[KimDaBa] rotation bug..

jedd jedd at progsoc.org
Mon Nov 29 22:17:06 GMT 2004

On Tue, 30 Nov 2004 09:50 am, Gael Beaudoin wrote:
 ] I dunno. This is why I said I dunno how you could handle this.
 ] When a photo is rotated, its checksum has changed ?

 The thing is that many other operations can change the checksum,
 and while it's a trivial task to compare two photos to see if one is a
 rotation (geometrical transformation?) of the other .. and when I say
 trivial, I mean in comparison to writing a panorama plugin :) .. it's
 a non-trivial task to do this comparison when you've only got one
 of the files available, and a 10-byte-ish checksum that represents the
 other 3mb file.

 But it's a good question .. and one without an easy answer.

 If you're always going to use KimDaBa to view .. then it's easy - you
 just let it manage the rotations according to your changes when you
 log files into the system.

 If you ever want to access the files thru other packages .. then it's
 probably sage advice to manually go thru and fix up the rotations
 outside of KimDaBa, before you log them into KimDaBa that is.

 The trick *there* is to make sure you use an app that doesn't a) mung
 the EXIF data, and/or b) decode, rotate, and then re-encode - you'd
 stand to lose much quality.

 ImageMagick's convert utility - with the -rotate command - seems to
 retain EXIF & quality aspects of the original photo.  And it's fast and
 easy to wrap scripts around.

 Certainly this is another of those tricky things that you need to know
 about before you import thousands of photos .. but that you won't know
 you need to know about until after you've done exactly that.

 Welcome to IT.  :)


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