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Old 2007-12-31, 03:15   #1
jasong
 
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Default video compression chatter by jasong

I was discussing compression with a friend of mine and I got to thinking.

Black and white pictures, and I guess video, compress a lot better than color ones. So what would happen if the video were split into 3 streams, red, yellow, and blue, and those streams were compressed the same as black and white video? I'm not sure how feasible that is from a programming standpoint, it might be a nightmare. Plus you need to be able to stitch them back together in a way that isn't hard for the end user to implement.

But wouldn't the compression ratio improve dramatically?
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Old 2007-12-31, 05:10   #2
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1. jpeg compression for pictures already implement a similar idea.

2. Decades of research have already been done on video compression research, so I am sure that this concept is already incorporated there.
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Old 2007-12-31, 05:35   #3
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jasong: You can try this link, it has all sorts of info about what you are referring to.
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Old 2007-12-31, 07:34   #4
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Quote:
Originally Posted by jasong View Post
I was discussing compression with a friend of mine and I got to thinking.

Black and white pictures, and I guess video, compress a lot better than color ones. So what would happen if the video were split into 3 streams, red, yellow, and blue, and those streams were compressed the same as black and white video? I'm not sure how feasible that is from a programming standpoint, it might be a nightmare. Plus you need to be able to stitch them back together in a way that isn't hard for the end user to implement.

But wouldn't the compression ratio improve dramatically?
Questions like this tempt my inner Silverman. In fact, the more I think about it, the more I'm offended by this question.
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Old 2007-12-31, 09:16   #5
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Quote:
Originally Posted by jasong View Post
Black and white pictures, and I guess video, compress a lot better than color ones. So what would happen if the video were split into 3 streams, red, yellow, and blue, and those streams were compressed the same as black and white video?
The primary colors are red GREEN and blue. Why should doing this make
compressing color images any less than three times as bulky
as black and white?
In fact they use "Yuv" which are linear combinations of RGB,
suited to the way the eye works. Y contains the "grey scale"
information, and u,v the color. In practice jpegs need less
bandwidth for the u and v than they do for the Y

Quote:
I'm not sure how feasible that is from a programming standpoint, it might be a nightmare. Plus you need to be able to stitch them back together in a way that isn't hard for the end user to implement.
Having written jpeg decompressors, I can assure you that splitting
and recombining the three streams is a completely trivial aspect of
the task!

David

PS that was my "UnSilverman" answer;)

Last fiddled with by davieddy on 2007-12-31 at 09:40
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Old 2007-12-31, 10:41   #6
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A further thought. If 24 bit color means 8 bits each
of red green and blue, why should compressing N 24-bit numbers
be any less compact than 3N 8-bit numbers?
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Old 2007-12-31, 11:17   #7
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Quote:
Originally Posted by davieddy View Post
A further thought. If 24 bit color means 8 bits each
of red green and blue, why should compressing N 24-bit numbers
be any less compact than 3N 8-bit numbers?
It's not, I think the OP never bothered to check any of the gozillions of websites that are available on the subject.
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Old 2007-12-31, 15:38   #8
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In case you jerks(I'm specifically thinking of retina and Orgasmic Troll) haven't thought about it:

When you combine red, yellow and blue colors together, the data appears more random than if you split it up into it's various components, so there's more potential for compression with the second method.
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Old 2007-12-31, 15:53   #9
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Quote:
Originally Posted by davieddy View Post
The primary colors are red GREEN and blue.
Maybe things work differently for televisions and other displays, but the basic colors are red, YELLOW and blue. Btw, yellow and blue make green.

Edit: I looked it up, and apparently things have changed over the years, so I'm right from a 1980s standpoint and you're right from a modern standpoint, which amounts to you winning.

Last fiddled with by jasong on 2007-12-31 at 16:02
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Old 2007-12-31, 15:55   #10
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Quote:
Originally Posted by jasong View Post
Maybe things work differently for televisions and other displays, but the basic colors are red, YELLOW and blue. Btw, yellow and blue make green.
That is so wrong that it is funny :D
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Old 2007-12-31, 16:19   #11
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:) <--- This "mood" applies to the rest of this particular post.

I know some of you are thinking,"If this method is better, than why isn't it used?" Well, ask yourself why BetaMax didn't become the dominant standard for VCRs, it was better according to everything I've read about it.

According to my reference(it was a private conversation and I didn't specifically ask if I could use him as a reference. I will, if it becomes an issue) the improved compression would be approximately 50:1. Now think what that would do for things like BitTorrent and you may begin to understand a possible reason this method isn't encouraged. Think how many movies(HD even) could be stored on a DVD if movies were 1/50th the size.
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