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  • egg126June 24, 2009 8:26 PM PDT   
    The Equation of YUV to RGB
    Hi, all

    What's the Equation of IPP to implement the YUV to RGB

    ippiYUV420ToRGB_8u_P3C3(const Ipp8u* const pSrc[3], Ipp8u* pDst, IppiSize imgSize);

    There are difference of my result with IPP. So I want to know what's the equation of IPP to implementation...

    Thanks for your reply.

    pvonkaenelJune 25, 2009 9:50 AM PDT
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    		 #1
    Re: The Equation of YUV to RGB
    Quoting - egg126
    Hi, all

    What's the Equation of IPP to implement the YUV to RGB

    ippiYUV420ToRGB_8u_P3C3(const Ipp8u* const pSrc[3], Ipp8u* pDst, IppiSize imgSize);

    There are difference of my result with IPP. So I want to know what's the equation of IPP to implementation...

    Thanks for your reply.

    I don't know how the internals are implemented, but if you're getting different results then you might not be using the correct conversion routine.  Are you sure you have a YUV source and not a YCbCr source?  If you're working with video then it's probably YCbCr.

    Peter


    egg126June 25, 2009 7:37 PM PDT
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    		 #2 Reply To #1
    Re: The Equation of YUV to RGB
    Quoting - pvonkaenel

    I don't know how the internals are implemented, but if you're getting different results then you might not be using the correct conversion routine.  Are you sure you have a YUV source and not a YCbCr source?  If you're working with video then it's probably YCbCr.

    Peter

    Yes, that's YUV Source, and the I find in ippiman, the Equation is:
    R' = Y' + 1.140*V'
    G' = Y' - 0.394*U' - 0.581*V'
    B' = Y' + 2.032*U'

    But my result is different, so I want to know How IPP implement this Equation in Integer Operation.

    Also, I find the YCbCr to RGB is available. That's ippiYCbCrToRGB_8u_C3R
    And the Equation is:

    R' = 1.164*(Y' - 16) + 1.596*(Cr' - 128)
    G' = 1.164*(Y' - 16) - 0.813*(Cr' - 128) - 0.392*(Cb' - 128)
    B' = 1.164*(Y' - 16) + 2.017*(Cb' - 128)

    And, at present, I want to know How to implement them(YUV2RGB, YCbCr2RGB) in Integer Operation.

    Thanks very much...

    egg126June 28, 2009 9:35 PM PDT
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    		 #3
    Re: The Equation of YUV to RGB
    Is there anybody know how to optimization this equation in Integer Operation.

    R' = Y' + 1.140*V'
    G' = Y' - 0.394*U' - 0.581*V'
    B' = Y' + 2.032*U'

    and

    R' = 1.164*(Y' - 16) + 1.596*(Cr' - 128)
    G' = 1.164*(Y' - 16) - 0.813*(Cr' - 128) - 0.392*(Cb' - 128)
    B' = 1.164*(Y' - 16) + 2.017*(Cb' - 128)


    And I use floating point operation, but the result is different with IPP, the gap is just 1, therefore, I think this is round error, however, I don't know, How IPP round this equation?

    Thanks very much.


    Vladimir Dudnik (Intel)July 6, 2009 7:39 AM PDT
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    		 #4 Reply To #3
    Re: The Equation of YUV to RGB
    IPP use SSE optimized fixed point calculations in YUVToRGB conversion for 8-bit input and output data. This is much faster comparing with SSE floating point calculations (which will require integer to float and back conversion) but introduce rounding error.

    Regards,
      Vladimir



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