After having the opportunity to work with images from a really dark site, a terrific Takahashi telescope, and very narrow band S, H, and O filters, it is a bit of a letdown to come back to my own OSC camera...

Narrowband images show superb detail contrast, I think mainly, by limiting the growth of star images. The nebular features are rich at very precise wavelengths, while stars are broad band black bodies. Therefore, if you can limit the bandwidth to a narrow region around the nebular spectral lines, they come through loud and clear, and relatively little starlight manages to hog the image.

So what to do with a very broadband OSC camera? The panels show two different LRGB constructions from the same image set taken with my ATIK-490 color camera. The left shows the usual image stretch, where the elephant trunk is almost lost in the surrounding star field. On the right, I modified the Luminance layer by dimming the stars using wavelet transforms, without affecting the nebula details. There are still lots of field stars, but now the elephant trunk manages to stand out a bit better.

So all is not lost with a garden variety camera like mine. It will never be as sharp and elegant as a narrowband image, but we can squeeze more out of an OSC that you might imagine.

Completely removing the stars is not really an option because it looks too unnatural.

The Luminance channel is derived as the statistical weighted average of the R, G, and B components of the image. You can stretch the L band and generally change the display of intensity, while the original RGB image provides the chrominance and hue.

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I had another look at the data... this data set is very photon starved in the nebula. Even the SHO data set with 24 hours of integration looks rather dark. So part of the problem also seems to be "not enough photons". I'll have to look again in the coming months.