Generating a color spectrum for an image

This is a very interesting project. As a design teacher, I recommend to my students that they do not employ color swatches for anything other than flat color designs. Certainly for an animation, a photo or a movie such simplified visualizations have little value as they do not convey the kind of ranges information this project is addressing.

That being said, I am certain that there is no 2D method of visualizing such fundamentally 3D information as color.

I really like the idea of iteration 7, but I feel like it would work a lot better with some minimum height on the y axis. Letting it peter out to zero loses the "spectrum-ness" of it, and it just looks like various random color blobs. Maybe could have a fixed minimum height, and somehow use saturation to distinguish "truly zero here" from "really low amount here".

Iteration 7 would be interesting as a video (for a video).

I like the final idea, but I think I'd like it better on a log scale -- so many of the colors get basically one or two pixels of height.

Visually the results are very compelling! It also gives an at-a-glance intuition about the image that the bar-style options fail to convey. I am a fan.

Is there source available for this?

Now make it polar and you almost have a vectorscope...