1080i vs 1080p

What's the difference between 1080i and 1080p?

Young cinematographer on set with camera

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1080i and 1080p are both High Definition display formats, and actually represent the same pixel resolution (1,920 pixels across the screen by 1,080 pixels down the screen or about 2 million pixels total). The difference between 1080i and 1080p lies in the way the signal is sent from a source device or displayed on an HDTV screen.

  • In 1080i, each video frame is sent or displayed in alternative fields. The fields composed of 540 rows of pixels or lines of pixels running from the top to the bottom of the screen, with the odd fields displayed first and the even fields displayed second. Together, both fields create a full frame, made up of all 1,080-pixel rows or lines, every 30th of a second. 1080i is most commonly used by TV broadcasters, such as CBS, CW, NBC, and many cable channels.
  • For 1080p, each video frame is sent or displayed progressively. This means that both the odd and even fields (all 1,080-pixel rows or pixel lines) that make up the full frame are sequentially displayed, one following the other. The final displayed image is smoother looking than 1080i, with fewer motion artifacts and jagged edges. 1080p is most commonly used on Blu-ray discs and selected streaming, cable, and satellite programming.

Differences Within 1080p

There are also differences in how 1080p is displayed with regards to the frame rate. Here are some examples:

  • 1080p/60 represents the same frame repeated twice every 30th of a second (enhanced video frame rate).
  • 1080p/30 is the same frame displayed once every 30th of a second (recorded or live video frame rate).
  • 1080p/24 is the same frame displayed every 24th of a second (standard motion picture film frame rate).

The Key Is in the Processing

How 1080i and 1080p look on your TV screen depends both on the content and processing capability of the source player (upscaling DVD player, Blu-ray disc player, media streamer, or even a home theater receiver), or using the HDTV before the image is displayed. There may or may not be a difference in having the TV do the final processing (referred to as deinterlacing) step of converting 1080i to 1080p.

This is especially important as although CRT HDTVs can display 1080i natively, LCD, Plasma, and OLED TVs display images progressively. This means that incoming 1080i video signals must be converted to either 720p, 1080p, or even 4K for screen display.

Processors used in TVs may yield similar or the same results as the processors used in many DVD or Blu-ray disc players.

1080p, 1080i, and Blu-ray Disc Players

With Blu-ray, the information on the disc is 1080p/24 as that reflects movie frame rate. There are some instances of content being placed on a Blu-ray disc in either 720p/30 or 1080i/30, but those are exceptions, not the rule.

Most Blu-ray disc players can output 1080p/24 or 1080p/30/60 video to a compatible TV. This means that no matter what 1080p TV you have, you should be fine as the player can convert the output signal to 1080p/30/60 to accommodate specific TVs.

However, there are variations in how some players accomplish this task. The following are two interesting examples from two players that are no longer in production but are still in use.

The first example is the LG BH100 Blu-ray/HD-DVD combo player (no longer in production). Since, at the time of its release, not all HDTVs could display 1080p/24, when the LG BH100 is connected to an HDTV that does not have 1080p/24 input and display capability but only has 1080p/60/30 or 1080i input capability, the LG BH100 automatically sends its 1080p/24 signal from the disc to its own video processor which then outputs a 1080i/60 signal. In other words, this player can only output a 1080p signal if the TV is 1080p/24 compatible. This leaves the HDTV to do the final step of deinterlacing and displaying the incoming 1080i signal in 1080p.

Another example of 1080p processing is the Samsung BD-P1000 Blu-ray disc player (no longer in production). What it does is even more complicated. This Blu-ray player reads the 1080p/24 signal off the disc, then it actually re-interlaces the signal to 1080i, and then deinterlaces its own internally made 1080i signal in order to create a 1080p/60 signal for output to a 1080p input capable television. However, if it detects that the HDTV cannot input a 1080p signal, the Samsung BD-P1000 just takes its own internally created 1080i signal and passes that signal through to the HDTV, letting the HDTV do any additional processing.

Just as with the LG BH100, the final 1080p display format depends on what deinterlacing processor is used by the HDTV for the final step. It may be that a specific HDTV has a better 1080i-to-1080p processor. In this case, you may see a better result using the HDTVs processor rather than the player.

The LG BH100 and Samsung BD-P1000 are not typical of most Blu-ray disc players, with regards to how they handle, 1080i/1080p issues, but they are examples of how both of these resolution formats can be handled, at the discretion of the manufacturer.

1080p/60 and PC Sources

When you connect a PC to an HDTV via DVI or HDMI, the graphics display signal of the PC may indeed be sending out 60 discrete frames every second (depending on source material), instead of repeating the same frame twice, as with film- or video-based material from DVD or Blu-ray disc. In this case, no additional processing is required to "create" a 1080p/60 frame rate via conversion. Computer displays typically don't have a problem accepting this type of input signal directly, but some TVs might.

The Bottom Line

Regardless of your source device or TV, how the image looks to you is what is important. Short of having a tech come out and doing actual measurements, or comparing results using different TVs and source components yourself, as long your HDTV has internal processing to do the job, you are set.