Image editing experts: Is there a tool for doing this??

[Ichinisan]

I have a photograph of a document, taken at a slight angle. Is there a software effect that allows me to select the corners (forming a trapezoid shape), then flatten the perspective as if the document had been scanned?

1) I'm certain that such an effect exists, but what is it called? (hard to Google without knowing this)

2) Is there any free software or web site that can do it?

Thanks!

 

[kranky]

The effect is "deskewing"

 

[Ichinisan]

The effect is "deskewing"

Thank you!