What is 1080i?

[The Lion King]

Excuse my laziness, ignorance and....stupidness, but what exactly is 1080i?

[Blu-ray Fanatic]

The "i" stands for "interlaced" and "p" is "progressive".

[bajor27]

1080i means 1080 interlaced lines of resolution.

basically what that means is that not all 1080 lines are shown at once. only 540 are shown at once and then the other 540 are shown right after.

Basically, it's like there are 1080 lines of pixels running across your screen from top to bottom. for 1080P, every line is shown at the same time. for 1080i, every other line odd numbered line is shown first (like lne 1, 3, 5, 7, etc), then every even numbered line (2, 4, 6, 8, etc). It's happening so fast that it's basically impossible to see. Motion can sometimes look funny though as it's not as fluid to only see every other line of the motion. It's kind of like only half of a person is moving slightly ahead/behind the other part.


And it could be even lines before odd, but it doesn't really make much difference.

[Homura]

Originally Posted by bajor27

1080i means 1080 interlaced lines of resolution.

basically what that means is that not all 1080 lines are shown at once. only 540 are shown at once and then the other 540 are shown right after.

Basically, it's like there are 1080 lines of pixels running across your screen from top to bottom. for 1080P, every line is shown at the same time. for 1080i, every other line odd numbered line is shown first (like lne 1, 3, 5, 7, etc), then every even numbered line (2, 4, 6, 8, etc). It's happening so fast that it's basically impossible to see. Motion can sometimes look funny though as it's not as fluid to only see every other line of the motion. It's kind of like only half of a person is moving slightly ahead/behind the other part.


And it could be even lines before odd, but it doesn't really make much difference.

best description i've read

[The Lion King]

Originally Posted by bajor27

1080i means 1080 interlaced lines of resolution.

basically what that means is that not all 1080 lines are shown at once. only 540 are shown at once and then the other 540 are shown right after.

Basically, it's like there are 1080 lines of pixels running across your screen from top to bottom. for 1080P, every line is shown at the same time. for 1080i, every other line odd numbered line is shown first (like lne 1, 3, 5, 7, etc), then every even numbered line (2, 4, 6, 8, etc). It's happening so fast that it's basically impossible to see. Motion can sometimes look funny though as it's not as fluid to only see every other line of the motion. It's kind of like only half of a person is moving slightly ahead/behind the other part.


And it could be even lines before odd, but it doesn't really make much difference.

Nice description, thanks.

Makes me wonder: why do they use it? Seems like 1080p is easily the way to go.

[Blu_Ray_Fan]

Originally Posted by The Lion King

Nice description, thanks.

Makes me wonder: why do they use it? Seems like 1080p is easily the way to go.

They really don't use it anymore... 1080p is the new standerd and it's great!

[Pelican170]

Originally Posted by bajor27

1080i means 1080 interlaced lines of resolution.

basically what that means is that not all 1080 lines are shown at once. only 540 are shown at once and then the other 540 are shown right after.

Basically, it's like there are 1080 lines of pixels running across your screen from top to bottom. for 1080P, every line is shown at the same time. for 1080i, every other line odd numbered line is shown first (like lne 1, 3, 5, 7, etc), then every even numbered line (2, 4, 6, 8, etc). It's happening so fast that it's basically impossible to see. Motion can sometimes look funny though as it's not as fluid to only see every other line of the motion. It's kind of like only half of a person is moving slightly ahead/behind the other part.


And it could be even lines before odd, but it doesn't really make much difference.

Good definition, im very glad to see that you explain the "its basically impossible to see", because its true. I hate when people try to justify that 1080i is the same as 540, cuz its totally false in my opinion.

[syncguy]

Above explanation is correct for CRT displays but not for digital displays such as plasma, LCD or projectors. The digital displays are always progressive display devices. They cannot display an interlaced image (in contrast to CRT displays).

