Helix Nebula - Question

[wouterw]

Hello,

Can anybody explain the black specks and background graininess (i did apply dark frames) ? Can this be removed using image processing software ? This is an image of the Helix Nebula, taken with a Meade DSI III camera, 61 light frames of 5 minutes exposures combined.

Thank you.

 

[Knight of Clear Skies]

I suspect the pattern is composed of camera artifacts stacked together. Have you tried dithering and a Kappa-Sigma clip when stacking? That's very effective at removing background noise patterns.

[wouterw]

Hello,

No, i did and average when stacking. Dithering should be done while imaging ? Unfortunately didn't apply dithering while i was taken the images.

Thank you.

 

 

[ollypenrice]

Sigma may still work very well without dither, especially with 61 subs.

A Photoshop 'fix' is to zoom in to pixel scale and use the colour select tool (experimenting wth the fuzzines slider, but try 8 for starters) and when you have the dark rogue pixels selected, apply the Median filter in Filters-Noise. This will give the rogues the average value of their neighbours.

Olly

[wouterw]

I tried some processing in Photoshop, below is the result, using the noise filters.

Thank you.