Confusion over non-Exif orientation data

Questions and postings pertaining to the development of ImageMagick, feature enhancements, and ImageMagick internals. ImageMagick source code and algorithms are discussed here. Usage questions which are too arcane for the normal user list should also be posted here.
Post Reply
pneuman
Posts: 4
Joined: 2013-07-17T17:21:14-07:00
Authentication code: 6789

Confusion over non-Exif orientation data

Post by pneuman »

Hi,

I have a JPEG that has orientation data in it, but it's not in the EXIF data -- it's stored, AFAICT, in an XMP-tiff metadata field. When I query the file for its orientation, using "identify -format '%[EXIF:Orientation]'", it reports nothing. However, when I convert the image using "-auto-orient", it does rotate the image. The documentation for -auto-orient says that it looks at EXIF data:

http://www.imagemagick.org/script/comma ... uto-orient

but it does seem to find and act upon the orientation stored in the file, even though it's not in the EXIF data. That does seem like the right thing to do, but it's not consistent with the documentation.

In this thread on the users forum ( viewtopic.php?f=1&t=23777&p=101043#p100897 ) we discovered that using the format string "%[Orientation]" instead of "%[EXIF:Orientation]" will extract the orientation from this file, but will this orientation always be consistent with the orientation used to control the behaviour of -auto-orient?

The image in question is here: http://wootangent.net/~lsd/blah/0000221676_0.jpg

Thanks!
Post Reply