Adjust the colormap used to render the image to a 40x40 (e.g.) pixels ROI around the current cursor position. This should be done dynamically, i.e. as the cursor moves, the colormap is adjusted. The behaviour is obtained when a keyboard key (e.g. w) is pressed as the mouse moves.

The original colormap (min/max or mean +/-3 stds) could be restored by pressing another key.