If you saw me process this image you would probably wonder what the hell is he doing. After stacking, manually, in photoshop I processed the aligned RGB channels and then stacked that manually on top of my processed Lum and aligned and faded colour. Then I stacked that flattened image on top of my Ha and aligned, then faded colour.
I have never attempted processing this image and will go away and do it again after some feedback. This is 3 hours Ha (20 min subs), 1 Hour Lum (12 x 5 Min subs), binned at 1x1 and 40 minutes of RGB (5 minute subs) binned at 2x2. A total of 6 hours. Any advice would be greatly appreciated as I think I have enough data so I would like to have a real crack at improving this one.
for starters it has great detail and potential... as you've no doubt heard a million times, blending Ha with RGB can be an utter nightmare with regards to colour balance. It seems like your Ha is washing out the red giving it a pinky appearance, and overpowering the rest of the colour..
A good idea is to process just the RGB, and have a look around on the net at other pics (Rob Gendler has done a real beauty) This will give you a good idea of the colour hues that you should be aiming for in your image, then adjust your colours to suit..
I believe you have great data, and definitely enough of it... it will take time but giving this a few repro's will be well worth the effort.
You've levelled your color channels with the Ha lum so you have none left in the pic. Try to mix 40% Ha in the red channel and 10% in the blue channel. Then copy your Ha as a top layer as 'luminosity' blend 20% opacity then copy the original color on top as 'soft light' blend and 50% opacity to start with. Tweak those two layers opacity until you get something you like. The neb on the right should hve deep red tones while the one on the left should be more orange in color. It's very obvious.
Firstly, you have some wonderful data there. The Ha loops are well defined and nice tight round stars. Well done. You're at first base.
As Alex and Marc have pointed out Ha blending is tricky business.
I myself am doing this exact same object and I have done this sort of thing a lot. But I got to the end and wasn't happy with it so I am also back to the drawing board.
I even started watching Adam Block's Ha blending tutorial (his tutorials are usually great but this one is very poorly done, very tedious and unclear).
There are basically 2 or 3 approaches to Ha. Marcus here is very good at the lum + Ha approach and Ha + red layer approach. This is Rob Gendler and Adam Block approach.
You basically make a blend of Ha and Lum and also Ha and red. It is not as simple as that though. It is beyond a short post here and I suggest if you want to use that technique have a look at Rob Gendlers site where he details it. Adam Block I believe has extended that technique further and is quite detailed and he has an educational DVD on his processing techniques which is very good.
Also I might add manually aligning all your subs sounds like very very hard work. Try a free trial of CCDstack for that sort of work. It does that hack work very well.
A simple yet powerful approach to Ha is:
1. Do your LRGB image as usual. Get it as nice as you would normally.
You could pump up the saturation a tad as it will eventually get washed a tad by the Ha as luminance.
2. Make a new layer call it Ha red.
3. Open your processed Ha image (get it to the point you would post it by itself). Copy it and paste it to the new layer. That is control A, control C click on the new layer to make it active then control V.
One point with Ha, I would tend to make the background of the Ha a little bit dark as you don't want your final image to have red background everywhere which it can easily so darken the background of Ha a tad using levels. Running a noise filter on Ha can also be good as you don't want little red dots in your final image either.
4. Set the new layer to lighten mode. Lighten mode means only those pixels below it that are lighter than the ones above it show through. You want this. This means the dimmer Ha stars which are awful won't wreck your lovely LRGB stars (or so the theory goes).
5. Duplicate this Ha red layer 2 times. Call one Ha blue and one Ha luminance.
6. Now make the Ha red laye active (click on the layer and it goes blue in the layers dialogue box).
7. Click on channels. Hold down the shift key and click on green and blue. Now control A and hit delete. You just deleted the green and red channel and left only red. Set opacity to suit the image. Perhaps 50%, perhaps 100%.
Now if you use curves and the curve is positive in shape then you boost the red and it goes above the LRGB image brightness and shows through. So now you have control over how much red will shine through - nice eh?
8. Do the same for the Ha blue layer except delete red and green.
Set opacity on the blue layer to only about 10% as you are only adding a small amount of blue to match the H beta content of the nebula and I am told its about 105 or thereabouts.
9. Set the Ha luminance layer to luminosity blend mode. Here adjust to suit and this you tend to only use a small amount of as it will create the salmon colours if done too hard. So perhaps only 20% opacity otherwise you're back to what you already posted - Ha luminace washing out your LRGB and creating a false salmon coloured look.
This is exactly what I do almost all the time with Ha and it usually works really well. This is essentially the Tony Hallas technique and I like it as it is simple and you have control over the reds, you don't have the horrible red stars (usually but a few seem to get through and you clean them up with the healing tool or clone tool).
It does assume a good Ha image to start with which is detailed and low in noise.
Thanyou all. It does seem like a new learning curve but I suppose that is all part of this passion we all seem to have. I'm glad to here and alwayss thought I had "good data" so now it is back to the tutorials and of I go.
Greg I really appreciate the effort you put into your responses which you have done for me in the past.
Tony Hallas and Adam Block DVDs are very good. There are others but these 2 are the most comprehensive. Tony is good because he gets to the point fast and does not clutter up the tutorial.
Adam is good too, although he occassionally waffles a bit but he is very indepth and covers the whole subject really well.
Interestingly they both bring unique data and you'll find techniques that are very handy.
If you had one of these and watched all of their tutorials you would have all the tools you need.
Mark, I have Adam Blocks and Tony Hallas's tutorials. I think it would be a great idea if we all got together for an image processing session. It'd be great to do it before Astrofest.
I'm definately up for that. What about sometime this coming weekend. Let me know as it would be good to catch up and have a laugh as well.
Mark
PS I just looked at the saturated M20 and that one should go straight to the pool room.
There'll be no time for laughing Mark. We'll be too busy honing our skills. I'm free this coming Saturday afternoon/evening. Have to work out a suitable time with the others though.
This is coming along quite nicely Mark. As has been said already blending RGB and NB data is quite tricky and no one rule works for every image. Marks method is quite simple and works on some while Gregs method is a little more cumbersome and also works on some images but it can be just getting something that suits you and then just a matter of experimenting time and time again.
Interesting stuff and the end result is often well worth the effort.
There'll be no time for laughing Mark. We'll be too busy honing our skills. I'm free this coming Saturday afternoon/evening. Have to work out a suitable time with the others though.
