Monday, August 09, 2010
RGB vs. RRGB in planet photography
If you are a planet photographer and you make video sequenses with a color webcam, I have a good tip for you. After adding the avi video stream with GIOTTO or Registax, separate the R/G/B channels with MaximDL or GIOTTO. Copy the R channel to a new file to use it as luminance. Finally load all four files in CCDSoft to make a RRGB composite. You can compare the results on the photo above.
The RRGB processing brings out invisible details of a RGB photo. My RRGB composite above is sharper than the RGB although I think the RGB has better colors than the RRGB. One problem I can mention, is that the red channel as luminance can not match the green or blue details of the planet. Normally, a "real" luminance channel should match all the colors of a RGB photo. That's not the case in RRGB. But as you know, the red channel is immune against atmospharic turbulences, this is the reason why in MY case the red channel shows more details than the green channel. The bayer mask of an OSC cam has two green pixels but only one red pixel. Hence the green channel could better serve as a luminance channel under perfect seeing conditions (in the space ;-). I think so. If a reader has a suggestion please comments this topic. Thanks.