image_size

Measure image size/dimensions using pure Ruby. Formats: apng, avif, bmp, cur, emf, gif, heic, heif, ico, j2c, jp2, jpeg, jpx, mng, pam, pbm, pcx, pgm, png, ppm, psd, svg, swf, tiff, webp, xbm, xpm.

Installation

gem install image_size

Bundler

Add to your Gemfile:

gem 'image_size', '~> 3.0'

Usage

image_size = ImageSize.path('spec/images/jpeg/436x429.jpeg')

image_size.format       #=> :jpeg
image_size.width        #=> 436
image_size.height       #=> 429
image_size.w            #=> 436
image_size.h            #=> 429
image_size.size         #=> [436, 429]
image_size.size.to_s    #=> "436x429"
"#{image_size.size}"    #=> "436x429"
image_size.size.width   #=> 436
image_size.size.height  #=> 429
image_size.size.w       #=> 436
image_size.size.h       #=> 429
image_size.media_type   #=> "image/jpeg"
image_size.media_types  #=> ["image/jpeg"]
image_size.byte_size    #=> 10938

Or using IO object:

image_size = File.open('spec/images/jpeg/436x429.jpeg', 'rb'){ |fh| ImageSize.new(fh) }

Any object responding to read and eof?:

require 'image_size'

image_size = ImageSize.new(ARGF)

Works with open-uri, see experimental HTTP server interface below:

require 'image_size'
require 'open-uri'

image_size = URI.parse('http://www.rubycgi.org/image/ruby_gtk_book_title.jpg').open('rb') do |fh|
  ImageSize.new(fh)
end

image_size = open('http://www.rubycgi.org/image/ruby_gtk_book_title.jpg', 'rb') do |fh|
  ImageSize.new(fh)
end

Note that starting with version 2.0.0 the object given to ImageSize will not be rewound before or after use. So rewind if needed before passing to ImageSize and/or rewind after passing to ImageSize before reading data.

require 'image_size'

File.open('spec/images/jpeg/436x429.jpeg', 'rb') do |fh|
  image_size = ImageSize.new(fh)

  fh.rewind
  data = fh.read
end

File.open('spec/images/jpeg/436x429.jpeg', 'rb') do |fh|
  data = fh.read
  fh.rewind

  image_size = ImageSize.new(fh)
end

Configuration

DPI used for converting svg and emf dimensions can be configured from default 72:

ImageSize.dpi = 150

Chunk size used for reading files, IO and from remote can be configured from default 4096:

ImageSize.chunk_size = 256

Experimental: fetch image meta from HTTP server

If server recognises Range header, only needed chunks will be fetched even for TIFF images, otherwise required amount of data will be fetched, in most cases first few kilobytes (TIFF images is an exception).

require 'image_size/uri'

url = 'http://upload.wikimedia.org/wikipedia/commons/b/b4/Mardin_1350660_1350692_33_images.jpg'
p ImageSize.url(url).size

This interface is as fast as dedicated gem fastimage for images with meta information in the header:

url = 'http://upload.wikimedia.org/wikipedia/commons/b/b4/Mardin_1350660_1350692_33_images.jpg'
puts Benchmark.measure{ p FastImage.size(url) }

[9545, 6623]
  0.004176   0.001974   0.006150 (  0.282889)

puts Benchmark.measure{ p ImageSize.url(url).size }

[9545, 6623]
  0.005604   0.001406   0.007010 (  0.238629)

And considerably faster for images with meta information at the end of file:

url = "https://upload.wikimedia.org/wikipedia/commons/c/c7/Curiosity%27s_Vehicle_System_Test_Bed_%28VSTB%29_Rover_%28PIA15876%29.tif"
puts Benchmark.measure{ p FastImage.size(url) }

[7360, 4912]
  0.331284   0.247295   0.578579 (  6.027051)

puts Benchmark.measure{ p ImageSize.url(url).size }

[7360, 4912]
  0.006247   0.001045   0.007292 (  0.197631)

Configuration

Maximum number of redirects can be configured from default 5:

ImageSize.max_redirects = 10

Or redirects can be disabled:

ImageSize.max_redirects = 0

A url checker can be added to reduce SSRF risk:

ImageSize.uri_checker = lambda do |uri|
  raise 'host is not allowed' unless uri.host == 'upload.wikipedia.org'
end

Alternatively private_address_check gem can be of help:

require "private_address_check/tcpsocket_ext"

PrivateAddressCheck.only_public_connections do
  ImageSize.url(url).size
end

Licence

This code is free to use under the terms of the Ruby's licence.

Original author: Keisuke Minami keisuke@rccn.com.\ Further development 2010-2026 Ivan Kuchin https://github.com/toy/image_size