Doug
12-08-2007, 11:34 PM
42 Capricorni is a Mag 5.16 G2V star. G2V stars are useful for setting the correct colour balance when converting 'one shot' colour raw files to RGB colour. These stars allow the setting of colour conversion values to give a good (correct) colour balance because they have the same spectral classification as does the Sum. In other-words, they provide us with a white balance the same as we would use in daylight terrestrial photography.
I had intended to post a Fits file of an (dark frame subtracted only) image of this G2V star, but then realised that the File is way too big to post here. The File would suffer if it were re-sized, cropped or otherwise reduced from its original size down to <150kb, so I have uploaded a Zip file to:
http://members.ozemail.com.au/~applejuice/G2V_42Capricorni.zip
The Fits file is a Raw file from a Canon 350D, and should be identical in respect to Bayer matrix with any other Canon 350D. It might/should be possible to scale the image to match other Canon and maybe Nikon DSLR files, (at least to use it for colour balance)
I have not applied one of my flat fields to it because it is your flat field which will effect the final colour balance.
So, I invite any interested persons to freely down load this file and use it to check/correct your colour settings in whatever program you are using.
If you are currently Image processing without the use of Flats, then the un-zipped file is ok as is, or if you use flats, apply your own flat to this and then set the colour balance.
Sadly this file will be of no use to DSI colour, Orion Star shoots, Web-cams etc.
When the correct colour parameters are set up for converting this image to colour, the R,G,B intensities of the pixels that belong to this star (center of Image) will each have the same value.
Try and keep the pixel intensities below 1.00 though, else colour balance will be uncertain.
any feedback/comment/ query welcome.
Enjoy and good luck,
Doug
I had intended to post a Fits file of an (dark frame subtracted only) image of this G2V star, but then realised that the File is way too big to post here. The File would suffer if it were re-sized, cropped or otherwise reduced from its original size down to <150kb, so I have uploaded a Zip file to:
http://members.ozemail.com.au/~applejuice/G2V_42Capricorni.zip
The Fits file is a Raw file from a Canon 350D, and should be identical in respect to Bayer matrix with any other Canon 350D. It might/should be possible to scale the image to match other Canon and maybe Nikon DSLR files, (at least to use it for colour balance)
I have not applied one of my flat fields to it because it is your flat field which will effect the final colour balance.
So, I invite any interested persons to freely down load this file and use it to check/correct your colour settings in whatever program you are using.
If you are currently Image processing without the use of Flats, then the un-zipped file is ok as is, or if you use flats, apply your own flat to this and then set the colour balance.
Sadly this file will be of no use to DSI colour, Orion Star shoots, Web-cams etc.
When the correct colour parameters are set up for converting this image to colour, the R,G,B intensities of the pixels that belong to this star (center of Image) will each have the same value.
Try and keep the pixel intensities below 1.00 though, else colour balance will be uncertain.
any feedback/comment/ query welcome.
Enjoy and good luck,
Doug