How to retrieve EXIF information of an image in Rails

Question

I am using Rails paperclip for displaying the images in my page. I want to know how to retrieve EXIF information of an image(like dimensions, camera model,height,width., etc).Ca

Answer 1

There are 3 gems to do this:

1. mini_exiftool: ExifTool command-line wrapper
2. exifr: Pure Ruby
3. exif: C Extension (by me)

If you want to write or edit EXIF tag, you should choose mini_exiftool, it's more powerful but very slow, as the benchmark shown below, exif is 8 times faster than exifr, and 1200 times than that of mini_exiftool.

benchmark:

require 'benchmark'
require 'mini_exiftool'
require 'exifr'
require 'exif'

N = 50
FILE_PATH = File.expand_path('../../spec/sample.jpg', __FILE__)
Benchmark.bmbm do |x|
  x.report 'mini_exiftool' do
    N.times{ MiniExiftool.new(FILE_PATH).image_width }
  end
  x.report 'exifr' do
    N.times{ EXIFR::JPEG.new(FILE_PATH).width }
  end
  x.report 'exif' do
    N.times{ Exif::Data.new(FILE_PATH).image_width }
  end
end

output:

Rehearsal -------------------------------------------------
mini_exiftool   0.150000   0.050000  12.390000 ( 12.546417)
exifr           0.090000   0.000000   0.090000 (  0.091090)
exif            0.010000   0.000000   0.010000 (  0.010343)
--------------------------------------- total: 12.490000sec
                    user     system      total        real
mini_exiftool   0.150000   0.050000  12.400000 ( 12.540122)
exifr           0.080000   0.000000   0.080000 (  0.083251)
exif            0.010000   0.000000   0.010000 (  0.009855)

mini_exiftool is a bit overkill to only retrieve data. So in your case, I think you should use exifr in JRuby, or give exif a try in MRI.