Color as Numbers

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This is a Multiplication curve...

Curves 02.png

So... why is it called that? And why, for that matter, is the Multiply blend mode called multiply? Why, even... is digital art called digital? Well... they call it digital art because, at its root, it is derived from numbers. Importantly... in the digital world black is 0 (zero) and white is 1 (one). The Curve graph above can be read in the following manner:

  • If 1 is multiplied by 0.5 the result is 0.5.
  • If 0.5 is multiplied by 0.5 the result is 0.25
  • If 0 is multiplied by 0.5 (or indeed any other number) the result is 0.

So... color adjustments are mathematics. These maths are (for the most part) quiet simple.

I will drive this fact home with a small demo. In the image below the left half has had a layer of mid grey (50% brightness) placed above it and set to Multiplication Blend Mode. This will multiply the image by 0.5. The right half has had a 0.5 multiplication curve applied as an adjustment layer. As you can see, they both have an identical effect upon the image.

Curves 04.png

Though its possible to be a digital artist without knowing too much about the underlying maths of what you are doing, you will be a betterr one if you have at least a passing knowledge of them. I am telling you this for a reason: students often stab away at PS's color controls without knowing what they do. 'I just fiddle with them untilo it looks good' is what I often hear. Unless you know how you achieved your successes, then you will not be able to reproduce them.