The Relationship between Levels and Curves

Both the Levels and Curves are set for RGB mode. This also shows that Photoshop takes no notice of the colours in the picture only the greyscale. To show the relationship between Levels and Curves four points have been chosen. One in the darkest area, one in the lightest and two in between. It is as if the histogram from levels is removed from its box and angled though 45 degrees and stood on edge. This is shown below.