1080i vs 1080p - Similarities and Differences

1080i vs 1080p - How They Are The Same and Different

Inspecting TV Screen
Inspecting TV Screen. Getty Images - Gavni

1080i and 1080p are both High Definition display formats. 1080i and 1080p signals contain the same information, representing 1920x1080 pixel resolution (1,920 pixels across the screen by 1,080 pixels down the screen). However, 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 in 1080i are 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 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 on how 1080p is displayed.

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. (standard live or recorded video frame rate.)
  • 1080p/24 is the same frame displayed every 24th of a second (standard motion picture film frame rate).

    For more details on how video frames are processed and displayed on a TV, refer to our article: Video Frame Rate vs Screen Refresh Rate

    The Key is in the Processing

    1080p processing can be done at the source (upscaling DVD Player, Blu-ray Disc Player or media streamer), or can be done by the HDTV before the image is displayed.

    Depending on the processing capability of a source device or 1080p TV, 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.

    For example, if the TV is utilizing a third-party or homegrown processor, such as the ones used in LG, Sony, Samsung, Panasonic, and Vizio sets, for example, may yield similar, or the same, results as the processors used in many source components. Any differences may be very subtle, only slightly noticeable on larger screen sizes.

    1080p and Blu-ray Disc Players

    Keep in mind that on Blu-ray, the information on the disc is in the 1080p/24 format (Note: 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 have the ability to output 1080p/24 to a compatible TV in that native form.

    Almost all Blu-ray Disc players are compatible with 1080p/30 and 1080/24 resolution output. 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 on how some players accomplish this task. The following are two interesting past examples from two players that are no longer in production but are in still 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 previous LG BH100 example. The final 1080p display format depends on what deinterlacing processor is used by the HDTV for the final step. In fact, in the Samsung case, it may that a specific HDTV has better 1080i-to-1080p deinterlacer than Samsung has, in which case you may see a better result using the deinterlacer built into the HDTV. In fact, in the Samsung case, it may that a specific HDTV has better 1080i-to-1080p deinterlacer than Samsung has, in which case you may see a better result using the deinterlacer built into the HDTV.

    Of course, both 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

    It is also important to note that 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 discreet 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 what goes inside your source device or TV, how the image looks on your TV 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 1080p internal processing you are set.

    However, 1080i/1080p aren't the only high-definition resolution formats you will encounter, you should also get familiar with the difference between 720p and 1080i, 720p and 1080p, and 4K.