In relation to digital displays 1080i means the way the picture is transmitted from the player (source) to the display device. As explained in the above post a frame is divided into two halves (if the original picture is 1080p like a blu-ray movie) and transmitted to the display device. The display reconstructs the frame (i.e. deinterlace) before displaying it on the digital progressive display.

I have heard that rarely there are interlaced digital displays. But these are exceptions.

[MPDIEHL]

The only thin I would like to add is about refrech rates.
The standard refresh rate has always been 60Hz..
60 times per second the info is sent to the screen to be redrawn.
with interlaced scaning you get the odd lines 30 times per second and the even lines 30 times per second.
With progressive scanning you get all 1080 lines 60 times per second.
Some newer higher end LCD sets now scan at 120Hz.
Same math holds true all 1080 lines 120 times per second.
This feature was added to help reduce the motion blur associated with LCD TV's.

[kalkin84]

Originally Posted by Blu_Ray_Fan

They really don't use it anymore... 1080p is the new standerd and it's great!

wrong. 1080p is nice, but only BD and computer outputs (other devices as well) output 1080p. the vast majority of broadcast HD (cable, sat, antenna) is 1080i with the remainder being 720p and, due to bandwidth requirements of 1080p, will remain so for the forseeable future.

you watch your movies (hopefully) and play your video games in 1080p, but all your HD TV reception however is 1080i/720p with the vast majority 1080i. It is, in fact, the most used HD resolution there is at this point. So go get a TV with a damn good deinterlacer.

[Beta Man]

Originally Posted by kalkin84

wrong. 1080p is nice, but only BD and computer outputs (other devices as well) output 1080p. the vast majority of broadcast HD (cable, sat, antenna) is 1080i with the remainder being 720p and, due to bandwidth requirements of 1080p, will remain so for the forseeable future.

you watch your movies (hopefully) and play your video games in 1080p, but all your HD TV reception however is 1080i/720p with the vast majority 1080i. It is, in fact, the most used HD resolution there is at this point. So go get a TV with a damn good deinterlacer.

Glad you pointed that out..... lots of bad info out there.... like people claiming there is a big difference in 720p and 1080p on a 32" when they sit 10 feet away...... they're just fooling themselves..... just like thinking their HD TV programming is 1080p !

[syncguy]

Originally Posted by Beta Man

Glad you pointed that out..... lots of bad info out there.... like people claiming there is a big difference in 720p and 1080p on a 32" when they sit 10 feet away...... they're just fooling themselves..... just like thinking their HD TV programming is 1080p !

They must have egale eyes.

However, if someone compares 1920x1080 set and 1280x720 set, say from 10 feet away, they may see a better picture on 1920x1080 set just because it is a better set. i.e. more contrast, more brightness, good scaler for DVD etc.

[dobyblue]

Originally Posted by Pelican170

Good definition, im very glad to see that you explain the "its basically impossible to see", because its true. I hate when people try to justify that 1080i is the same as 540, cuz its totally false in my opinion.

I think you're missing what people are incorrectly stating, people that say this don't understand resolution; they think that 1080i is 540p, when it's really 1080 lines of resolution and when de-interlaced properly will be 1080p.

However, when you have one of the many sets that fail deinterlacing tests, you can wind up with 540p from every odd or even line as the set may discard one or the other.

So you start with 1080i (first 6 lines represented here)

1
_2
3
_4
5
_6

A TV that deinterlaces properly will give you 1080p

1
2
3
4
5
6

But a TV that doesn't may give you what can only be described as a "doubled 540p"

1
1
3
3
5
5

In addition to this, if you have a plasma, DLP or LCD you can't WATCH 1080i anyway - all these panels are progressive displays and therefore will need to deinterlace the interlaced signal before they display it.

Originally Posted by kalkin84

wrong. 1080p is nice, but only BD and computer outputs (other devices as well) output 1080p. the vast majority of broadcast HD (cable, sat, antenna) is 1080i with the remainder being 720p and, due to bandwidth requirements of 1080p, will remain so for the forseeable future.

you watch your movies (hopefully) and play your video games in 1080p, but all your HD TV reception however is 1080i/720p with the vast majority 1080i. It is, in fact, the most used HD resolution there is at this point. So go get a TV with a damn good deinterlacer.

