If I don't know the aspect ratio of an image, what is the most efficient method to set the selection aspect ratio to that of the image? The fastest I've found (not fast at all) is to look at the window title and enter the full image dimensions in the aspect ratio text box (e.g.,
For reference, the Digikam image editor has this functionality as a simple drop box entry in the cropping tool:
The fastest way I can think of:
Select your selection tool (rectangle select or circle select)
It isn't necessary to do this first, but it's necessary for step two.
CtrlA to select all
Enable Fixed in the selection tool options:
Click on the selection to make the scaling handles appear, and scale the selection