Background extraction -color calibration - star fields?

[astropixel]

A few questions concerning BackgroundNeutralisation and ColorCalibration.

Reading the documentation and applying the principles to images dominated by star fields, is the best approach to use the entire image as a background reference and select an area of bright stars / nebula as white reference - would this include nebula color as well?

Should structure detection be selected (default) in order that star colours are retained as much as possible?

In this case, is ABE / DBE absolutely necessary, given the absence of a background - e.g., would BN be adequate in these situations? I note Harry's comment about the small amount of background samples required for successful extraction. How should background be defined in this case, where star fields are interspersed with dust lanes.

Cheers

R.

[astropixel]

OK. Perhaps answering my own question, I set the sample size in ABE at 1 pixel and left the other defaults as they are. Big difference indeed, and colour more manageable.

The issue that I cannot resolve myself, is the predominance of blue in images taken with no light pollution filter, and strong blue tones in areas of dust. Is this just sky glow that is being registered by the sensor?

[pfile]

blue tones even after DBE or ABE?

the only blue i ever seem to get is fringing around stars in dense star fields, like in the plane of the milky way. this seems to be due to the inability of my lens to precisely focus R,G,B in exactly the same plane. depending on what side of focus i end up on i might have a red cast to the star field as the red channel stars are bloated, or a blue cast when the blue channel is bloated. usually i'll have to do some star reduction on just the problem channel to get the stars looking a little more white (or, rather, non-red/non-blue)

[astropixel]

No problem with stars, except coma in the margins. It's the dark areas where blue is dominant. This is the latest rendition.

 http://synergous.com/photos/picture.php?/173/category/4

[astropixel]

For completeness, it appears that white balance is the issue and Zbynek has kindly provided assistance on the use of his module, AssistedColorCalibration. Significant difference.