Hi Nik and all,
when using the perspective adjustment and then zoom back out again, the black void triangles form between the trapezoid image and the rectangle box as described the user guide. Especially with dark areas in the affected areas of the image, there is hardly contrast visible. Hence it would be extremely helpful of those triangular voids between the trapezoid and the rectangle could be displayed in a bright red, or some other user selectable color.
Or does anyone have a hint how to get away from a trial and error approach when trying to maximize the amount of image data or crop without voids when using perspective?