Re: [gthumb-list] Bug: EXIF orientation is broken after resize

[damien clochard <damien dalibo info>]

Le 02/02/2013 04:36, Rennie deGraaf a écrit :
> On 01/02/13 12:54 PM, damien clochard wrote:
> > Le 29/01/2013 16:30, Dr. Michael J. Chudobiak a écrit :
> > > > > the orientation field makes sense only in the original image, when you
> > > > > create a new image it is better to reset it.
> > > >
> > > > Sorry again but I don't understand this logic. I don't see how resetting
> > > > the orientation after a resize operation is useful to anyone. These are
> > > > two different things. My understanding is that gthumb should keep this
> > > > orientation when user ask for a resize.
> > > >
> > > > Am I correct ?
> > >
> > > No. The orientation tag is taken into account when the image is loaded
> > > into memory.
> > >
> > > The resize happens on the image in memory.
> >
> > Yes I am aware that the transformation are executed "in memory" and not
> > directly on disk :-) Anyway I don't see how this is related with the
> > issue I described.
>
> As I understand it (forgive me if this has changed since I last looked
> at the code), gThumb rotates every image that it loads to the "top-left"
> orientation.  If it subsequently saves the image, it uses the rotated
> image data and sets the EXIF tag to "top-left" to ensure that the tag
> matches the data.

Ok thanks for your explanations. I understand now that my problem has
nothing to do with the resize operation. I still think that The Gimp has
a better approach for this rotate-or-keep-exif-tag issue but that's not
the subject here. Anyway let's close this discussion, and go back to my
initial problem.

The scenario is even simpler now :

1/ Open this file : http://nawak.taadeem.net/DSC_1114.orig.JPG
2/ Save it as DSC_1114.png

The original photo is in portrait format.

The NIKON file has the following tags :

  X Dimension : 2896
  Y Dimension : 1944
  Orientation : left, bottom

When Gthumb displays the picture as a thumbnail it's in portrait format.
When the picture is in full screen mode is displayed in landscape.

The PNG file has the following tags :

  X Dimension : 2896
  Y Dimension : 1944
  Orientation : top, left

see http://nawak.taadeem.net/DSC_1114.png

I used gThumb 3.1.3