The key to all this to remember that digital TV pictures are wider than analogue.īut the 4×3 image (702 pixels wide) sits inside those 720 pixels.ĭigital TV pictures are wider than analogue – the 4×3 bit sits inside Television pixels aren't square Here’s the crucial part – digital TV pictures are wider So if we rewind a bit to the old analogue days – you can see from the diagram below that our TV set with its wider pixels is effectively only 702 pixels across. So when I talk about aspect ratios and pixel dimensions the vertical height is always 576 regardless.Ī square pixel device (like a computer) would need an image to be 768×576 to maintain a 4×3 aspect ratio.īut TV pixels are rectangular – instead of 1×1, they’re more like 1×1.094.
The following explanation assumes 576 visible TV lines (out of the total of 625). Oh, and before we get too bogged down, I’m talking about standard definition PAL here. Anyway, there’s a few resources out there that try to explain this (links included below) – but I thought I’d have a go myself. I can still remember when it was first explained to me many years ago when I was still at the BBC, and it’s the kind of thing that’s quite difficult to get your head around without drawing little pictures on the back of envelopes. Well, to begin with, it’s all a bit complicated. In CS3, compositions using that preset would be set to 1024 x 576 pixels. Seems the latest version of After Effects from Adobe (CS4) has changed the PAL D1/DV Widescreen square pixel preset.
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