Photoshop Has a Serious Flaw in it’s Color Calculations

While fiddling with the commands under Mode>Adjustments menu, I learned that the color circle used by Photoshop is purely and simply wrong. This stupid programmers thought that yellow and blue are complementary colors, where even high school art students knows that orange and blue are complements, like red and green.

I have seen a wide variety of different color circles in the published literature, and I believe most of them are incorrect. Here I am offering a solution to this problem.

The real problem is mapping the visual spectrum of light onto the color circle, and the solution is to notice that there is no color beyond blue. Indigo does not exist; it is a myth. The spectrum contains only five colors (ROYGB), and indigo is simply a very black shade of blue.

This observation makes the mapping problem trivial, since there are six colors on the color circle, the sixth of which is an even mixture of the two ends of the spectrum – red and blue. That color is magenta, although I prefer to call it purple. As an aside, you can see that purple doesn’t exist in nature, but is a fiction created by human neurology to allow our brains to map the visible spectrum into a circle.

Because it’s the the color of the sun, which is what our eyes are our eyes key on, yellow is at both the center of the spectrum and at the top of the color wheel. Every 60 degrees around the circle, you get a new color, green at 60, blue at 120, orange at -60 and red at -120. That puts purple directly at the bottom of the circle (180 degrees), making it the complement of yellow. The line between Yellow and Magenta is the "axis" of the circle.

It also explains why Photoshop compresses the Orange range so annoyingly, as well as making it numerically hard to find, since pure orange doesn’t have round number indices under either the RGB, CMY or LAB systems. And it gives some engineering insight into the RGB and CMY representations. CMY is the system used for printing, which means that it was invented long before color monitors and their RGB system. CMY is accepted as the de facto standard for Photoshop settings, while RGB is only a second class standard.

Magenta and Yellow are at the 0 and 180 degree points, while Cyan, which is perfectly halfway between Blue and Green, is exactly 90 degrees from the Magenta/Yellow boundary. This dovetails perfectly with the NTSC system of compressing three color channels into two signals, by subtracting them from each other to define only "luminance" and "chrominance" signals.

My model says that the NTSC Luminance channel is the same as the Magenta/Yellow channel, and acts as a "gross adjustment" knob. The Cyan channel is exactly perpendicular to the Magenta/Yellow channel, making it the "fine tuning" adjustment.

RGB is a rough approximation to this fine/coarse system of adjustment. Again, Red/Green are direct opposites on the color wheel, but now Blue is slightly different from perpendicular, with a 60 degree offset, rather than 90 degrees. The inaccuracies built into RGB are a historical accident, based on engineers’ ability to find good material for phosphors in the 1950’s, when color TV was invented.

And it’s another reason why the Orange range is so compressed, when it shouldn’t be. Blue and Green are bad choices for orthogonal colors, because they’re right next to each other on the color circle. The Orange range is compressed is because it’s opposite the B/G region, while the B/G range is equivalently expanded, wasting part of the color space.

Using ROYGB for the spectrum and ROYGBM for the color wheel simplifies the mathematics of complex color calculations enormously. Among the many stupidities it eliminates is the mistake of using obviously wrong color circles with yellow and blue as complementary colors. That’s clearly trying to jam a square peg into a round hole, and anybody should be able to see that it’s a serious weakness in Photoshop.

Does anybody have any i