Convert 4:1:1 YUV data to RGB

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4 total messages Started by Soam Acharya Thu, 23 Jul 1992 21:16

#183

Author: Soam Acharya
Date: Thu, 23 Jul 1992 21:16

31 lines
1588 bytes

Greetings all,

Can anyone point me towards a reference that explains how to convert
4:1:1 subsampled YUV data to RGB? 

I'll be happy to provide more details if necessary.  I am planning on
using the Sun VideoPix board to implement some sort of rudimentary
moving picture capture/display facility and I'd rather not use the
Sun VideoPix software libraries for the sake of portability and
curiosity - I want to know how this image conversion is done.

Any help will be greatly appreciated

Soam

PS -	Before anyone asks, I've tried comp.graphics
	and comp.sys.sun.wanted, so far with no success.


---------------------------------------------------------------------------
   Soam Acharya					soam@ee.cornell.edu
   Eng. & Theory Center, #369			soam@cs.cornell.edu
   Cornell University				607-254-8811
   Ithaca, NY 14853
   
   "We are the goon squad and we're coming to town.
    Beep beep.
    Oo aa pa ra ra fa fa fa fa fashion."
				
				- David Bowie ( in his glory days )

Re: Convert 4:1:1 YUV data to RGB

#212

Author: Phil Jensen
Date: Mon, 27 Jul 1992 13:04

18 lines
968 bytes

In comp.multimedia, soam@freyja.cs.cornell.edu (Soam Acharya) writes:

> 
> Greetings all,
> 
> Can anyone point me towards a reference that explains how to convert
> 4:1:1 subsampled YUV data to RGB? 
> 

Call your local Signetics Rep and ask for the Phillips Video Data Handbook.
This contains specs on the parts that are on your board. Look at the SAA7192
Digital Colour Space Converter. This is a YUV to RGB converter. Included are 
equations for the YUV to RGB conversion.

---------------------
Phil Jensen
pej@hpfcpej.fc.hp.com
---------------------

Re: Convert 4:1:1 YUV data to RGB

#222

Author: Andrew Fitzhugh
Date: Wed, 29 Jul 1992 23:01

37 lines
1793 bytes

/ hplred:comp.multimedia / pej@hpfcso.FC.HP.COM (Phil Jensen) /  6:04 am  Jul 27, 1992 /
> In comp.multimedia, soam@freyja.cs.cornell.edu (Soam Acharya) writes:
> > Can anyone point me towards a reference that explains how to convert
> > 4:1:1 subsampled YUV data to RGB? 
> > 
> 
> Call your local Signetics Rep and ask for the Phillips Video Data Handbook.
> This contains specs on the parts that are on your board. Look at the SAA7192
> Digital Colour Space Converter. This is a YUV to RGB converter. Included are 
> equations for the YUV to RGB conversion.

Actually, the Signetics book gives the equations for YCbCr (normalized
YUV, so they're essentially the same).  I just happened to be typing
in these numbers so I can save you some time:

|R|   | 1.000  0.000  1.000 | |Y|
|G| = | 1.000 -0.186 -0.508 | |U|
|B|   | 1.000  1.000  0.000 | |V|

|Y|   | 0.299  0.587  0.114 | |R|
|U| = |-0.299 -0.587  0.866 | |G|
|V|   | 0.701 -0.587 -0.114 | |B|

And if you want to use YCbCr,

|Y |   |     Y     |
|Cb| = | 0.564 * U |
|Cr|   | 0.713 * V |

Benson's "Television Engineering Handbook" (ISBN 0-07-004779-0),
though poorly organized and containing plenty of typos, contains all
kinds of stuff like this.  It's a better general reference than the
Sig.  data book, but it's far from free (~$100, I think).

Andrew Fitzhugh
Computational Color Reproduction
HP Laboratories

Re: Convert 4:1:1 YUV data to RGB

#227

Author: David Berry
Date: Thu, 30 Jul 1992 17:26

42 lines
1961 bytes

In article <116780001@hplred.HP.COM> fitzhugh@hplred.HP.COM (Andrew Fitzhugh) writes:
>/ hplred:comp.multimedia / pej@hpfcso.FC.HP.COM (Phil Jensen) /  6:04 am  Jul 27, 1992 /
>> In comp.multimedia, soam@freyja.cs.cornell.edu (Soam Acharya) writes:
>> > Can anyone point me towards a reference that explains how to convert
>> > 4:1:1 subsampled YUV data to RGB? 
>> > 
>> 
>> Call your local Signetics Rep and ask for the Phillips Video Data Handbook.
>> This contains specs on the parts that are on your board. Look at the SAA7192
>> Digital Colour Space Converter. This is a YUV to RGB converter. Included are 
>> equations for the YUV to RGB conversion.
>
>Actually, the Signetics book gives the equations for YCbCr (normalized
>YUV, so they're essentially the same).  I just happened to be typing
>in these numbers so I can save you some time:
>

I sent mail to the original poster, the problem is that the chip set
used on the VideoPix hardware is the SAA9051. This is not compatible
with the YUV to RGB converter chip listed above. (If I am wrong
someone will hopefully correct me.)

The VideoPix equations, as given to me by Phillips for the SAA9051
are,

	/*
	 * Philips YUV to RGB. These
	 * aren't the same as standard YUV to RGB.
	 * The equations are
	 *
	 * R = 1.1759*Y + 1.2743*V
	 * G = 1.1759*Y - 0.3184*U - 0.6335*V
	 * B = 1.1759*Y + 1.674*U;
	 */




--
David Berry, david.berry@sun.com

"Humans don't have a zoom function. - Kryten, Red Dwarf"

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