Is there a simple way to get image dimensions in Ruby?

Question

I\'m looking for an easy way to get width and height dimensions for image files in Ruby without having to use ImageMagick or ImageScience (running Snow Leapard).

Answer 1

There's also a new (July 2011) library that wasn't around at the time the question was originally asked: the Dimensions rubygem (which seems to be authored by the same Sam Stephenson responsible for the byte-manipulation techniques also suggested here.)

Below code sample from project's README

require 'dimensions'

Dimensions.dimensions("upload_bird.jpg")  # => [300, 225]
Dimensions.width("upload_bird.jpg")       # => 300
Dimensions.height("upload_bird.jpg")      # => 225

Answer 2

As of June 2012, FastImage which "finds the size or type of an image given its uri by fetching as little as needed" is a good option. It works with local images and those on remote servers.

An IRB example from the readme:

require 'fastimage'

FastImage.size("http://stephensykes.com/images/ss.com_x.gif")
=> [266, 56]  # width, height

Standard array assignment in a script:

require 'fastimage'

size_array = FastImage.size("http://stephensykes.com/images/ss.com_x.gif")

puts "Width: #{size_array[0]}"
puts "Height: #{size_array[1]}"

Or, using multiple assignment in a script:

require 'fastimage'

width, height = FastImage.size("http://stephensykes.com/images/ss.com_x.gif")

puts "Width: #{width}"
puts "Height: #{height}"