How to flatten a curved paper photo?

[brillywu]

Hi,
I have a photo of test paper.When taking this picture, the paper was not laid flat. Now I'd like to flatten the curved part. How to do it? thank a lot.

[denzjos]

Some explanation about the item you are looking for is find in this forum : 

https://www.gimp-forum.net/Thread-correc...f-all-kind

[rich2005]

It is going to depend on how many of these you have to process. No real automatic way that I know of, maybe someone will come up with something.

This using (1) Adjust the whole page with a trapezium deform then (2) the table with the gmic plugin - http://www.gmic.eu - interactive warp filter.  Never going to be wonderful and very user intensive.

   

and a 5 minute video how I got there: https://youtu.be/xRR0RbizQJA

[brillywu]

thanks rich2005 & denzjos. I have chosen this one:“curve-bend-between....", it is easy to use.

[Ofnuts]

This only fixes the vertical shift caused by the distance to the lens. But the parts in the fold are also horizontally squeezed (the QR code isn't square). This can perhaps be fixed with a displace map.