I'm getting an error message "Fatal error: Call to a member function getTiff() on a non-object in..." when I try to edit a description (taken from an example in the documentation) of an image processed with GD.
It works fine though on images that come straight from the camera and that have not been processed with GD.
Unlike IPTC, EXIF was (still is?) a write-once-read-only-format. There is a class (#1042) in PHPclasses for EXIF modification but I've not seen anyone say that it works.
FWIW: Here's a note from php.net GD Manual comments dated Dec 2008.
You know, maybe this goes without saying, but I thought I would drop a note in here. When developing code to resize images, it is best not to use GD. When using the current GD methodologies, you are reading content from an image and manipulating it. By then writing that content to a brand new file, you are losing the EXIF data.
For purposes when you want to retain EXIF data, it is recommended that you compile in and use the PECL Imagick extension. It has great resizing methods built right in and the EXIF data is retained.
unfortunately, I cannot use the PECL Imagick extension because it breaks dcf compatibility
the whole reason why I use GD is because it keeps the images dcf compatible. everything else I've tried to far for resizing photos will result in an error on my digital camera when I place them back on the camera
EXIF is definitely not read only. I have been able to edit EXIF data. I just have this problem with editing it after using GD to resize the photo.
Msg#: 4112836 posted 12:21 am on Apr 13, 2010 (gmt 0)
My experience has been primarily with IPTC data but from what I'm seeing out there, PEL seems to be the only option with GD.
Part of the reason for the lack of apps may be that EXIF is apparently a standard in flux. As I understand it, the EXIF standard was originally set up as read-only. Some apps, like MS Expression Media, choose to follow the standard. Geo-tagging, in particular, has called for work-arounds.
"EXIF data is typically considered read-only. Fortunately, the Annotations section geocoding fields have been extended to include Latitude and Longitude. This allows you to correct or add GPS locations to your existing photos."