It is currently Thu Jan 28, 2021 4:56 am

All times are UTC




Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 97 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7  Next
Author Message
 Post subject:
PostPosted: Tue Aug 04, 2009 6:32 pm 
Offline
Obduction Backer

Joined: Tue May 09, 2006 2:00 am
Posts: 1669
Location: Lakewood, WA
aspect ratios & resolutions

Image


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 04, 2009 6:36 pm 
Offline

Joined: Tue May 09, 2006 9:16 pm
Posts: 367
Location: Montana
Rusty_Russell wrote:
No. Scaling is only the same if both x and y are the same. The operation is (4:3)(4:3).


Scaling is when both x and y are multiplied/divided by the same factor. ie 4x2:3x2 = 8:6 = 1.33:1

Put another way:
Code:
   4:3      8:6      12:9       16:9       16:12        20:15
1.33:1   1.33:1    1.33:1     1.78:1      1.33:1       1.33:1


Gee, which one is the odd one out??
16:9 is most definitely not equivalent to 4:3

Edit:
Oh, yeah. Thanks H!

Scaling is when all elements of a vector are multiplied by the same scalar.

_________________
Through space and time; along the threads of the stars; we seek the knowledge and wisdom of the ages.


Last edited by Teedyo on Tue Aug 04, 2009 7:01 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 04, 2009 6:41 pm 
Offline

Joined: Wed Nov 08, 2006 5:45 pm
Posts: 2553
Rusty_Russell wrote:
I've found a way to explain how I'm looking at this.

Scaling is a matrix operation - you're multiplying a row vector by a row vector - [4 3] * [4 3] = [16 9].

"made easier by the simple 4:3 aspect ratio between 4:3 and 16:9 (16:9 = 4:3 × 4:3)." - quoted earlier.


Except that's not how matrix multiplication works at all. You can multiply a vector by a scalar, ie 2 * [4 3] = [8 6], but multiplying two vectors gives you a matrix. Furthermore, you can't multiply two row vectors like that; you need a row vector and a column vector like this:
Code:
[4 3]*|4| = |16 12|
      |3|   |12  9|


Which is not an aspect ratio.

_________________
Nothing to see here, move along.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 04, 2009 7:28 pm 
Offline
Obduction Backer

Joined: Thu May 25, 2006 12:55 pm
Posts: 9852
Location: Luton, UK
Teedyo wrote:
Rusty_Russell wrote:
No. Scaling is only the same if both x and y are the same. The operation is (4:3)(4:3).


Scaling is when both x and y are multiplied/divided by the same factor. ie 4x2:3x2 = 8:6 = 1.33:1

Put another way:
Code:
   4:3      8:6      12:9       16:9       16:12        20:15
1.33:1   1.33:1    1.33:1     1.78:1      1.33:1       1.33:1


Gee, which one is the odd one out??
16:9 is most definitely not equivalent to 4:3


Quote:
I'm also aware that the true ratios are different - 1:1.33 (4:3) is not the same as 1:1.77 (16:9).


All I'm trying to do now is get from 4:3 to 16:9 using 4:3 - and failing. Matrices doesn't work because of the dot product.

I'll stick with my tiles. :)


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 04, 2009 11:27 pm 
Offline

Joined: Tue May 15, 2007 10:43 pm
Posts: 13
Wow, this is hilarious! This thread has turned into a seriously passionate discussion!!


Last edited by Skylark on Tue Aug 04, 2009 11:37 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 04, 2009 11:33 pm 
Offline

Joined: Tue May 15, 2007 10:43 pm
Posts: 13
vidroth wrote:
And I agree with everyone, while we wait for OSMOULNEXT or whatever we're calling it, it would be very nice to get a native widescreen mode hacked into UruCC.


