GIMP -- How to use Perspective tool?

[Mike Buckley]

I'm trying to figure out how to use the Perspective tool. I can't tell what the numbers in the transformation matrix indicate. I also can't determine how to move, as an example, the top left corner and the top right corner toward the center the exact same amount. I also can't determine how to move them to the right and left without lowering or raising them.

The manual is unhelpful about this stuff. Any help is greatly appreciated!

[Donald]

Mike

I'm afraid I never pay any attention to all those numbers in the matrix. I do it all by eye.

I select 'Number of Lines' under 'Guides' and dial in about 20 or 25. Then just click on the image to lay that grid on it and drag the corners 'til it feels/looks right. If I've then got it wrong, I just 'undo' and start again.

[Mike Buckley]

Thanks, Donald. I assumed more control is available but apparently not. The rulers at the side and top do make it possible to measure the distances somewhat, but only somewhat because I don't see any way to change the scale of those rulers.

I really like the option of being able to automatically crop to the change that was made without having to do that manually as a separate step. That's very cool.