> Date: Mon, 4 Feb 2013 00:46:53 -0800
> From: elmer.cabekaziruronometu....@gmail.com
> To: gimp-user-list@gnome.org
> Subject: Re: [Gimp-user] Unskewing images of flat rectangular objects in Gimp
> Øyvind Kolås <pip...@gimp.org> wrote:
> > The perspective tool has an inverse mode, if you align the grid lines
> > from the wireframe preview with the lines desired to become
> > horizontal/vertical and then do the transform you should end up with a
> > rectified version of the quadliteral.
> Thanks!  That worked.  The size and aspect ratio of the rectified
> quadrilateral isn't always close to what I want it to be, though.  Is
> there a way to specify this before I do the perspective transform, or
> do I just need to do it in 2 steps (correct perspective, and then
> re-size)?

 is certainly an issue - the perspective tool would really benefit from 
having an option to automatically preserve the x/y aspect ratio (much like 
scaling already does), though 
exactly how it would work mathematically I don't know.  I've found that 
if you note the [1,1] and [2,2] numbers in the transformation matrix you
 can do a manual rescale using those values as your X and Y scalars and it 
really helps, but it's not exact since it doesn't take rotations into account.

-- Stratadrake
Numbers may not lie, but neither do they tell the whole truth.

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