Man, I would love to see this put to vote.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 05, 2009 8:53 pm 
Offline
Obduction Backer

Joined: Tue Oct 03, 2006 3:25 am
Posts: 869
I'll approach from a different angle, and appeal to external expertise:

The entire A/V industry says 4:3 is "standard" and 16:9 is "widescreen." Every store you go into, sells TVs of both kinds, and they're not shaped at all the same. Every electronics discussion you read draws a distinction between 4:3 and 16:9, never ever using them interchangeably. Use Occam's razor... is the likely explanation that you're right and the entire rest of the electronics world is wrong?

One more different test: what are the classic "4:3" resolutions?

640x480
800x600
1024x768
1600x1200

All of these have two things in common:

1) they all scale 4:3 by the same number:
160: 4x160 (640) : 3x160 (480)
200: 4x200 (800) : 3x200 (600)
256: 4x256 (1024) : 3x256 (768)
400: 4x400 (1600) : 3x400 (1200)

2) They all fit correctly on an old, non-widescreen monitor, and incorrectly on a new widescreen monitor--they stretch.

What are the typical "16:9" resolutions?

1280x720 (HDTV 720p/i)
1920x1080 (HDTV 1080p/i)

80: 16x80 (1280) : 9x80 (720)
120: 16x120 (1920) : 9x120 (1080)

And they only fit correctly on widescreen monitors.

Truth: if you scale with a different multiplier for your vertical than you do for your horizontal, you change the aspect ratio. Actually that is the definition of changing aspect ratios, to scale the vertical by a different number than the horizontal!

_________________
"I visited Esher's lab and all I got was this lousy t-shirt."
VidRoth -- KI#50637


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 05, 2009 10:11 pm 
Offline
Obduction Backer

Joined: Tue May 09, 2006 4:33 pm
Posts: 878
Location: Jurupa Valley, CA USA
You don't need linear algebra to simplify a fraction.

_________________
MOULa KI #32712
MOULa KI #23298
MOUL KI #35129
D'mala KI #74265
Gehn KI #10113


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 4:48 am 
Offline

Joined: Sat Nov 11, 2006 2:28 am
Posts: 687
Location: Bevin Field Office - KI: 01350736
Vidroth, there's less trouble here than you might think.

My laptop's graphics hardware is smart enough to pillarbox (i.e. letterboxing turned 90 degrees, on the left and right sides) 1600x1200 so it fits on the 1920x1200 screen.

And, speaking of 1920x1200, most graphics adapters nowadays are able to output 16:10, the "standard" laptop widescreen format, just fine.

But the most important question is...

Image

Can we watch The Bat Whispers in its original aspect ratio yet? :D

(The only problem posed by different resolutions is in adjusting the FOV, since everything else is already scaled, as the Bioshock scandal demonstrated.)


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 12:03 pm 
Offline
Obduction Backer

Joined: Thu May 25, 2006 12:55 pm
Posts: 9852
Location: Luton, UK
You want simple. 16 * 9 had to be derived from something - and it's not related to 4 * 3 by chance.

I know you can't see a 4:3 picture without stretching x on a 16:9 monitor - you're not applying a scalar function.

I'm not saying they're the same, I'm saying they're related.

This isn't just me. wikipedia.

Quote:
before sending the image to the TV, made easier by the simple 4:3 aspect ratio between 4:3 and 16:9 (16:9 = 4:3 × 4:3).


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 2:22 pm 
Offline

Joined: Tue Jun 23, 2009 2:49 pm
Posts: 103
Location: Colorado
Sorry, that line's gibberish to me. I had noticed that 16 = 4^2 and 9 = 3^2, but most visual media format standards tend to be fairly arbitrary(which is why you get such things as 35mm film and rolls of... what was it, 13 and 27 photographs?)

In any case, I don't put much weight by the argument of someone who screwed up not only matrix multiplication, but fractional multiplication and simple scale by such an extent. At this point, you're just trying to save face. Just admit you goofed and we can all get on with it.

