Re: jpegtran lossless rotation?

[Olaf Conradi <oohlaf@gmail.com>]

On Tue, 25 Jan 2005 12:32:27 +0100, Olaf Conradi <oohlaf@gmail.com> wrote:
> On Tue, 25 Jan 2005 17:59:24 +0900, Victor Munoz
> <vmunoz@macul.ciencias.uchile.cl> wrote:
> > I don't know if these differences are relevant, but I guess, if I want to be
> > sure I'm preserving every bit of information :-), then I should use jpegtran to
> > rotate and then decode, not decode and then rotate.
> 
> It does not matter if you keep the rotated image in a bitmap or other
> lossy kind of data format.

   ^^^^ typo: should be lossless ofcourse :)

> So if you want to have the rotated image available in jpeg format,
> then you should rotate with jpegtran and not decode, rotate and
> encode. As the encoding step is the one which loses some information,
> because jpeg uses a lossy compression technique.
> 
>  -Olaf
> 

 -Olaf