RMagick About RMagick 2
What is RMagick 2?

RMagick 2 is the future of RMagick. This is the version that will get new methods and support new ImageMagick features.

What's new in RMagick 2?

Image objects are big. Most of the memory they use is allocated directly from the operating system and isn't managed by Ruby. RMagick 2 has two new methods to help you manage that memory.

Image#destroy!
This method returns all the unmanaged memory used by an image to the system, making it available for reuse. After an image is destroyed, if you try to call any method (except #inspect and the new #destroyed? method), RMagick raises a DestroyedImageError exception. You no longer have to call GC.start to forcibly clean up unused images.
Magick.trace_proc=
This attribute helps you keep track of the images being used by your program. trace_proc accepts a Proc value which is called each time an image is created or destroyed. The proc gets a unique identifier for the image and a string that describes the image. If the image originated from a file, the description includes the filename.

Other new features:

Prerequisites

RMagick 2 does not support GraphicsMagick.

Installation

If you're installing RMagick 2 on Windows, use the RMagick 2.0.0 binary gem for Ruby 1.8.6. This gem is bundled with a a copy of the ImageMagick Windows installer so you don't need to download your own copy. Download the gem from the rmagick-win32 project on RubyForge, unzip it into a temporary directory, and follow the instructions in the README.html file you'll find in the package.

On Linux, BSD, OS X, and other systems, the process for installing RMagick 2 with RubyGems is identical to the process for installing RMagick 1. See the installation FAQ for your system.

If you've installed RMagick 1 in the past using a tarball, note that RMagick 2 is installed with Minero Aoki's setup.rb command. Install ImageMagick normally (see the installation FAQ for your system), download and untar the RMagick 2 tarball, change to the RMagick 2 directory, and enter

ruby setup.rb
sudo ruby setup.rb install

to install RMagick. You can read more about this procedure in the README.html file.

Documentation

As always, installing RMagick 2 also installs a complete copy of the The RMagick User's Guide and Reference. The doc is also available online here.

FAQ
How should I decide between RMagick 1 and RMagick 2?
Choose RMagick 2 if
  1. You want to test your programs with Ruby 1.9.
  2. You want to use functionality that has been added in ImageMagick 6.3.0 and later.
  3. You want to have more control over RMagick's memory usage.
Choose RMagick 1 if
  1. You want to use a release of Ruby prior to 1.8.2 or ImageMagick prior to 6.3.0.
  2. You want to use RMagick with GraphicsMagick.
  3. You have existing scripts that use methods that have been removed from RMagick 2.
Can I use my existing RMagick scripts with RMagick 2?
Almost certainly. RMagick 2 removes support for a handful of rarely-used and long-deprecated methods such as Image#grayscale_pseudo_class and Image#statistics. Usually these methods have been replaced by methods that are supported. For a complete list of methods that have been removed in RMagick 2 see the ChangeLog.
What's going to happen to RMagick 1?
Nothing. I still support RMagick 1 and will fix bugs as they are reported. As of this writing I've produced 12 update releases. If some change to ImageMagick breaks RMagick, I'll do my best to fix it, just like I always have. However, changes to RMagick will be limited to bug fixes. I don't plan to add any new functionality.
Will RMagick 1 ever support Ruby 1.9?
No.
Do you plan to add support for GraphicsMagick to RMagick 2?
No.
Why did you change the prerequisites?
RMagick 1 supports ImageMagick 6.0.0 (released in April, 2004) through the current release, GraphicsMagick 1.0.0 (released in May, 2003) through the current release, and Ruby 1.6.7 (released in March, 2003) through Ruby 1.8.6. The work of supporting so many releases has become more than I want to handle, so I decided to focus my efforts on newer and more widely-used releases of Ruby and ImageMagick.