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Re: Information, Compression, and storage.
- To: telecine at alegria.com
- Subject: Re: Information, Compression, and storage.
- From: "Paul Grace" <paul at firstart.co.uk>
- Date: Wed, 07 Jul 1999 11:07:14 +0100
- Resent-Date: Wed, 7 Jul 1999 05:29:41 -0500
- Resent-From: telecine at alegria.com
- Resent-Message-ID: <"7iRDxD.A.oaC.Rwyg3" at sun>
- Resent-Sender: telecine-request at alegria.com
- Resent-To: multiple recipients of <telecine at alegria.com>
> In round terms, that is 720 pixels on 480 lines 30 times a second in three
> colours (we'll live with 8 bits for the moment). Multiply that lot together
> and you get around 30 megabytes per second. If you are going to get it down
> to (for the purpose of this argument) 3 megabytes a second, you are
> throwing away 90% of that beautiful picture. Anyone think that is a good
I agree with the bulk of your mail.
As someone that works in the FX end of the business I too avoid lossy
compression whenever possible. I too push for greater bandwidth, resolution.
This is not based on subjective opinions on how much an image can be
compressed to look OK, but on results from keyers in compositing and colour
However, not all compression is lossy and there is a good argument for using
data compression if it is lossless for high end work.
As images enter the data world lossless encoding techniques such as run
length encoding RLE make sense.
A good application for this is in digital film work where it is not yet
fully real time. Images can be stored in say a compressed tiff format (just
like the print industry has been using this standard for years) and save
huge amounts of disk space at no detriment to the image and therefore speed
up the workflow of moving images around networks and archiving. This assumes
a linear file format is used.
Compression is not necessarily a dirty word, it is how the process is
adopted and applied.
I'm not sure your figure above actually equates as simply to "throwing away
90% of that beautiful picture" as in most compound compression schemes
there is a percentage of lossless algorithm. Certainly the image would be
severely degraded, aka crap, to us in the industry viewing on studio
monitors. But viewed on the small LCD screen on the back of an aircraft seat
it would probably look fab. Whether this is good enough in the home is
another subjective issue that the public will decide.
Thanks to Rich Torpey for support in 1999
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1047 subscribers in 41 countries on Wed Jul 7 05:29:37 CDT 1999
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