Arch Linux

supercow

Member

Registered: 2010-02-05

Posts: 58

[solved] Image orientation issue

Hello,

I have a problem with image orientation.
I am using Arch64 and KDE 4.4.5 from Arch.

When I look at my pictures in digikam (1.3.0) or gwenview, portrait pictures are displayed fine. If I send them with thunderbird, portrait images are displayed with landscape orientation.

The only workaround I found is to rotate twice the image with digikam (once on the right and once on the left to set it back to previous orientation).

I have noticed that EXIF information change...does anyone have the same issue and knows what is the cause of it ?

before, orientation is "droit, haut" = "right, top"

after, orientation is "haut, gauche" = "top, left" and width and heigth size is set...

regards

Last edited by supercow (2010-07-08 17:20:11)

hbekel

Member

Registered: 2008-10-04

Posts: 311

Re: [solved] Image orientation issue

Digital cameras create images that aren't rotated as such -- as plain images they're always in landscape format. If your camera has an orientation sensor, it will merely hint at the intended orientation by setting the exif orientation value in the jpeg file (instead of really rotating the image and creating a jpeg with a portrait format).

Not all programs interpret all exif data. Programs that don't interpret the exif orientation (as thunderbird seems to do it) will display the image as it is (always in landscape), while others (like digikam) use the exif data to decide on how to rotate the image for display. So digikam is just smart enough to show the image in it's "logical" portrait format while it's "physically" remains in landscape format.

To make a real portrait jpeg, you have to really rotate it and adjust the exif orientation accordingly, which is what effectively happens if you use digikam in the way you describe it. So that's not a workaround, but required to make sure that all programs display the images in the desired format, and not just those that are smart enough to honor the exif orientation.

See the jpegexiforient and jpegautotran programs for an explanation and an alternative way to rotate images based on their exif orientation value.

Last edited by hbekel (2010-07-07 21:55:00)

supercow

Member

Registered: 2010-02-05

Posts: 58

Re: [solved] Image orientation issue

thanks a lot for your explanation

regards
Olivier