Re: The orientation attribute and -orient command

On Wed, 22 May 2013, Glenn Randers-Pehrson wrote:

> 
> On Mon, May 20, 2013 at 12:58 PM, hack bear <[email protected]> wrote:
>
>       Since I only interested in orienting (i.e. rotate by multiple of 90 degrees) I would guess -orient may be faster
>       than -rotate.
> 
> 
> Looking at the source code for RotateImage()$, it appears that such cases are detected and handled by IntegralRotateImage() .

That is true.  The rotation speed would be identical.  However, a 
clever person can defer that rotation (by marking the image) so that 
it has to be done by the recipient user.  This would be based on an 
expectation that the recipient has smart softare which auto-rotates 
the image.

Until GM edits EXIF tags, the issue is moot.

Even when GM edits EXIF tags, GM will still not be the best way to 
rotate a JPEG image.  The 'jpegtran' utility would do a better job 
since it uses a lossless method to rotate the JPEG.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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