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Filmmaking Dictionary: Number 1 / 1080p / 1080i (Full HD)
Definition
1080p and 1080i describe video with 1,080 active picture lines. A common Full HD raster is 1920 × 1080. The suffix identifies the scanning structure: p means progressive and i means interlaced.
Resolution and scanning structure are only part of the format. Frame rate, field rate, pixel aspect ratio and the recording or delivery specification also need to be known.
Progressive Frames
Progressive video presents complete frames. In a 1080p25 signal, there are 25 complete frames per second. In a 1080p50 signal, there are 50. Both have the same nominal picture dimensions but different temporal sampling.
This distinction affects motion portrayal, camera settings and conversion to another frame rate. The word ‘1080p’ alone does not tell an editor how quickly the pictures were captured.
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Interlaced Fields
Interlaced video divides the image into two fields containing alternating lines. In true interlaced capture, the fields represent different moments in time. A 50-field-per-second signal contains 25 frame pairs per second; a 59.94-field-per-second signal contains approximately 29.97 frame pairs.
Naming conventions can be confusing. ‘1080i50’ commonly indicates 50 fields per second, while another specification may describe the same system using its frame rate. Confirm whether a quoted rate refers to frames or fields.
Why Motion Can Look Combed
If two fields captured at different times are displayed together as though they were one progressive image, a moving edge can show horizontal comb-like lines. Proper deinterlacing interprets the field structure to create a suitable progressive output.
Incorrect field order can also produce awkward motion. Changing a file’s label without processing the image does not necessarily convert interlaced footage correctly.
Checks in a Production Workflow
- Match the recording format to the agreed delivery requirements.
- Confirm whether motion was captured progressively or interlaced.
- Check frame rate, field rate and field order.
- Review movement in the exported file.
- Distinguish progressive segmented frame transport from true interlaced capture.
Progressive segmented frame, or PsF, transports a progressive image in segments. Its structure should not be mistaken for two fields representing different capture times.
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Frequently Asked Questions
Does 1080i contain only 540 lines?
Each field contains alternating lines, but the nominal full picture has 1,080 active lines.
Is 1080p always better-looking than 1080i?
The source, rate, conversion and display all matter. Use the correct format for the workflow and avoid accidental reinterpretation.
Related Terms
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