XnView Software

I've already done this in GIMP: set "G" as the toggle to turn the grid on & off. Would make sense to do it in Xnview too.

Cropping lots of photos from a DSLR is a big task because the 3:2 ratio of many cameras does not match many paper sizes or not all the picture is wanted in the printed version.

Scenario 1 : 10 DSLR images to crop for printing or resizing.

To get a fixed ratio crop you first need to use Edit | Set ...