Banding

[RichInLesta]

I've been scratching my head trying to figure out if/where I went wrong with processing my Orion images.  It's only my second astroimage, so I'll assume it's something in my workflow that I need to correct.

The problem I'm having is the appearance of banding in my image (I'll be more explicit in a moment).  What I see throughout processing, from initial images through the final product are horizontal bands.  They're quite faint in the final, but once your eye picks them up they're rather noticeable.  I think the best way to explain is to demonstrate what I'm seeing step-by-step in the process.

But first, the details:
Orion Nebula
Celestron 8" SCT with AVX mount
0.63 focal reducer
Canon 70D
50 15-second lights at 100 ISO
Super Bias (I also tried with a Master Bias)
Master Dark
Flat Frames
(If details of how I created the masters are pertinent, i'll provide that info, but for now I'll leave that out for brevity)

Here is one of the lights (when you stretch it, you'll see that it's fairly clean however there is some faint horizontal lines which I believe are normal but which seem to carry through the process)
https://www.dropbox.com/s/z6npnxqhqpxzacv/1%20-%20ORION%20NEBULA_LIGHT_15s_100iso_%2B41f_20161230-21h52m23s628ms.CR2?dl=0

This is that same frame after Calibrating with a Master Bias, Dark and Flat (will look somewhat similar to the original frame, but with more noticeable horiz lines)
https://www.dropbox.com/s/ut49k2avgj4bs8p/2%20-%20Calibrated_ORION%20NEBULA_LIGHT_15s_100iso_%2B41f_20161230-21h52m23s628ms_c.fit?dl=0

Same frame after Cosmetic Correction (no change, but I didn't want to skip a step)
https://www.dropbox.com/s/myekmqri0s9s3ot/3%20-%20Corrected_ORION%20NEBULA_LIGHT_15s_100iso_%2B41f_20161230-21h52m23s628ms_c_cc.fit?dl=0

Same frame after debayering (bands seem to be more noticeable)
https://www.dropbox.com/s/j8ismsjtzpl87tc/4%20-%20debayer_ORION%20NEBULA_LIGHT_15s_100iso_%2B41f_20161230-21h52m23s628ms_c_cc.fit?dl=0

Same image after Star Align (similar to the image after debayering)
https://www.dropbox.com/s/e8e9px5grfmxy59/5%20-%20Aligned_ORION%20NEBULA_LIGHT_15s_100iso_%2B41f_20161230-21h52m23s628ms_c_cc_a_r.fit?dl=0

After image integration (integration of the 33 best frames)
https://www.dropbox.com/s/lnxtzgftx09k4xe/6%20-%20After%20Image%20Integration.fit?dl=0

After drizzle integration (cleaner, but bands still visible)
https://www.dropbox.com/s/rcfif0m49psji63/7%20-%20drizzle_integration.fit?dl=0

Final Image (I tested MANY configurations such as omitting the Darks, Bias, etc. to see what difference it would make and this was the best result - which was calibrated with ALL masters)
https://www.dropbox.com/s/df1ltsp5gz29aob/Processed%20010817.tif?dl=0

As you can see in the final image, there are faint blue bands that stand out once detected.

I ran out of room in my Dropbox, so if you think you want to see any of the Masters I can make room and make them available.

I'd like to understand the source of the bands; would I have introduced them in lights collection? calibration with the Flat and/or Bias and/or Dark?  Could my processing workflow be missing a step to remove them?  (FYI, I followed pretty much the Andromeda workflow posted here: http://www.lightvortexastronomy.com/tutorial-example-m31-andromeda-galaxy---dslr.html)

Thanks, in advance, for any direction you could provide.

[msmythers]

This is called Canon Banding noise. I can't tell you anything about it as I don't have a Canon but there is a script in the Utilities section for this. Again I just don't know anything else.

I ran the script just with the defaults on your single sub. Attached is the result.


Mike

[RichInLesta]

OMG, that's an amazing difference.  You're my new best friend! 

I'm generally pleased with the outcome as I currently have, but if the "new" results are as improved as this one sample, i'll be ecstatic.

Thanks again.