I have finally had the time to capture some good data and have a play with my narrow band filters.
Never done a combination before so be gentle. At the moment this is just a proof of concept so only deconvolution to the LUM and some noise reduction to the RGB then curves and combine.
I am colour blind Red/Green so i have no idea how close i am to a correct balance so advice would be helpful in this field particular i asked my wife but she thinks if great as is (also she has no idea what it is).
Very nice for your first attempt! The star colours look very good for a narrowband, they have RGB like qualities. The nebula colour isn't quite right but in saying that, you cannot have both at the same time without masking one and messing with the other.
Welcome to both the Narrowband club and the hugely popular Colourblind Astrophotographer's Brigade.
A quick statistical analysis shows that you could clip your dark point on all three channels by about 9000 counts without losing any data, thus making the image much more contrasty, and that the colour balance is, if you belong to the widely accepted "colour agnostic" school where the task is to show relative colours rather than absolute colours, also statistically faultless.
I'm colourblind to the extent of having no red receptors at all (1 in 1000 males, as opposed to the usual milder anomalous trichromat form (1 in 12), so I've thought about this a lot and written my own image processing software (GoodLook 64) to make it easy and painless. Sod's Law states that I'm just about to release the next version in about a week, so if you can hold off till then, I'll post a link. It's fully functional (subpixel level registration, powerful rejection of satellite trails, hot pixels, bad columns, etc, mosaics, deconvolution, wavelet noise reduction and sharpening, arcsinh stretch, zero, contrast, colour balance, masks, starless processing, the lot, and supports FITS and TIFF). Also free to a good home.
Some general techniques on image processing for the Brigade:
(1) Have a button where I can instantly switch the red and green channels (or red and blue channels). Flicking back and forward gives me some idea of what others can see in the red channel, using my green (or blue receptors).
(2) Close, microscopic analysis of the foothill of the histogram in each channel to set the zero point without any colour cast or data loss.
(3) Tools to make the image as a whole, or a region of interest, colour neutral.
The really tricky bit with narrowband is when you start doing Ha/OIII/SII images, and trying to balance them. You get spectacular magenta rings round stars, which can be very distracting to people with colour vision. I've developed good tools for handling those. Basically, divide image into stars and starless, process the starless image, then put the H-alpha only stars back into the image as white.
Nice work Grady and congrats on your first narrowband image! I'm relatively new to the narrowband game as well, and getting the colour looking nice is a challenging task for me, and I'm not even colour blind.
The repro is giving it a bit more pop which is nice, but it has created a reddish cast to the background, so I'd probably pull down the red in the shadows a touch.
I like that a lot Grady. It's very good for a first attempt at NB and particularly so given that the veil isn't very high in the sky even from Brisbane.
I have finally had the time to capture some good data and have a play with my narrow band filters.
Never done a combination before so be gentle. At the moment this is just a proof of concept so only deconvolution to the LUM and some noise reduction to the RGB then curves and combine.
I am colour blind Red/Green so i have no idea how close i am to a correct balance so advice would be helpful in this field particular i asked my wife but she thinks if great as is (also she has no idea what it is).
I'm pretty happy with the ASI 1600 so far :-) If my calculations are correct, I'm sky limited with L subs at a (approx) bortle 3 site, with 60 second exposures. Gotta love that low read noise...
Yes a great first go! Love the RGB look stars, and the reprocess was well worth it. As ever, a little more data might help the neb stand out more.
Haha I'm another NB virgin, constant purchases causing mammoth overcast skies down here. I have a FW full of top notch Astrodons gathering 'dust', getting rather sick of waiting. Oh well, it might give me time to perfect cabling.
