Talk:Pixel aspect ratio

message: Aspect ratios may not be a perfect 1:1
http://www.mir.com/DMG/aspect.html
The difference is probably unimportant, unless you are (for example) supersampling. Still, anyone who actually understands PAR is welcome to update this :-) I would probably make it worse with accidental errors.
:Updated! Fleet Command (talk) 06:10, 17 November 2008 (UTC)
thread_title:  (Untitled) 

message: When the article says "square grid of pixels", it looks like the number of pixels in the horizontal direction should be equal to the number of pixels in the vertical direction. So a 640x480 image would not qualify. However, a 640x480 image can and usually does have square pixels.
Instead of "square grid of pixels", shouldn't we say "grid of square pixels"?
Also, when the article says "an NTSC picture (480i) with 1000 lines of horizontal resolution", shouldn't it be "an NTSC picture (480i) with 1000 columns of horizontal resolution" - Jorge Peixoto (talk)
:I believe this issue is resolved now.Fleet Command (talk) 06:32, 15 November 2008 (UTC)
thread_title: Confusing

message: This page should continually refer to "pixel aspect ratio" and "picture aspect ratio" to avoid any possible confusion when just saying "aspect ratio".
-Rob  —Preceding unsigned comment added by 122.29.39.122 (talk) 10:18, 19 June 2008 (UTC)
replies: text: I believe the new article now suits your need.Fleet Command (talk) 13:48, 12 November 2008 (UTC)

text: Personally, I believe you are right. But I didn't find a credible source that explains this in details in a NPOV manner. Most sources used for this article explicitly claim that HD standards define only square pixels. (See for yourself!) If you have a credible source that states otherwise, please let us know. Fleet Command (talk) 15:53, 1 April 2009 (UTC)
thread_title: Terminology

message: What if NTSC signals have a higher horizontal resolution because our eyes have a higher horizontal resolution?
:NTSC signals have the same horizontal resolution as vertical resolution.  See the wikipedia page for Kell factor.146.115.72.215 (talk) 02:22, 18 March 2015 (UTC)
thread_title:  Human optic nerve non-square resolution ratio 

message: What a mess. What an inconsistent, amateurish mess. Look folks. This is pretty easy stuff. Let's get it right.
Nothing has SAR = 704:480 because nothing stores 704 pix/line. An "NTSC" DVD (that is, a region-1 DVD) has SAR = 720:480 = 3:2, and a "PAL" DVD (that is, a region-2 DVD) has SAR = 720:576 = 5:4, but no storage media in existence has 704 pix/line. Consequently, PAR = 10:11 is useless. Forget it. It's just confusing things. That whole section dealing with 704 pix/line is nonsense. I know that some people think it's meaningful. Well, it isn't.
An image with DAR = 4:3 (that is, an SDTV image) stored on an "NTSC" DVD (SAR = 3:2), will, as a mathematical construct, have a PAR = DAR/SAR = (4:3)/(3:2) = 8:9. That PAR applies only to "NTSC" DVDs intended to be displayed on SDTVs. The "PAL" DVD equivalent is PAR = (4:3)/(5:4) = 16:15.
An image with DAR = 16:9 (this image unfortunately has no name -- I will call it "16:9-TV") stored on an "NTSC" DVD (SAR = 3:2), will, as a mathematical construct, have a PAR = DAR/SAR = (16:9)/(3:2) = 32:27. That PAR applies only to "NTSC" DVDs intended to be displayed on 16:9-TVs. The "PAL" DVD equivalent is PAR = (16:9)/(5:4) = 64:45.
There are just no other PARs worth talking about.
The pictures of 1:1 pixels and 2:1 pixels is wrong, wrong, wrong. PAR is NOT something you can see. What you see is display pels (not pixels). Pels are almost always square. PAR is a mathematical conversion ratio. Dump the pictures. They are misleading.
Here's how I explain PAR to a novice: When you telecine a 4:3, 35mm film frame (0.995 x 0.744 inches, which is a wide open, 35mm camera gate) for storage as 720 pix/line x 480 lines/frame (i.e., an "NTSC" DVD), the sample aperture should be approximately 0.001382 x 0.00155 inches -- calculated by simple division. That ratio is approximately 8:9. In other words, the sample aperture should be slightly thin (so as to get 720 samples per line instead of 640 samples per line). But when you telecine a 16:9, 35mm film frame (0.995 x 0.560 inches, a 35mm camera gate with height masked), the sample aperture should be approximately 0.001382 x 0.001166 inches -- same width, but much less height. That ratio is 32:27. In other words, the sample aperture should be reduced in height (so as to get 480 lines out of the squatter image frame). So you see, PAR is the proportions of the telecine's sampling aperture. Pictures of that sampling aperture might be helpful, but the pictures shown in the article are display pels, and that's just plain wrong.
Note how explaining film telecine aperture makes PAR understandable. But that 704 pixel stuff is just silliness. It was cooked up by people who thought that digital video resolution had something to do with analog luma bandwidth. Banish such thoughts. ...Yeah, yeah, I've read all the articles. But overscan is not an issue. Old video conversion hardware/firmware is not an issue. That's all old baggage ...And you know what? It never really was correct. --MarkFilipak (talk) 06:07, 24 August 2015 (UTC)
replies: text: Bottom line: You're trying to tell us that nothing happens if you change the aspect ratio between 1:1, 5:4, and 4:3 in VLC player, or at least "nothing that you can see". If that was true, we wouldn't need concepts such as PAR and DAR. But it's a fact that we do because video pixels are usually not square, particularly not when it comes to SD video. And no, not only analogue SD video, since DV, D1, etc. are also non-square, as neither 720x576 nor 720x480 make up a 4:3 image. None of this has anything to do with the telecine of film footage (by which you're only massively overcomplicating things and not helping any novice in the slightest), but rather with the fact that analogue SD video had non-square samples, a property which was deliberately imitated when digital video was invented in order to maintain that 1 sample = 1 pixel. Plus, there never was a "16:9 35mm film frame". While 16:9 equals 1:1.77777..., there only were certain widescreen formats such as 1:1.66 and 1:1.85 (which never really matched 16:9 to begin with), which were achieved by a variety of means, including anamorphic squeeze, matting, or actually manufacturing film with that aspect ratio. --2003:71:4F05:5035:1411:6FF0:8DE6:C730 (talk) 08:09, 3 June 2018 (UTC)
thread_title:  This subject is so bollixed I fear it will never be right. 

message: Heyyyy! What's going on with PAL's sampling? Is there 704 or 702???
Thank you! 2A01:E0A:AB0:C580:A4D1:6A9B:505:930 (talk) 16:54, 13 March 2023 (UTC)
thread_title:  PAL, 704 or 702??? Help me!