Resolusi 1080p Vs 1080i

[Michelle Benitone]

Manytimes, I have seen resolution of 1080p and I know that it means 1080 pixels but I also have seen specifications on some HDTVs to be 1080i. So, I want to know the exact difference between them and whether 1080i video quality is available for the laptops too.

I see a range of problems in the answers and comments here (even in some highly-voted answers that provide otherwise very good information) that span from minor deficiencies that need explanation to some serious inaccuracies, so I think that some clarification is needed.

The question is specifically: What is the difference between 1080p and 1080i? so I will start by outlining the main similarities and differences, I'll add some tips on how to choose the best format and then I will proceed to explain the problems that I found here.

Please note that this answer is specifically about HDTV and talks about signals and resolutions that can be transferred with a standard HDMI cable. Other resolutions and frame/field rates are certainly possible but standard HD TV sets, game consoles, Blu-ray Discs etc. use only certain resolutions and frame/field rates described below (or at least they did at the time of writing this answer). Specifically this answer doesn't talk about: Ultra-high-definition television, Super Hi-Vision, Ultra HD television, UltraHD, UHDTV, UHD, 4K, 8K or anything beyond 1080p and 1080i that this question is about.

Both 1080p and 1080i have 1080 horizontal lines of vertical resolutionwhich with a widescreen aspect ratio of 16:9 results in a resolution of 1920 1080 pixels (2.1 megapixels). It is not true that 1080i has a lower vertical resolution than 1080p.

A field contains half of the lines of the frame, either even lines or odd lines, and if one field is composed of even lines, then the next one will be composed of odd lines and so on.

1080p at 25 frames per second: Imagine that you are shooting 25 pictures per second and storing them as bitmaps. Every frame is a full picture from the given instant. Every pixel in that frame was captured at the same time.

1080i at 50 fields per second: Imagine that you are shooting 50 pictures per second but storing only half of the bitmaps every time - sometimes you store the odd lines and sometimes the even lines. (Note that it is not the same as storing pictures with lower vertical resolution.) Every field is a half of a full picture from the given instant. Every pixel in that field was captured at the same time.

without doing some tricks and loosing quality. You don't get any of those problems with progressive video. In addition the video encoding is harder because the codec never has a full frame to work with.

The drawback is that 1080p as currently in use has a frame rate that is only half of the field rate of 1080i so the motion is noticeably less fluid - in fact it's exactly twice less fluid which is a lot. You can see it on large flat TVs that often deinterlace the video to be able to display it on their LCD screens (that, unlike CRT displays, are progressive in nature) which is the cause that they display picture of very high resolution but with jerky motion and some deinterlacing artifacts.

Using progressive 1080p with 50 or 60/1.001 full frames per second in the future has a potential to eventually solve the above problems but it will require a whole new range of studio equipment including cameras, storage and editing systems so it probably won't happen anytime soon. The widely used SDI standard for connecting HD video equipment doesn't have enough bandwidth.

Currently the only way to have a fluid motion with progressive scanning is 720p that has a frame rate that is two times faster than 1080p but the resolution of only 1280 720 pixels (instead of 1920 1080 pixels) which may or may not be a problem for some applications. There is no 720i.

*) For number 2 make sure that your 720p has the frame rate of 50 fps if your target format is PAL or SECAM and 60/1.001 if your target format is NTSC (unfortunately it means that there is no format that can be converted to both PAL/SECAM and NTSC). The reason I recommend using 720p for recording is to greatly simplify the edition process when every frame is complete with no interlacing (throwing out every other line at the end is easier than creating the missing lines if you need them) and you have some extra resolution to work with so you can for example zoom the image slightly without making the result look blurry. (If anyone has any bad experience of using 720p to prepare material for SD PAL or NTSC TV broadcasting then please comment so I could update this recommendation.)

I think that progressive scanning is indeed better in every respect, but if we are not talking theoretically about the idea of interlacing but specifically about 1080p and 1080i standards as used today, then one has to take into account the fact that 1080i is often required for TV broadcasting and converting 1080p to 1080i would result in jerky motion.

