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-   -   quicktime photoJPEG 4:2:2 or 4:2:0? (https://www.dvinfo.net/forum/non-linear-editing-pc/49539-quicktime-photojpeg-4-2-2-4-2-0-a.html)

Miguel Lopez August 18th, 2005 08:59 AM

quicktime photoJPEG 4:2:2 or 4:2:0?
 
Hello.
Is the quicktime photoJPEG compression (at 100%quality) 4:2:2 or 4:2:0?

thanks!

Graeme Nattress August 18th, 2005 11:52 AM

Neither, at 100% it's RGB 4:4:4

At 75% it's Y'CbCr 4:2:2

Graeme

Miguel Lopez August 19th, 2005 08:34 AM

Thanks!
Then, if at 100% it s 4.4.4 where does the compression came from? becasuse file sizes are considerably much smaller than uncompressed images.

Miguel Lopez August 19th, 2005 01:16 PM

And why is that when i render the same file from after effects, instead of vegas (with same settings), the file size is more than twice?

Graeme Nattress August 19th, 2005 01:19 PM

About Vegas / AE, I have no idea.

The compression comes from quantising the discrete cosine transform coeficients - that's how JPEG works, and how it gives variable compression amounts. PhotoJPEG is a superb codec for high quality and small (relatively) sizes.

Graeme


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