HD1080i De-mystify HDTV 1080i ::: know why before you buy

Sunday, January 07, 2007

Full HD 1080



Shown above are the relative areas of screen resolution.
red is 1920 x 1080 16:9 FULL HD
gray is 1366 x 768
black is 1280 x 720
blue is 720 x 480

If all pixels were the same size, this would be the relationship of amount of equally detailed area. If you take an image that is fully detailed in the space of the blue box and stretch it out to fill the area enclosed by the gray border, then you are essentially doing the same thing as getting your face 3 times closer to the screen. This doesnt get you a better image, just the same thing bigger. New Technology is available and developing that actually can make the larger scaled-up image look rather nice, and in effect make you feel that you are seeing a higher resolution.

HD is where edges matter, details tell all.
Its very important, the ability of the human visual system to resolve details, like body language, that is present in anything they see. 1920 x 1080 pixels of resolution provides this detail where you are seeing the image in about the same detail that you see everything else, when spread out over 40-60" of area and that is average room size viewing distance to resolved detail.

The problems that need fixing are that Video and TV are images in motion... things change over time. It is here that Interlaced ( every other row sent separately ) content from broadcasts must be reassembled into a complete image. 1080i coming in, 1080p on the screen.

Le me show an example before describing the issues.

Mike's Bike Video



crop of Mikes bike video frame in 108o ppixel for pixel


Interlacing error is one pixel separation of horizontal ( odd / even ) lines, play with the flash example above, animated sliding to see what it really does in an image. Click "Normal" to see what is normal 1080i.

You may well have seen fleeting moments of such stuff on your screen where a comb like edge appears when something in the video is moving, and you also may recognize this as a horizontal effect. This comb look is always a left-right edge problem. In the above view, it only takes 4 pixels of purely horizontal panning shift to cause a horrible outcome when de-interlacing is not done properly. If everything is done right which is the usual case - you never see this.

It is this issue that makes de-interlacing and scaling firmware in your HDTV or set-top so important. Lots of very fast technology goes into this, read my other posts on DCDi. Each frame is de-interlaced prior to scaling inside the display's processing path, using Directional Correlation de-interlacing math. Very cool.

But it isnt that simple. Some broadcasters will actually scale up lower res video, not deinterlaced, and then send that out thru 1080i. Classic failure to attend to this detail of processing is not your fault, or the fault of your TV, it is created by the source provider ( telecine processing ) and the Cable/dish digital provider systems. TNT especially - thru Comcast, on shows like "Charmed" have digitized film in interlaced format, scaled that, and distributed.



Broadcast 1080i of a scene from King Kong.

Properly handled de-interlacing of a film broadcast in 1080i should look like this, where a motion blur in the direction of the motion is presented ( zoom up of a screen shot from King Kong ) 1/60th of a second. You can see a slight ghost of the plane's wings from the previous frame, and a line-blur from the tracer bullet it shoots. No Jaggy comb effect, broadcast properly. In 1080p you should see none of this slight ghost, but you need a 1080p source like HD-DVD or Blu-ray to get it.
I'm not going into 2:3 pulldown since that film-rate to ATSC broadcast rate is now handled really well by every player in the market.

1080p
Bly-ray and the HD-DVD in progressive formats, remove the need for processing of this type entirely, by providing an already cleaned up and exactly rendered image of what they want you to see in every frame., and do that at the source, your HDTV doesnt have to do anything more than just decode/de-encrypt and show it to you.

The value of 1080p? It is like a guarentee that the technology is available and in use to assure a perfect image in every frame. This doesnt mean the movie itself was great, detailed and clean, just that the technology is there to provide for it. I think Made for HD DVD, shot in 4k or HD ( not film conversions telecine or otherwize ) will really express this, and that has yet to become the normal production.

If you make an investment in 1080 native resolution display technology then you will get the value out of it from the Full Frame no-interlace processing inherent in 1080p from the high definition DVD.

I shoot in HD and "flatten" my videos at the point of color correction to be 1080 for this reason, most commonly for 24p since it lets me control the motion and feel of focus in foreground motion vs focus and depth of field in background motion blur. Lots of high action happens in sub-second time so the natural feel of a progressive frame requires managing this. It is so worth that step in processing. I now also rely on VC-1 to be my codec for archive.

OK SO WHAT DOES ALL THIS MEAN?

HD-DVD/ Blu-ray in VC-1 @ 1080p displayed on a real 1080p monitor is what HD is all about.

Almost everything else is "almost HD", very good, but not all there is. So all these so-called experts that do not have 1080p in front of them, that do not shoot in the format and edit in the format, just dont know what the f&@k they are talking about. These editorializers that claim to have authoritative understanding of things are interested in extending thier own importance than in actually knowing the reality first hand. I read an Article that basically said 1080i and 1080p are indistinguishable for most people. I disagree, a 1080p source is enough better to justify the HD-DVD and Blu-ray for its value. Scale that down to 720p and its still nice but you just cut your detail level down to 1/2 of what it should be. Kind of like buying a Camaro with a nice paintjob and having a 4 cylinder engine in it.

WHY VC-1? - because there is no scene-cut block recovery artifacts in it when its done really well, its perfect. Read Macroblock garbage is my worst complaint about mpeg2 and mpeg4.


CES - DUAL HD-DVD/Blu-ray play in one unit.
We should see some dual format media and players this year and i think its all good.


The Dual Format LG BH100 first generation player Retail $1200.
It plays everything you put into it. ALL DVDS any format.
Conversations by cell with attendees confirms its really a Blu-ray player and burner with the added capability of handling HD-DVD playback. All indications from those that i know that spent bucks on thier 1080p screens, failed to get a PS3 yet ... is unanimous. They want one. I would like to know first hand that the upscaling of std DVD widescreen versions is good on this unit but it looks like a win.

Interesting to note they do not list VC-1 as a format codec on the Best Buy site , instead they simply say SMPTE. I guess you are expected to relate that SMPTE 421M is the official Spec name, but you could sort of say that its WMV9 and be in the same class of codecs. I want the common term of understanding to be VC-1.

This player is a fully built computer, so inside there is processing for the BDJ stuff meaning interactive programming for Blu-ray, and an ethernet port for future networking, hopefully meaning you can upgrade the operating system in it, upgrade firmware, get "Soft" deliverable feature enhancements. Yep, i'm liking this.

When the Video-techygeek early adopters are done buying this, then the price will drop and some stripped down to basics equivalent will probably be built into a TV that i will probably buy, slap on my bedroom wall. thanks LG.

1 Comments:

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4:42 AM  

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