Hi. A friend has sent me a number of images of documents. He photographed
the documents from an oblique angle. This results in the bottom of the
document being wider than the top. Is there any way in Gimp to widen the
top of the image so that it is the same width as the bottom edge?
On Mon, 2020-06-22 at 03:31 +0200, Pat Brown via gimp-user-list wrote:
> Hi. A friend has sent me a number of images of documents. He
> the documents from an oblique angle. This results in the bottom of
> document being wider than the top. Is there any way in Gimp to widen
> top of the image so that it is the same width as the bottom edge?
the easiest way to do this is to use the perspective tranform in gimp.
1. open an image
2. in the toolbox choose the "perspectivetool" (or, from the tools
3. in Tool Options, switch to Corrective Mode, not Normal Mode. This
makes the operation super easy. Under Guides in tool options, select
Number of Lines and move the slider to 24 or so.
4. click on the image, and some lines should appear. These are the
guidelines you just chose; if you want more, you can move that slider
5.Your goal is to make the guidelines parallel to the edge of the paper
in the photograph. to do that, drag the corners. You'll need to zoom in
and out a bit with the + and - keys (+ may be shifted on yuor
5. when it's about right, press ok (or Transform) in the little floaty
dialogue in the image window. It might say something else depending on
your anguage of course.
6. use image->flatten image, to remove any transparency. This step
isn't needed in all gimp versions.
7. use the crop tool if needed to trim the picture