There is no difference in resolution between 1080i and 1080p, they're both identical. That is to say, they both contain 1080 lines of vertical information, the only difference is how they are delivered. Agreed on the last sentence though - it's vital for 1080i.

Everyone here should read this article to get a better understanding of 1080p and 1080i and also, why 1080p is important or getting a TV with good deinterlacing and 3:2 cadence is important as well.

1080p24 can be converted to 1080i60 and back to 1080p24 with ZERO loss of information when performed properly.

http://www.hometheaterhifi.com/volum...07-part-1.html

[syncguy]

1080p has more information than 1080i if both are at the same frame rate, say 60 per second. In case of 1080/60p it will be 60 frames per second but in case of 1080/60i it will be 60 half frames or fields.

If the source is 1080/60p (e.g. PS3 game), converting to 1080/60i will lose half frames and may introduce judder. In this case, a better way could be to downscale 1080/60p to 720/60p at the PS3 and then send 720p to a display that accepts 720p/1080i signal.

If the source is 1080/24p (e.g. blu-ray movie), converting to 1080/60i will not lose information and therefore it can be reconstructed (or deinterlaced) at the display without losing picture quality.

[Paganmoon]

Originally Posted by syncguy

1080p has more information than 1080i if both are at the same frame rate, say 60 per second. In case of 1080/60p it will be 60 frames per second but in case of 1080/60i it will be 60 half frames or fields.

If the source is 1080/60p (e.g. PS3 game), converting to 1080/60i will lose half frames and may introduce judder. In this case, a better way could be to downscale 1080/60p to 720/60p at the PS3 and then send 720p to a display that accepts 720p/1080i signal.

If the source is 1080/24p (e.g. blu-ray movie), converting to 1080/60i will not lose information and therefore it can be reconstructed (or deinterlaced) at the display without losing picture quality.

1080/24p converted to 1080/60i would result in judder too, would it not?

[syncguy]

It shouldn't if done correctly.

[U4K61]

Originally Posted by Paganmoon

1080/24p converted to 1080/60i would result in judder too, would it not?

Yes 1080i/60 has motion judder. However 1080i can be de-interlaced back to 1080p, and if we have a 120Hz set that provides intiger multiples of 24fps such as 24x5=120, we can view film based material juddr free. We can't divide 60 by 24 evenly so you will have non-integer 3:2 pulldown issues on a 60Hz set.

[dobyblue]

Unfortunately there are a number of 120Hz sets that will not do 5:5, they will do 3:2 and then 2:2, thus maintaining 3:2 judder.

1080i and 1080p at the same frame rate would yield the same information.

The number after the delivery method refers to fields, not frames.

[U4K61]

Originally Posted by dobyblue

Unfortunately there are a number of 120Hz sets that will not do 5:5, they will do 3:2 and then 2:2, thus maintaining 3:2 judder.

1080i and 1080p at the same frame rate would yield the same information.

The number after the delivery method refers to fields, not frames.

I guess I was sloppy on not putting 60x2 (30x2x2) along with 24x5 for cadence on 120hz sets.

I know 1080i/60 refers to 60 fields(30 frames), and 1080p/60 refers to 60 frames. Also 1080i sourced from 24fps film, we can de-interlaace and get back to 24p and then if the set is 120Hz, watch 5:5 24fps judder free

Great for 24fps film. But if it's 1080i from a video camera, a progressive set must determine which of the two it is getting, progressive or interlace, so it knows weather to bob or weave the image.

[welwynnick]

Originally Posted by syncguy

It shouldn't if done correctly.

Why shouldn't it?

The fields taken from successive frames have to be refreshed two times and three times respectively. That's what causes judder.

Nick