rmagick does not overwrite EXIF property

Question

I'm trying to reset the Orientation EXIF field in my image using rmagick 2.13.1 and ruby 1.9.3p194, but it doesn't seem to save.

img = ::Magick::Image::read(local_source_path).first
img.get_exif_by_entry()
=> [["ColorSpace", "1"],
 ["ExifImageLength", "2448"],
 ["ExifImageWidth", "3264"],
 ["ExifOffset", "38"],
 ["Orientation", "6"]]

Orientation can also be acquired thru the properties

img.properties

outputs

{"date:create"=>"2014-01-08T17:26:10-08:00",
 "date:modify"=>"2014-01-08T17:26:05-08:00",
 "exif:ColorSpace"=>"1",
 "exif:ExifImageLength"=>"2448",
 "exif:ExifImageWidth"=>"3264",
 "exif:ExifOffset"=>"38",
 "exif:Orientation"=>"6",
 "jpeg:colorspace"=>"2",
 "jpeg:sampling-factor"=>"2x2,1x1,1x1"}

I try to set Orientation property to nil & save:

img['exif:Orientation'] = nil

Now,

img.properties
=> {"date:create"=>"2014-01-08T17:26:10-08:00",
 "date:modify"=>"2014-01-08T17:26:05-08:00",
 "exif:ColorSpace"=>"1",
 "exif:ExifImageLength"=>"2448",
 "exif:ExifImageWidth"=>"3264",
 "exif:ExifOffset"=>"38",
 "jpeg:colorspace"=>"2",
 "jpeg:sampling-factor"=>"2x2,1x1,1x1"}

which looks correct.

img.write(local_dest_path)

but when I use get_exif_by_entry

img.get_exif_by_entry('Orientation')[0][1]

I still get 6 & not nil.

When I read the written file that was modified local_dest_path, I still get "6".

Is there a set_exif_by_entry function that I'm missing? Any ideas? Thanks

Answer 1

Couldn't set to nil, but I was able to set it to 1 during the write

img.write('local_dest_path') { self.orientation = ::Magick::TopLeftOrientation }

The constant UndefinedOrientation didn't work either. Other values available are listed in OrientationType.