qccimgimagecolorsnr.3

spiht for linux this is used to decod and encode vedio i wich all enjoy

.TH QCCIMGIMAGECOLORSNR 3 "QCCPACK" ""
.SH NAME
QccIMGImageColorSNR
\- 
copy image
.SH SYNOPSIS
.B #include "libQccPack.h"
.sp
.BI "double QccIMGImageColorSNR(const QccIMGImage *" image1 ", const QccIMGImage *" image2 );
.SH DESCRIPTION
.BR QccIMGImageColorSNR()
calculates a color distortion between two images.
This color distortion is a signal-to-noise ratio (SNR)
based on the 1964 CIE formula for
the distance between two colors as calculated in the
CIE Modified UCS color space.
.BR QccIMGImageModifiedUCSColorMetric (3)
is used to calculate these UCS color-space distances.
.LP
Both
.IR image1
and
.IR image2
must have the same size.
Furthermore, all three YUV image components within each image
must be the same size as well.
.SH "METHOD"
If the pixels of
.IR image1
are 
.RI ( U1 ", " V1 ", " W1 )
in Modified UCS color space,
and pixels of
.IR image2
are
.RI ( U2 ", " V2 ", " W2 "),"
the color SNR between the two images is 
.I SNR
= 10 * log 
.RI ( D1 
/ 
.IR D2 ).
.I D2
is the average squared distance (1964 CIE formula) between the two images,
.IR D2 " = mean((" U1 " - " U2 ")^2 + (" V1 " - " V2 ")^2 +
.RI ( W1 " - " W2 ")^2)."
.I D1
is the average squared distance between the pixels of
.IR image1
and the 
mean color, 
.RI ( u1 ", " v1 ", " w1 ") ="
.RI (mean( u1 "), mean(" v1 "), mean(" w1 )),
of
.IR image1 ;
that is,
.IR D1 " = mean((" U1 " - " u1 ")^2 + (" V1 " - " v1 ")^2 +
.RI ( W1 " - " w1 ")^2)."
.SH "RETURN VALUE"
This routine returns the value of the calculated SNR, or 0.0 in
case of an error.
.SH "SEE ALSO"
.BR QccIMGImageModifiedUCSColorMetric (3),
.BR QccIMGImage (3),
.BR QccIMGImageComponent (3),
.BR imgdist (1),
.BR QccPackIMG (3),
.BR QccPack (3)

.SH AUTHOR
Copyright (C) 1997-2009  James E. Fowler
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