How to retrieve EXIF information of an image in Rails

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).Can any one help me out???

Thanks!!!

There are 3 gems to do this:

1. [mini_exiftool](

[To see links please register here]

): ExifTool command-line wrapper
2. [exifr](

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): Pure Ruby
3. [exif](

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): 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.

after_photo_post_process :copy_exif_data
private
def copy_exif_data
exif =EXIFR::JPEG.new(photo.queued_for_write[:original])
self.exif_value = exif
end


This is working code which i am used.

You might try the [mini_exiftool](

[To see links please register here]

) gem, a wrapper for the [exiftool](

[To see links please register here]

) 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](

[To see links please register here]

). It also supports reading *and* writing of exif data, whereas exifr only supports reading.

Did you give [exifr](

[To see links please register here]

) gem a try? From the documentation

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