---
title: "HSB versus YUV colour model"
subject: "Multimedia System"
chapter: 3
key: "semester_8/multimedia_system:hsb-vs-yuv"
source: https://www.bctengineer.com/q/semester_8/multimedia_system/hsb-vs-yuv
site: BCT Engineering
---

# HSB versus YUV colour model

Multimedia System · Chapter 3: Images and Graphics

- Asked in: 2073 Bhadra, 7 marks; 2072 Magh, 6 marks (asked 2 times)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/multimedia_system/hsb-vs-yuv
- Whole chapter: https://www.bctengineer.com/md/semester_8/multimedia_system/chapter-3

## Question

Differentiate between the HSB colour model and the YUV colour model.

## Short answer

HSB describes colour by hue, saturation, brightness, matching human perception; YUV separates luminance Y from chrominance U,V for TV and compression. YUV allows black-and-white compatibility and chroma subsampling.

## Answer

**HSB** (also HSV) describes colour the way people perceive it: hue, saturation and brightness. **YUV** separates a colour into one luminance (brightness) component Y and two chrominance (colour-difference) components U and V; it was developed for colour television.

| Point | HSB | YUV |
|---|---|---|
| Components | Hue (H), Saturation (S), Brightness (B) | Luminance (Y), chrominance U and V |
| Meaning | H: the colour type (angle 0-360 degrees); S: purity, 0-100%; B: brightness (value), 0-100% | Y: brightness; U = B - Y and V = R - Y (scaled) |
| Based on | Human perception, intuitive for artists | Television signal needs and the eye's lower sensitivity to colour detail |
| Derived from | Transformation of RGB cube | Linear transformation of RGB |
| Main use | Colour pickers, image editing, selecting colours | PAL TV, video compression (JPEG/MPEG use the similar YCbCr) |
| Compatibility | None needed | Y alone gives a black-and-white picture, so colour signals work on old B/W sets |
| Compression benefit | None directly | U and V can be sub-sampled (4:2:0), saving bandwidth |
| Conversion | Non-linear formulas | Linear matrix |

#### Formulas for YUV

- Y = 0.299 R + 0.587 G + 0.114 B
- U = 0.492 (B - Y)
- V = 0.877 (R - Y)

Example: pure red (R = 1, G = 0, B = 0): Y = 0.299, U = 0.492 x (0 - 0.299) = -0.147, V = 0.877 x (1 - 0.299) = 0.615. A grey pixel has U = V = 0.

#### Example for HSB

Pure red is H = 0 degrees, S = 100%, B = 100%. Pink is the same hue with lower saturation (S = 40%). Dark red is the same hue and saturation with brightness 50%.

HSB is chosen when a person must pick and change colours; YUV when data has to be transmitted or compressed efficiently.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which are the components of the HSB and YUV models?
   A. HSB: hue, saturation, brightness; YUV: luminance Y and chrominance U, V
   B. HSB: luminance and chrominance; YUV: hue, saturation, brightness
   C. Both: red, green, blue
   D. HSB: cyan, magenta, yellow; YUV: red, green, blue
   Answer: A. HSB uses hue, saturation, brightness; YUV uses one luminance and two chrominance components. (Key point: Components)

2. Why was YUV useful for colour television?
   A. Y alone gives a black-and-white picture, so colour signals still work on old B/W sets
   B. It needs no luminance
   C. It matches artists' intuition
   D. It removes the need for chrominance
   Answer: A. The Y component alone gives a B/W picture, giving compatibility with old sets. (Key point: Compatibility of YUV)

3. What compression advantage does YUV give?
   A. Y can be sub-sampled to save bandwidth
   B. U and V can be sub-sampled (e.g. 4:2:0) because the eye is less sensitive to colour detail
   C. None; it is the same as HSB
   D. All components must be kept at full resolution
   Answer: B. The eye is less sensitive to colour detail, so U and V are sub-sampled to save bandwidth. (Key point: Compression benefit)

4. What are U and V for a grey pixel?
   A. Both equal to 1
   B. Equal to Y
   C. U is 0.5 and V is 0.5
   D. Both are 0
   Answer: D. A grey pixel has R = G = B, so B - Y and R - Y are zero and U = V = 0. (Key point: Grey pixel in YUV)

## Related in Multimedia System

- [RGB versus CMY colour model](https://www.bctengineer.com/question.md?key=semester_8%2Fmultimedia_system%3Argb-vs-cmy) — Multimedia System, chapter 3, asked 3×
- [CMYK colour model and application](https://www.bctengineer.com/question.md?key=semester_8%2Fmultimedia_system%3Acmyk-colour-model) — Multimedia System, chapter 3
- [Compare RGB, CMY and HSB models](https://www.bctengineer.com/question.md?key=semester_8%2Fmultimedia_system%3Argb-cmy-hsb-comparison) — Multimedia System, chapter 3

## Related in other subjects

- [Colour versus streak of mineral](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Acolour-versus-streak-of-mineral) — Engineering Geology I, chapter 3