Difference Between 720 & 1080 PPI LCD Televisionsby Steve McDonnell
A 720 PPI LCD television provides 720 pixels per inch on the television screen. A 1080 PPI LCD TV provides 1,080 pixels per inch. More pixels create a higher-resolution picture. However, the perceived quality of the picture also depends on the distance at which you view the television, whether you view text on the screen and the kind of high-definition broadcast your LCD HDTV receives, either interlaced or progressive.
A 720 PPI LCD television provides a lower resolution than a 1080 PPI LCD TV. Your LCD television has many pixels -- small shapes -- that are lit in different colors to make up the picture. The more pixels you have, the greater the resolution. Now think of the pixels as being grouped together into horizontal and vertical lines. A 720 PPI LCD TV provides 921,600 pixels grouped into 1,280 horizontal lines and 720 vertical lines. A 1080 PPI TV provides 2,073,600 pixels grouped into 1,920 horizontal lines and 1,080 vertical lines. More pixels means more lines, a higher resolution and, in theory, a better picture.
Perceived Quality and Distance
The difference in the picture quality between a 720 LCD TV and a 1080 LCD TV is most noticeable the closer you sit to the TV. According to CNET, if you set a 50-inch 720 LCD TV and a 50-inch 1080 LCD TV side by side, you have to sit six-and-a-half feet or closer to the televisions to notice a difference in the picture quality. The further away you sit, the harder it is to discern a difference in the picture quality.
Using Your LCD TV as a Computer Monitor
If you plan to use your LCD TV not only as a TV but also as a computer monitor, the difference in quality may be much more noticeable. If you're simply using your computer to display a movie, it won't make much difference. However, if you're using the LCD TV to read text on the monitor, the text will be harder to read on a 720 PPI LCD TV and you will have to sit closer to the monitor than you would when viewing on a 1080 PPI LCD TV.
Interlaced vs. Progressive
The source of the picture you broadcast on your LCD TV noticeably affects the quality of the picture. A source that broadcasts in 720 PPI may broadcast in 720i or 720p. Similarly, a source that broadcasts in 1080 may broadcast in 1080i or 1080p. The "i" stands for "interlaced," which means the odd lines are broadcast and then the even lines are sent. The "p" stands for "progressive," meaning that all pixels are broadcast at the same time until the picture is sent. Especially for pictures that involve fast motion, a progressive source provides a better picture than an interlaced source.
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