IC59 & 63 in Cassiopeia

[martin_h]

This is my first attempt at Ha imaging with the QHY8...After much searching and reading on the subject I've come up with this effort.

There is about 5 hours of RGB data but only about 2 hours of Ha, so I stripped the red channel from the RGB and combined it with the Ha to make HaR the recombined it with the original RGB. So we have HaR-RGB.

Any/all comments tips etc.......

[MartinB]

You have a lot of cyan in there. I suspect the problem arose when you combined the Ha with the red. This image looks like an HaGB shot. Worth trying a different method. Process your RGB and Ha seperately. Don't complete the full Ha stretch. When processing the RGB leave the histogram some way over to the right i.e. don't fully adjust the black point. Make a duplicate of the RGB and use soft light as the blend mode. Adust the opacity to taste (remembering you can play around with this further when you add the Ha). The soft light will enhance saturation and allow the star colour to show through the Ha layer.

Add the Ha layer and use lighten as the blend mode. You will now need to finish the histogram stretch to get the blend to suit.

You can also add an ha luminence by doing a straight luminence process (don't over do the stretching though) and add to your colour image using luminosity as the blend mode. This will have the effect of desaturating you image a little and turning the red to a salmon colour. To reduce this you will need to turn down the opacity until you are happy with the result.

There is a lot of playing around to do between the levels but this method gives you a lot of control.

[Whippy]

That's a good effort there, this is a real faint one and on top of Martin's advice I think some more time spent on it would reap rewards too.

Tony..

[cardconvict]

I don't know if you have seen this but i will post it anyway maybe for others, but this is how how blend the HA

thanks doug here is the link http://starizona.com/acb/ccd/software/ps_hargb.aspx

[namreg]

Was there supposed to be an attachment or link in that message Ian?

[cardconvict]

updated

[namreg]

That's a useful site. Not that I'm into Ha and stuff, but one day....

[martin_h]

I don't know if you have seen this but i will post it anyway maybe for others, but this is how how blend the HA

thanks doug here is the link Starizona's Guide to CCD Imaging

Thats what I used - but made a dogs dinner of it LOL - will have another go at it sometime.

[cardconvict]

did you try method 2 that one always works for me

[martin_h]

Method 1 - but I pasted the HaR into the RGB instead of the red channel only - oops.

Will give both methods another go later.

[MartinB]

Martin, there are lots of "methods" people use and the Starizona one will work fine in most situations. The problem is that everyone's data is different and different targets behave differently. I think you probably used the starizona method correctly but the end result was not enough of the bright, non Ha red being transmitted through to your HaR channel.

Inevitably, which ever method you use, you need to be able to make adjustments to different aspects of the image on the fly to experiment with the effects of changes. This is why I prefer to create a stand alone colour Ha (which has a bit of blue added to it to give a truer representation of Ha colour) and use that as a seperate layer. I like to end up with 2 colour layers, one a duplicate of the other, a colour Ha layer and a luminence layer (which may be 100% Ha or may have bits of non Ha data added). A seperate star layer can also be used from time to time.

This multilayer approach gives enormous control over blending the Ha colour with RGB colour.

If you have a look at Cardconvict's flaming star you can see how well the Starizona method works but I imagine that he has used some judgement at some point in adjusting blending opacities and such like. I used to feel guilty about having to resort to trial and error with Ha composite images but I now think it is an essential part of the process!

[cardconvict]

Hi martin so a quick summary as i use one shot colour if this sounds right, with the HA data i get after i stack, i get the HA from the red channel and discard the rest, process that and then combine that with the blue channel to make HAB, then put that back in as a colour layer and the rest i do anyway for the luminance, or do i take the blue channel out of the HA data and discard the rest and combine that with the blue channel in the RGB, i think i'am going to have a play with this but does that sound right thanks Ian

[MartinB]

Ian, Use the Ha red channel for both red and blue. Create the red and process but don't fully stretch, because you will want some head room when making final adjustment, duplicate and convert the duplicate to greyscale. Then convert back to RGB. In channels delete the red and green leaving a blue image. Then paste this onto the red image and select between 10-20% as opacity. That will give you a properly hued Ha (although compared with plain red the difference is subtle)

[martin_h]

Re-Edit..It looks a bit better I think

[MartinB]

Hi Martin,

Thanks for sending me the RGB and Ha tiffs. I've had a go at processing. I've kept mine a bit more subdued than yours. I found I could push things to pull out a bit more nebulosity but the rest of the image suffered badly.

I processed the RGB, a red Ha and a mono Ha. I added a duplicate RGB layer and used soft light as the blend mode with an opacity of around 60%. Then added the red Ha using lighten and tweaked the levels and curves to bring it into play. Then added the Ha mono using luminosity and an opacity of 45% - this just helped pull out the dimmer parts of the nebulosity a little.

I applied some noise reduction and reduced the stars a little. I used Noel's star spikes pro software to add some cosmetic camouflage to the bloated stars.

The Ha data was very weak. It would probably have been better to swap the total exposure time between RGB and Ha. The RGB was also slightly out of focus. This effected the stars but will also have hit your sensitivity.

It's a tough target.

[martin_h]

Thanks for having a play with that. The Ha was just an after thought realy and the weather finished it off for me. My re-process (above) was without the Ha.