How to select deep corners

[Andy242059334f8j]

Is there a way to select deep corners?  The closest I can get is:

1. Duplicate layer
2. Adjust Offset and Gamma Correction (Image > Exposure) to extreme values so that there is extreme contrast between color and white background
3. Use Magic Want Tool to select white background area.
4. Select Grow (Select > Grow) to increase selection area.

But it still leaves an area of white background unselected in the deepest corners.

Here is a photo, notice my selection.

[D Fosse]

Select > Color Range with the appropriate tolerance is probably better as a one-click solution if that's what you want.

You can also try to uncheck "contiguous" in the Magic Wand options.

What I would do here is simply to inspect all areas and add to selection wherever necessary. But that's just my deep distrust of automatic procedures of any kind 😉