Re: [Gimp-user] Unskewing images of flat rectangular objects in Gimp

[Steve Kinney <admin pilobilus net>]

On 02/04/2013 03:46 AM, Elmer Wix wrote:
> Øyvind Kolås <pippin 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)?

I has a "well DUH!" moment over this because I never noticed the
function, so I started tinkering around with it.  If there is a
rectangular selection on the canvas, the area selected by the
perspective tool conforms to the selection when resampled.  The tool
options dialog dock for Rectangular Select has settings for
adjusting the size and position of the selection in pixels.

I can't believe the amount of time I have wasted squaring up
photographed or scanned rectangular objects "by hand."  But I love
it when posters like Øyvind point out things that should have been
obvious to me - better to learn late than never!

:o)

Steve