Colour values for non-present RGB components are interpolated using routines that can vary from simple math to something more sophisticated. In any case, two thirds of colour information was not there in the beginning, pixel content is guessed. If you convert to B&W directly from RAW, you are not guessing, you are just reading the luminance information. And, do not forget that you can play with any of R, G or B values by multiplying with conversion factor to mimic either human eye photopic curve, film sensitivity, (panchromatic, old ortochromatic,..) or any filter you used long time ago with B&W film, light source temperature... For a uniform scene all B&W values should be the same, regardless of source pixel colour.
If none of contributors to this topic finds it wrong, I will add this RAW to B&W conversion to the list of feature requests. You can say that I am pushy
, but it looks so close to what could be a major enhancement when compared to standard image treatment in PowerShot cameras.
