[Digikam-users] Lossless rotation is lossy!

[Marcel Wiesweg]

> > For me lossless qualifies as lossless if you rotate forth and rotate back 
> > and 
> > the resulting file, at least the pixel data, is identical to the original 
> > unrotated form

> Same for me. But that is the point, Digikam (at least my installation)
> does change the pixel data.
>     O = R180
> O-R90 = O-R270

I cannot explain the behavior, I assume there is either a tiny logical detail 
that we do not see or some fact deep in the JPEG compression technique.
It's at least symmetric.

If you read my definition closely you will see that is does not require 
O = R90
It only requires any lossless operation R to have an operation R' so that
O = R'RO
;-)

Marcel