbnail from a file...

image = MiniMagick::Image.open("input.jpg")
image.resize "100x100"
image.write  "output.jpg"

Want to make a thumbnail from a blob...

image = MiniMagick::Image.read(blob)
image.resize "100x100"
image.write  "output.jpg"

Got an incoming IOStream?

image = MiniMagick::Image.read(stream)

Want to make a thumbnail of a remote image?

image = MiniMagick::Image.open("http://www.google.com/images/logos/logo.png")
image.resize "5x5"
image.format "gif"
image.write "localcopy.gif"

Need to combine several options?

image = MiniMagick::Image.open("input.jpg")
image.combine_options do |c|
  c.sample "50%"
  c.rotate "-90>"
end
image.write "output.jpg"

Want to composite two images? Super easy! (Aka, put a watermark on!)

image = Image.open("original.png")
result = image.composite(Image.open("watermark.png", "jpg")) do |c|
  c.gravity "center"
end
result.write "my_output_file.jpg"

Want to manipulate an image at its source (You won't have to write it out because the transformations are done on that file)

image = MiniMagick::Image.new("input.jpg")
image.resize "100x100"

Want to get some meta-information out?

image = MiniMagick::Image.open("input.jpg")
image[:width]               # will get the width (you can also use :height and :format)
image["EXIF:BitsPerSample"] # It also can get all the EXIF tags
image["%m:%f %wx%h"]        # Or you can use one of the many options of the format command

For more on the format command see http://www.imagemagick.org/script/command-line-options.php#format

Want to composite (merge) two images?

first_image = MiniMagick::Image.open "first.jpg"
second_image = MiniMagick::Image.open "second.jpg"
result = first_image.composite(second_image) do |c|
  c.compose "Over" # OverCompositeOp
  c.geometry "+20+20" # copy second_image onto first_image from (20, 20)
end
result.write "output.jpg"

Thinking of switching from RMagick?

Unlike RMagick, MiniMagick is a much thinner wrapper around ImageMagick.

• To piece together MiniMagick commands refer to the Mogrify Documentation. For instance you can use the -flop option as image.flop.
• Operations on a MiniMagick image tend to happen in-place as image.trim, whereas RMagick has both copying and in-place methods like image.trim and image.trim!.
• To open files with MiniMagick you use MiniMagick::Image.open as you would Magick::Image.read. To open a file and directly edit it, use MiniMagick::Image.new.

Windows Users

When passing in a blob or IOStream, Windows users need to make sure they read the file in as binary.

# This way works on Windows
buffer = StringIO.new(File.open(IMAGE_PATH,"rb") { |f| f.read })
MiniMagick::Image.read(buffer)

# You may run into problems doing it this way
buffer = StringIO.new(File.read(IMAGE_PATH))

Using GraphicsMagick

Simply set

MiniMagick.processor = :gm

And you are sorted.

Optional image validation

By default, MiniMagick validates image each time it's opening or writing it. Validation means executing identify -quiet -ping command on target image. This adds additional overhead to the whole processing. Sometimes it's safe to assume that all input and output images are valid by default and turn off validation:

MiniMagick.validate_on_create = false
MiniMagick.validate_on_write = false

Requirements

You must have ImageMagick or GraphicsMagick installed.

Caveats

Version 3.5 doesn't work in Ruby 1.9.2-p180. If you are running this Ruby version use the 3.4 version of this gem.