Crop selection – auto detection

When you have simple images in which you have to do some small Crop Selections for cutting an unuseful background and you cannot use the command Select Auto Region (I have rounded corners in my example, attached file) as you need some small parts of that background… you have to zoom your image for cropping exctly your image.

In my example your work is easier as the image is simple and small but the idea is to have a Crop Selection option for auto-detect the smaller image possible when the background is the same colour.

By words, according my example, a way to crop that example image in which the software does its tusk to crop that image to the limit of the colour of the background (grey, in that case).