Having a Senior Moment: Non-Square Pixel Rendering

Gra · Post by **Gra** » Sat Dec 20, 2008 5:01 pm

Hi Guys
I've been a bit immersed in a new home for the last few months (kind of a little bit more building than anticipated) and I'm quickly putting together a short movie but my minds gone blank. Do I check 'Perform non-square pixel rendering' for output to TV or only if my presentation is destined for a PC monitor???

I know this is daft and I am sorry to ask such an obvious question but I went through the forim search and I got myself even more up a gum tree: I think age has struck!

Post by **Ron P.** » Sat Dec 20, 2008 5:06 pm

Hi Gra...

Non-square pixels refer to most TVs, whereas PC monitors AND some of the newer HD TVs (plasma, LCD) use square pixels. So if your TV is not like a PC monitor you would want to render non-square pixels..

sjj1805 · Post by **sjj1805** » Sat Dec 20, 2008 8:47 pm

Non Square Pixel Rendering.

I admit that this used to confuse me for quite a while until eventually the penny dropped - so let me explain it in laymans language.

Think of a screen size - any screen size will do, for arguments sake we will say that our screen size is 100 x 100.
If we use Square pixels then we will have a perfect 100 x 100 square like a sheet of graph paper.
If we use non square pixels then these pixels could be oblong in shape.
Therefore the 100 x 100 will not be square.

To clarify that even further lets put some sizes to those pixels.
Let us say that our square pixels are 1" x 1" (OK a pixel isn't an inch - I am just trying to make things clear)
so we have a 100 x 100 square measuring 100" x 100"

In our non square pixel example each pixel is 1" high x 2" wide
so now our 100 x 100 grid is in fact 100" x 200" (Oblong)

Both examples contain a 100 x 100 grid but in the square one it is "Square" - the non-square one is "Oblong".

Devil · Post by **Devil** » Sun Dec 21, 2008 7:50 am

And don't forget that SD is 768 pixels wide, even if you use only 704 or 720 of them. 768:576 is exactly 4:3, so if you use that aspect ratio, the pixels are always square. 768:480 is not 4:3, so the pixels are not square.

The question is with 16:9. With SD, the pixel ratio is exactly the same but the display system makes them anamorphic, so the 576i system still has square pixels.

So what of HD? In these, the pixels are never square, but I haven't a clue whether this is taken care of in the display system.

Gra · Post by **Gra** » Mon Dec 22, 2008 12:39 pm

Thanks, everyone, for your comments.

My project is 768:576 for viewing on PCs, so I don't need to check the 'Perform non-square...' then. I assume it is better set it as 'frame based' rather than the normal 'field' settings???

Devil · Post by **Devil** » Mon Dec 22, 2008 1:17 pm

I suppose so, but I don't think it will make any difference with LCD monitors because these display whole frames anyway, at 70-100 fps!

Gra · Post by **Gra** » Mon Dec 22, 2008 1:23 pm

Thanks D.