[opendtv] Display oversampling

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: OpenDTV Mail List <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 20 Sep 2011 11:29:37 -0400

Every once in awhile something happens to challenge one's perception of "good enough."

For the past two decades I've staunchly defended the 720P HD format, mostly because it was the only ATSC/MPEG2 format that uses progressive scanning at high frame rates. I also have been eager to point out that for most of the HDTV displays sold today ( i.e. under 50 inch diagonal), 1080P cannot be resolved by the typical viewer at the viewing distances found in most homes.

Then I got an iPhone 4 with its 326 dpi "Retina Display." While it this is clearly more resolution then my aging eyes can resolve, I can see a big difference, even without my reading glasses. Where it REALLY makes a difference is with text and graphics; it also helps with still images, and to a lesser extent with video.

What's up here, and how might much higher resolution displays affect the future of the movie and TV business and "convergence applications" on the "BIG SCREEN" in the family room?

There are two trends worth noting:

1. Hollywood has been all ga ga about 4K resolution, both for acquisition and for Digital Cinema display. 4K capture is still technically limited because of sensors and frame rate constraints; this continues to be the Achilles heel of video acquisition, based on something quite simple - physics and the ability to capture photons at higher frame rates in real time.

2. Displays have been moving forward at a pace that is more akin to Moore's Law; the move to LED backlighting has had a major impact thanks to the ability to handle much higher refresh rates. Meanwhile pixel densities have been increasing and the processing power required to handle the computational complexity of compressing and moving 4K images around has been keeping pace.

If we cannot resolve all these pixels, and video cameras still struggle to capture them, what are we to do with these new higher resolution displays?

The iPhone provides some good clues. Better yet, desktop publishing gave us part of the answer in the '80s. The Laserwriter taught us that we need more pixels to render text without aliasing along the edges; 300 DPI became the standard for a nice letter and digital pre-press, with several thousand DPI being used for high quality 4 color separations.

The extra resolution of the Retinal display makes a big difference when working with text and web pages. The main factor here is that the images are NOT moving - we have time to resolve the detail. With video there is only so much information that can be resolved when images are being updated 24 to 72 times a second; more detail is primarily required for VERY LARGE displays, such as those found in theaters.

So it appears we are moving to a new generation of "Oversampling Displays," with more resolution than is needed for movies and video. But these displays will also support a greatly improved viewing experience for the new APPS that are going to fill our computer and TV screens.

The following article provides some insight about all of this with respect to the next generation of chips from Intel; it also provides some explanation as to why the Thunderbolt interface is going to be needed to deal with next generation displays.



Tuesday, September 20, 2011
Intel's Ivy Bridge support for 4K resolution could pave way for 'Retina' Macs
By Josh Ong
Published: 01:18 AM EST (10:18 PM PST)

Intel quietly revealed last week that its next-generation Ivy Bridge processors will support the 4K display resolution, with up to 4096 x 4096 pixels per monitor, potentially paving the way for Apple to introduce high-resolution "Retina Display" Macs.

The world's largest chipmaker announced the news during a technical session at its Intel Developer Forum in San Francisco last week, as noted by VR-Zone. Ivy Bridge chips will rival competing discrete GPUs by including support for the 4K resolution when they arrive next year.

The company also highlighted a Multi Format Codec (MFX) engine that is capable of playing multiple 4K videos at once. The codec is also capable of handling video processing for 4K QuadHD video, a standard that YouTube began supporting last year.

A set of performance enhancements, with special attention to graphics, should give Ivy Bridge as much as a 60 percent performance boost over the current generation of Sandy Bridge chips, according to Intel.

Intel also revealed last week that Ivy Bridge chips will include support for Apple's OpenCL standard, which should give a performance boost to next-generation MacBook Air and 13-inch MacBook Pro models when they arrive in 2012.

If Apple were to introduce a 4K resolution display with the 16:9 ratio currently used in its Thunderbolt Display, iMac and MacBook Air products, the resulting resolution would be 4096 x 2304. A 27-inch display with 4K resolution would sport a pixel density of 174 pixels per inch. Assuming a working distance of 24 inches and 20/20 vision for the calculations, a 4K 27-inch iMac or Thunderbolt display would count as a "Retina Display."

Apple first began using the "Retina Display" marketing term with the iPhone 4 last year. Then CEO Steve Jobs touted the 326ppi display as being beyond the capabilities of the human retina when used at a distance of 12 or more inches from the eyes.

In September 2010, the company released a Retina Display iPod touch. Rumors have also swirled that Apple will follow suit with a high-resolution version of the third-generation iPad, doubling the resolution of the tablet to 2048 x 1536.

Of course, Macs that take full advantage of the 4K resolution capabilities built into future generations of Intel's chips would take some time to arrive, as Apple will need to resolve price and production constraints before releasing a Retina Display desktop or notebook. But, 3200 x 2000 desktop wallpapers were discovered in a Developer Preview of Mac OS X Lion earlier this year and appear to telegraph a future resolution bump for Apple's line of Mac computers.

Also of note, Apple added 4K support to its Final Cut Pro video editing program when it released version X in June. However, Final Cut Pro X has caused a controversy, as some users have complained that the application is no longer "pro" software.

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