How to retrieve EXIF information of an image in Rails

Did you give exifr gem a try? From the documentation

EXIFR::JPEG.new('IMG_6841.JPG').width               # => 2272EXIFR::JPEG.new('IMG_6841.JPG').height              # => 1704EXIFR::JPEG.new('IMG_6841.JPG').exif?               # => trueEXIFR::JPEG.new('IMG_6841.JPG').model               # => "Canon PowerShot G3"EXIFR::JPEG.new('IMG_6841.JPG').date_time           # => Fri Feb 09 16:48:54 +0100 2007EXIFR::JPEG.new('IMG_6841.JPG').exposure_time.to_s  # => "1/15"EXIFR::JPEG.new('IMG_6841.JPG').f_number.to_f       # => 2.0

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 = 50FILE_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 }  endend

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        realmini_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.

You might try the mini_exiftool gem, a wrapper for the exiftool command-line tool.

While the gem requires you to actually install the command-line tool, the result is that you get a lot more power. Compared to exifr, which only gives you support for JPG and TIF files, exiftool supports a huge number of file formats. It also supports reading and writing of exif data, whereas exifr only supports reading.