Thanks, lexa.

I do this when is it a mixed pixel.

// It's a mix pixel from various images
gray16_pixel1 = *vct_gray16ViewSrc_iterator[i-1];
gray16_pixel2 = *vct_gray16ViewSrc_iterator[i];
drFC1 = vectorRFC[i-1];
drFC2 = vectorRFC[i];
m2 = static_cast<double>(*dbl_vct_it) - static_cast<double>( i );
m1 = static_cast<double>(1) - m2;
mul1 = drFC1 * m1;
mul2 = drFC2 * m2;
 
gray16_pixel1 = gray16_pixel_t(round( static_cast<double>(gray16_pixel1) * mul1 +
                                                                static_cast<double>(gray16_pixel2)   * mul2 ) );

If you look m1 and m2 they are weight compensed to 1 in a cell. see m1= 1 - m2

Sorry, when you talk about 'pixel' ... it is a cell, like 'R' or is it about four cell like the group(R,G1,B,G2) ?

NOTE: I use gray16_pixel_t because are simple values, from 0 to 65535 and dont have components (like red,green,blue)