Again, yes, progressive is better than interlaced all other things being equal, but progressive video with frame rate that is two times smaller than the field rate of interlaced video (which is the case with 1080p and 1080i) is something very different, especially if interlaced video with high field rate is required for TV broadcasting and the high field rate cannot be reproduced from progressively recorded material with lower frame rate.

[In 1080i] all the odd lines are displayed, followed by all the even lines. This means that only 1/2 the resolution (540 lines or pixel rows) is displayed on the screen at any give time - in other words, only 540 pixel rows are displayed at any given time.

The phrase "only 540 pixel rows are displayed at any given time" is extremely misleading. All 1080 rows-of-pixels usually are displayed at once (and even if they weren't, they'd still appear to be to the human eye), but only half of them will be updated in any given frame. It's effectively the refresh-rate, not the resolution, that's cut in half.

While it is true that the phrase "only 540 pixel rows are displayed at any given time" is extremely misleading, it is not true that the refresh-rate is cut in half, because in 1080i the refresh rate is two times faster than with 1080p so it is actually the other way around.

With 1080i60 you actually get less than 60 fields (or "half frames") per second, but it doesn't mean that you get 30 (or almost 30) complete frames per second. In fact you don't get even a single complete frame per second.

The "i" in resolutions represents 'Interlaced'. Basically meaning every other (horizontal) line is drawn in one frame, and then the opposite lines are drawn in the next frame, leaving it up to your eyes/brain to put the two frames into one complete one.

1080p represents 1920 pixels displayed across a screen horizontally and 1080 pixels down a screen vertically. However, unlike 1080i all pixel rows or lines are displayed progressively, providing the most detailed high definition video image that is currently available to consumers.

1080i represents 1920 pixels displayed across a screen horizontally and 1080 pixels down a screen vertically. This arrangement yields 1,080 horizontal lines (pixel rows), which are, in turn, displayed alternately. In other words, all the odd lines are displayed, followed by all the even lines. This means that only 1/2 the resolution (540 lines or pixel rows) is displayed on the screen at any give time - in other words, only 540 pixel rows are displayed at any given time.

Sometimes an interlaced signal will be a progressive signal split into half frames ( e.g. Some Panasonic cameras have 1080p30 sensor output but (for some reason) write it out to a 1080i60 file. A more common case is of actual half frames, and if you freeze frame you'll see discrepancies between alternate lines in the still image.

Why have interlaced frames at all? Good question. Back in the days of analog video, interlacing was used to allow faster refresh for a given bandwidth and it made some sense. Supporting interlaced frames for digital video seems to be something of a blind alley.

One point I don't see mentioned here that I personally find significant... Many 4k TV's have built-in software to up convert a full HD picture to "NEAR 4K". However they must originate from a 1080p source. Many cable boxes are only capable of producing a 1080i picture. Just another consideration I felt compelled to add.CDEricson

Set the 3D TV display size.

Set the system to match the size of the screen of the TV you are using.

If the TV you are using is not a 3D TV, or if you did not select [HDMI] in step 4, this screen will not be displayed.

Set the resolution.

Select all resolutions supported by the TV in use. Video will automatically be output at the highest resolution possible for the content you are playing from among the selected resolutions.*

* The video resolution is selected in order of priority as follows: 1080p > 1080i > 720p > 480p/576p > Standard (NTSC:480i/PAL:576i).

If [Composite / S Video] is selected in step 4, the screen for selecting resolutions will not be displayed.

If [HDMI] is selected, you can also select to automatically adjust the resolution (the HDMI device must be turned on). In this case, the screen for selecting resolutions will not be displayed.

Set the TV type.

Select the type of TV in use. Set when only SD resolution (NTSC:480p / 480i, PAL: 576p / 576i) is to be output such as when [Composite / S Video] or [AV MULTI / SCART] is selected in step 4.

1080p (1920 1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen vertically;[1] the p stands for progressive scan, i.e. non-interlaced. The term usually assumes a widescreen aspect ratio of 16:9, implying a resolution of 2.1 megapixels. It is often marketed as Full HD or FHD, to contrast 1080p with 720p resolution screens. Although 1080p is sometimes referred to as 2K resolution[2][3][4] (meaning having a horizontal resolution of approximately 2,000 pixels[5]), other sources differentiate between 1080p and (true) 2K resolution.

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