[edit]Upon looking back and seeing just how badly Rusty_Russel screwed up his math, I must conclude that he is either 16, a literary student, or both. We were all stupid at 16.

16:9 != 4:3. Or more accurately, 16/9 != 4/3, since ratios are simply fractions with a : instead of a /[/edit]


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 3:17 pm 
Offline
Obduction Backer

Joined: Thu May 25, 2006 12:55 pm
Posts: 9852
Location: Luton, UK
Tell me where I goofed and didn't admit to it.

I've been trying to dig myself out of a hole with the wrong shovel and should have heeded the advice to stop digging. :)

I'm just trying (and failing) to explain what to me is blindingly obvious to people who don't see things the same way (apart from the author of the gibberish).

16:9 is an aspect ratio - 16 units in x by 9 units in y. It isn't just a fraction.

Yes, 16:9 isn't 4:3. It's 4:3 with a transform applied to it.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 4:21 pm 
Offline
Obduction Backer

Joined: Wed May 10, 2006 6:18 pm
Posts: 353
Location: 127.0.0.1/0.0.0.0
You are taking the width and height independantly while you should take them together or else you could also say that both 4:3 and 16:9 are related to 2:1 and to 1:1.

4:3 is "4:3" because it's simpler than 1.333333333333333333333333333333333333333333333333333333333333...:1
16:9 is "16:9" because it's simpler than 1.777777777777777777777777777777777777777777777777777777777777...:1

_________________
No, I'm not real95


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 4:35 pm 
Offline

Joined: Wed Nov 08, 2006 5:45 pm
Posts: 2553
Rusty_Russell wrote:
You want simple. 16 * 9 had to be derived from something - and it's not related to 4 * 3 by chance.

I know you can't see a 4:3 picture without stretching x on a 16:9 monitor - you're not applying a scalar function.

I'm not saying they're the same, I'm saying they're related.

This isn't just me. wikipedia.

Quote:
before sending the image to the TV, made easier by the simple 4:3 aspect ratio between 4:3 and 16:9 (16:9 = 4:3 × 4:3).


Your quote is referring to anamorphic widescreen which is a method of fitting 16:9 images into a space meant for 4:3 images.

A more relevant Wikipedia section is this one: http://en.wikipedia.org/wiki/16:9#Why_16:9.3F
Quote:
When the 16:9 aspect ratio was proposed by Kerns H. Powers, nobody was creating 16:9 videos. The popular choices in 1980 were 4:3 (based on television standard's ratio at the time), 1.66:1 (the European "flat" ratio), 1.85:1 (the American "flat" ratio), 2.20:1 (the ratio of 70 mm films) and 2.39:1 (the ratio of anamorphic widescreen films). Powers discovered that all of those aspects when normalised to constant area would fit within an outer rectangle and when over-lapped, all shared a common inner rectangle. The aspect ratio of these rectangles is simply the geometric mean of the extremes of 4:3 and 2.39:1, that is, 1.77:1, which is coincidentally close to 16:9, or 1.78:1.


16:9 is "related" to 4:3 in that, as you said, a 16:9 image can be built out of 4:3 tiles, but 16:9 was not derived (directly) from 4:3; it was created as a compromise between all the aspect ratios being used at the time and was determined mathematically. (This is explained in a bit more detail on page 8 of this PDF.) It is just a mathematical coincidence that 16:9 can be related to 4:3 in that way.

_________________
Nothing to see here, move along.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 06, 2009 5:11 pm 
Offline
Obduction Backer

Joined: Thu May 25, 2006 12:55 pm
Posts: 9852
Location: Luton, UK
Ok. I don't believe in mathematical coincidence when there's a second example. 16:10 is a manipulation of the 5:4 aspect ratio (also visible with tiles).

realXCV, 4:3 is overloaded - it isn't just 4/3 it's 4x by 3y. To treat it as a fraction is to ignore it as a ratio.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 97 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7  Next

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron