[Tig] artifacts

[Bob Friesenhahn]

On Tue, 23 Jan 2007, Greg D. wrote:
> Here's some Sony propaganda (?) regarding "artifacts:"

[ stuff removed ]

> What do you engineers out there make of the "...virtually free from motion
> artifacts??"

Sounds like more product sold.  Alchemy is the practice of converting 
lead to gold.

> How does this relate to the source material??  Can they in anyway actually
> make up for bad DVD authoring/encoding/compression work/technique?  Anyone
> believe this is doing anything positive?

It sounds like a filter that understands MPEG block noise and adds 
additional noise to hide the MPEG block noise.  Sometimes this noise 
may approximate the image that should have been there.  Algolith 
(http://www.algolith.com/) has specialized in this type of filtering 
for several years.

> On a related note, do folks believe in "up converting" DVDs to 1080 etc. at
> the player as most now offer?  or just watch em in 480P on your big HD
> screen.  Or maybe even just output in 480i and "rely on" for these and other
> 480i sources (in Sony's case like my SXRD TV) the tv to do the reverse 3:2
> and/or "up-rezing"/enhancing via the tv's hardware/software like DRC & other
> voodoo??  My Sony TV even lets you customize the ratio of detail (they call
> it Reality) to smear (they call it Clarity).

This is a recent fad.  The reality is that it depends on which 
component does a better job of handling pulldown, antialiasing, and 
scaling.  If you have a cheap TV, then maybe the DVD player will do a 
better job.  If you have a well designed TV, then maybe passing 480i 
will provide better results.  While one may assume that the DVD player 
has more data to work with, I don't think that this is really true, 
and there is an advantage of doing the processing in the TV since the 
TV may be able to offer the processed image with more bits and it 
understands its internal nuances (e.g. actual video line refresh rate, 
and actual raster image size).  People with money can purchase a 
separate video processor box which may do a better job than the DVD 
player or the TV can do.

> I noticed the other day that my Sony DVD player which I was having
> "up-convert" to 480P, caused the picture to stutter badly on pans and text
> even flickered back and forth btwn jaggies and ok.  The TV was probably
> adding its DRC stuff too.  I also wondered if the issue was related to the
> source material being originated and posted in HD "video".  It was a Henson
> Kermit the Frog movie from 2002.  I also now wonder if it was the reverse
> 3:2 getting goofed up because it was video originally??

Yes, this is a common problem, particularly when the DVD has been 
mastered incorrectly so it uses the wrong pulldown flag.  There is no 
correct way to deal with video-sourced material, but it is clearly 
wrong to apply 2:3 pulldown processing to video-sourced material.

Bob
======================================
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/