- 2076 Bhadra · 11 marks
Compare RGB, CMY and HSB models
Short answer
RGB is additive for screens using red, green, blue light. CMY is subtractive for printing with cyan, magenta, yellow inks. HSB describes colour by hue, saturation, brightness, matching human perception and enabling intuitive adjustment.
Comparisons between RGB colour model, CMY colour model and HSB colour model.
A colour model is a mathematical way of specifying colours. RGB and CMY are device-oriented models (based on how devices produce colour), while HSB is a perception-oriented model (based on how humans describe colour).
Short description
- RGB: additive model. Colours are produced by mixing red, green and blue light. Each component is 0-255 (24 bits per pixel, 16.7 million colours). Black is (0,0,0) and white is (255,255,255).
- CMY: subtractive model. Colours are produced by cyan, magenta and yellow pigments that absorb light from white paper. Relation: C = 1 - R, M = 1 - G, Y = 1 - B. In printing, a black ink K is added (CMYK) since mixing C, M, Y gives a muddy brown.
- HSB: Hue (colour type, 0-360 degrees on the colour wheel), Saturation (purity of colour, 0-100%), Brightness (value, 0-100%). It matches the way an artist describes colour, for example "a dull dark blue".
Comparison table
| Point | RGB | CMY | HSB |
|---|---|---|---|
| Type | Additive | Subtractive | Perceptual (cylindrical) |
| Components | Red, green, blue | Cyan, magenta, yellow | Hue, saturation, brightness |
| Basis | Emitted light | Reflected light, ink absorption | Human colour perception |
| Origin | Black | White | Colour wheel / cone |
| White | (255,255,255) | (0,0,0) | any H, S = 0, B = 100% |
| Black | (0,0,0) | (255,255,255) in theory | B = 0 |
| Used in | Monitor, TV, camera, scanner | Colour printers, publishing | Colour picker, image editing |
| Intuitive for user | Difficult to adjust a shade | Difficult | Easy: change one value for lighter or more pure |
| Device dependent | Yes | Yes | Depends on RGB it came from |
| Conversion | Base model; the others are derived from it | From RGB by simple subtraction | From RGB by non-linear formulas |
Example: orange
- RGB = (255, 165, 0)
- CMY = (0, 90, 255)
- HSB = H about 39 degrees, S = 100%, B = 100%
To make the orange darker in HSB, only lower B. In RGB, both R and G would have to be scaled down together to keep the same hue.
Summary of use
RGB for anything shown on a screen, CMY (CMYK) for anything printed, HSB when a person must choose or edit colours easily.
Conversion formulas
- RGB to CMY: C = 1 - R, M = 1 - G, Y = 1 - B (values 0 to 1).
- RGB to HSB: B = max(R,G,B); S = (max - min) / max; H is found from which channel is largest, e.g. if R is max, H = 60 x ((G - B)/(max - min)) degrees.
- Check with orange (1, 0.647, 0): B = 1, S = (1 - 0)/1 = 1, H = 60 x (0.647 - 0)/1 = 38.8 degrees, which matches the 39 degrees above.
Which to choose
| Task | Model |
|---|---|
| Programming a display or web colour | RGB |
| Sending a design to a printer | CMY / CMYK |
| Designing a colour scheme, adjusting shade or tint | HSB |
None of them is better in all cases; the colours must be converted when an image moves from screen to paper, and some bright screen colours cannot be printed.
✓ Answer checked by Claude Opus 5.5 (high effort)
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