1080i vs 1080p

One of the most common enquries we get from customers looking to buy a new HD Ready TV is regarding the difference between 1080i and 1080p. It is generally accepted that a 1080 TV is better than a 720 TV due to their ability to display more lines and hence give a more clear and higher quality picture, so in this article we will concentrate on the difference between a 1080i (interlaced) and 1080p (progressive) signal.

1080i

1080 stands for 1080 lines of vertical resolution. The term implies a horizontal definition of 1920 pixels, so we can say that 1080i TVs have a resolution of 1920×1080 pixels, or about 2.07 million pixels.

To give you an idea of the difference in quality between HDTV and conventional TVs, traditional broadcasting programmes have a maximum of 480 lines, so you can imagine the difference in quality given that the new 1080i LCD TV’s have more than double the capacity.

The letter at the end of 1080i describes the type of scan the television uses to display the picture. “i” stands for interlaced. That means the picture is scanned in two passes, or “fields,” each lasting 1/60th of a second. The first pass fills in the odd numbered lines, leaving the even numbered lines blank, which are filled in by the second pass. Because each field takes 1/60th of a second, and there are two of them, 1080i actually needs 1/30th of a second to convey a full frame. Because human vision works by retaining images for a brief period of time on the eye’s retina, the interlace scan process makes two separate scans of an image appear as one frame.

1080p

1080p is commonly referred to as True HD and is the highest quality of HD.

1080p also provides a resolution of 1920×1080 pixels, but that’s where the similarities with 1080i stop. The letter “p” at the end of 1080p stands for “progressive”. This means that the picture is scanned in a single pass (rather than in two passes with interlaced formats), which makes for a smoother, cleaner image, especially with sports and other motion-intensive content.

Conclusion

If you are still unsure of which to choose, we recommend going for the 1080p as it is the highest quality and will also be the format of the future once the technology becomes standard.