You can keep one of the dimensions by making a histogram a 3d surface. 3d surface f(x,y)->z can be displayed as flat image with brightness representing z value.

You can keep one of the dimensions by making a histogram a 3d surface. 3d surface f(x,y)->z can be displayed as flat image with brightness representing z value. Brightness can be displayed using dithering. Putting all that together would result in more or less the same diagrams as described in article. With biggest difference being that information about left part of image is actually visible. Swapping x with brightness is a bit misleading as dithering effect of white dots on black background give much stronger feeling of varied brightness than actual brightness.