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Be aware of an iMovieHD/iPhoto image rotation glitch
Authored by: Anonymous on Oct 26, '05 07:55:24AM

There is a logic behind this behaviour. When you only rotate a picture using iphoto, the program adds this info to the EXIF comments instead of altering and resaving the file, as this would result in jpeg degradation. When other EXIF capable program opens the file (as preview.app) it interprets the info and rotates the picture acordingly.

Obviously iMovie HD does not interpret EXIF comments.

The solution provided of lightly altering the picture forces iPhoto to resave the picture, which it does including the rotation of the picture as it has to alter the image anyway. Note that this will degrade the quality of the picture although if only done once or twice it will be hardly noticeable.

A similar behaviour is encountered when rotating a jpeg with preview and then trying to open it with safari. Some would argue this is a bug as in some circumstances it doesn't behave as expected. I would rather say that it is a lack of features in some applications (which in itself is not a bug) although for the sake of integration apple should have included it in all their products. If such features are esential to the normal functioning of these apps or not is a discussion that IMHO is beyond this post.

I haven't tested if this behaviour applies only to .jpeg images or if it also is reproduced on lossles formats like .tiff.



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Be aware of an iMovieHD/iPhoto image rotation glitch
Authored by: gleavell on Nov 27, '05 06:55:47PM

This makes sense, but it's not happening that way for me. I'm using iPhoto 5.0.4 (398) in Tiger, and selecting "Rotate" really changes the image file and leaves the EXIF orientation field alone.

On the other hand, if I rotate an image with Preview 3.0.3 (398), the image remains untouched and the orientation field is changed.

What I find really interesting is iPhoto's handling of images during import. If the image's orientation field indicates that the image has been rotated, iPhoto will silently perform a real rotation on the image and reset the orientation field. And, as it does when you perform any modication to an original image, it even stores a copy of the pre-iphoto-rotated image in the "Originals" subdirectory underneath the hood of the iPhoto Library directory structure. In fact, "revert to original" is avalable so that you can bring the image back to it's original state. If you *do* revert to original, iPhoto then honors the original EXIF orientation flag and continues to display the "rotated" image. At least that's how it's working for me today.

Does anyone know if iPhoto's rotation is lossless?

With regard to what other OS X utilities honor the orientation field, I've noticed this so far:

*Does* honor EXIF orientation field:
- Preview
- Finder column view preview

Does *not* honor EXIF orientation field:
- Safari 2.0.2 (416.12) (Neither does Firefox 1.5RC3)
- iPhoto File / Add to Library browse window preview
- Desktop background

Glenn



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