Pixels & resolution
From 720p to 8K: what resolution means, aspect ratios, and why pixel count matters downstream.
A digital image is a grid of tiny dots called pixels (picture elements). Each pixel holds one color. Viewed from a normal distance, the grid disappears and your eye sees a continuous picture. Resolution is simply the size of that grid: how many pixels across, by how many down.
Reading a resolution
Resolution is written width × height. A Full HD signal is 1920 × 1080: 1,920 pixels in each row, 1,080 rows. Video formats are also nicknamed by their height plus a letter — 1080p — where p means progressive (every line drawn in every frame; more on that in the next lesson). 4K and 8K break the pattern and are named for their approximate width.
- Resolution
- 3840 × 2160
- Total pixels
- 8,294,400
- Aspect ratio
- 16:9
- vs. 1080p
- 4.0×
| Name | Resolution | Aspect | Where you'll meet it |
|---|---|---|---|
| 720p | 1280 × 720 | 16:9 | Older displays, some conferencing streams |
| 1080p (Full HD) | 1920 × 1080 | 16:9 | The workhorse of corporate AV |
| WUXGA | 1920 × 1200 | 16:10 | Projectors and many laptops |
| 4K UHD | 3840 × 2160 | 16:9 | Modern flat panels and sources |
| DCI 4K | 4096 × 2160 | ≈ 1.9:1 | Cinema and professional cameras |
| 8K UHD | 7680 × 4320 | 16:9 | Premium displays; rare in corporate AV |
- 720p
- Resolution1280 × 720
- Aspect16:9
- Where you'll meet itOlder displays, some conferencing streams
- 1080p (Full HD)
- Resolution1920 × 1080
- Aspect16:9
- Where you'll meet itThe workhorse of corporate AV
- WUXGA
- Resolution1920 × 1200
- Aspect16:10
- Where you'll meet itProjectors and many laptops
- 4K UHD
- Resolution3840 × 2160
- Aspect16:9
- Where you'll meet itModern flat panels and sources
- DCI 4K
- Resolution4096 × 2160
- Aspect≈ 1.9:1
- Where you'll meet itCinema and professional cameras
- 8K UHD
- Resolution7680 × 4320
- Aspect16:9
- Where you'll meet itPremium displays; rare in corporate AV
Aspect ratio
Aspect ratio is the shape of the image: width divided by height. 16:9 is the standard for video and almost every flat panel. 16:10 is slightly taller and common on laptops and projectors. When the source and display shapes don't match, something has to give — black bars (letterboxing or pillarboxing), cropping, or a stretched image.
Native resolution and scaling
Every flat panel and projector has a fixed physical grid — its native resolution. Any signal that doesn't match has to be scaled (resized) to fit. Displays have scalers built in, and so do many switchers and receivers. Scaling works, but a picture always looks sharpest when the signal matches the panel pixel for pixel, especially fine text from a computer.
Why pixel count matters downstream
Resolution isn't just about sharpness. Every pixel is data that has to travel down cables, through switchers and across networks. Going from 1080p to 4K multiplies the pixels by four, and with them the bandwidth every device in the chain must handle. That single fact drives a lot of product choice, and it's where this chapter is heading.
Key takeaways
- 01Resolution is the size of the pixel grid, written width × height.
- 024K UHD (3840 × 2160) has exactly four times the pixels of 1080p.
- 03Aspect ratio is the image's shape; mismatches cause bars, cropping or stretching.
- 04Displays have a fixed native resolution; other signals must be scaled to fit.
- 05More pixels means more data for every cable, switcher and network link in the chain.
Check your understanding
Q1How many 1080p images fit inside one 4K UHD image?
Q2A projector's native resolution is 1920 × 1200. What is its aspect ratio?
Q3Why does text from a laptop often look softest on a display that isn't at its native resolution?