i use OKLCH color picker to choose colors for my pictures

the steps

1. i pick grey colors (without chroma) so i can see the contrast

   

2. then i add chroma and hue

   

Lightness

i use 12 lightnesses:

• 

  0 %

• 

  ¹⁄₁₂ = 8.33 %

• 

  ²⁄₁₂ = 16.67 %

• 

  ³⁄₁₂ = 25 %

• 

  ⁴⁄₁₂ = 33.33 %

• 

  ⁵⁄₁₂ = 41.67 %

• 

  ⁶⁄₁₂ = 50 %

• 

  ⁷⁄₁₂ = 58.33 %

• 

  ⁸⁄₁₂ = 66.67 %

• 

  ⁹⁄₁₂ = 75 %

• 

  ¹⁰⁄₁₂ = 83.33 %

• 

  ¹¹⁄₁₂ = 91.67 %

• 

  100 %

if i want clear contrast between a background color and a foreground color, i make the foreground 5 steps lighter/darker than the background.

if i want visible contrast, the 2 Lightnesses are 4 steps away from each other.

if i want almost no contrast, the Lightnesses are only 1 – 3 steps away.

Hue

i may use any of the 360 hues.

when the Lightness between 2 same-hue colors gets lighter by 1 step, the hue gets 5° closer to red/yellow.

when it gets darker instead, the hue gets 5° closer to blue/purple.

Chroma

i don't have a system for choosing Chroma, except that i snap it to sixths:

• 

  0

• 

  ⅙ × 0.1 = 0.02

• 

  ²⁄₆ × 0.1 = 0.03

• 

  ³⁄₆ × 0.1 = 0.05

• 

  ⁴⁄₆ × 0.1 = 0.07

• 

  ⁵⁄₆ × 0.1 = 0.08

• 

  0.1

• 

  ⁷⁄₆ × 0.1 = 0.12

• 

  ⁸⁄₆ × 0.1 = 0.13

• 

  ⁹⁄₆ × 0.1 = 0.15

• 

  ¹⁰⁄₆ × 0.1 = 0.17

• 

  ¹¹⁄₆ × 0.1 = 0.18

• 

  2 × 0.1 = 0.2