Broadcast television in regions that adopted Phase Alternating Line (PAL) and SECAM used this Standard Definition (SD) raster for the everyday picture. It is not a High Definition (HD) mode. A stored frame holds about 720×576 pixels, and 576 counts the active vertical lines.
The letter i means those lines arrive as two fields that together make one frame. The scan draws 50 fields per second, which pair into 25 frames per second. The line count is higher than in National Television System Committee (NTSC) 480 Interlaced (480i), so a PAL picture has slightly more vertical lines. The same vertical count drawn in a single pass is 576 Progressive (576p).
How Two Fields Make One Frame
- Odd and Even Lines. One field holds the odd-numbered lines and the next field holds the even-numbered lines. The pair is one frame.
- Field Timing. A new field starts every fiftieth of a second. A still grab of motion can show combing because the two fields were not taken at the same instant.
- Same Class as the Shorter Raster. More lines than 480i do not move this picture into HD. Both are standard-definition interlaced television.
Pixels and Display Shape
- Stored Samples. The usual digital frame is about 720×576. Those counts form a 5:4 grid, which matches neither common display shape.
- Display Aspect. The picture is shown at 4:3 or 16:9. Samples are not square, so the display stretches them into the chosen shape rather than trusting the raw grid.
- Progressive Partner. 576p keeps this pixel count and paints every line on each pass. 480 Progressive (480p) does the same job for the shorter NTSC line count.
The Wider Scan Family
Larger modes are a different class of picture. 720 Progressive (720p) is the first common high-definition step. 1080 Interlaced (1080i) and 1080 Progressive (1080p) use 1,080 active lines, and Full High Definition (FHD) names the progressive raster at that line count. 1440 Progressive (1440p), also called Quad High Definition (QHD), steps up again. 2160 Progressive (2160p) and 4320 Progressive (4320p) continue that climb. None of these modes is this standard-definition field scan.
| Mode | Typical Pixels | Scan | Usual Rate |
| 480i | 720×480 | Interlaced | 59.94 fields per second |
| 480p | 720×480 | Progressive | 59.94 frames per second |
| 576i | 720×576 | Interlaced | 50 fields per second |
| 576p | 720×576 | Progressive | 50 frames per second |
| 720p | 1280×720 | Progressive | 50 or 60 frames per second |
| 1080i | 1920×1080 | Interlaced | 50 or 60 fields per second |
| 1080p | 1920×1080 | Progressive | 24, 50, or 60 frames per second |
| 1440p | 2560×1440 | Progressive | 60 frames per second |
| 2160p | 3840×2160 | Progressive | 24, 50, or 60 frames per second |
| 4320p | 7680×4320 | Progressive | 50 or 60 frames per second |