This will be my first post of an image with all my new gear that isn't so new any more! It's taken me forever to get going with the PMX mount and a thousand camera driver issues (now resolved), not to mention the vagaries of processing, bad weather, etc. Anyway, enough preamble. Comments greatly appreciated as I'm really just in the beginning stages of learning how to do this. Compared to other Helix postings here I suspect I may have pushed the colour saturation a bit too far, but I kind of like the drama....
This is about 4 hours of capture total (6 min sub frames) in RGB using the Hutech IDAS LP filter from my back yard in Sydney. I collected luminance data, but using red as luminance looks better to me. I used CCDStack for the RGB, and CS5 for adding R(Lum), then LAB color to intensify, unsharp mask, and Noise Ninja to smooth. I am only partially successful in getting rid of blue bloat using the minimum filter on the blue channel. There are some dark star boarders on some stars embedded in the nebula which I would like to eliminate. I'm not sure how to do that. Any and all suggestions will be appreciated! Thanks for looking!
Peter
Edit: I just looked at this image on a friend's computer. I am pretty surprised that it looks very over saturated and dim. I think I cannot edit any longer on my laptop screen....it's way too bright.
I've made some efforts to reprocess on a different computer/screen but running into all sorts of issues. Eventually I'll post something new, but probably not for some time!
That looks great. I like the colours.
How does this version look on your monitor? There is quite a bit of detail but the noise or compression artifacts show up a bit.
Not sure what you meant by using Luminance in Red, wouldn't that skew the data, unless that's a common method.
That looks great. I like the colours.
How does this version look on your monitor? There is quite a bit of detail but the noise or compression artifacts show up a bit.
Not sure what you meant by using Luminance in Red, wouldn't that skew the data, unless that's a common method.
Hello and thanks for making this effort with my image. On my laptop it looks a bit too bright, but on a friends Mac it looks better than mine, but the background look poor. This is the same problem I'm having when trying to proces my data from scratch on another computer. I'm not too sure why the sky values are proving quite so difficult. On my original effor the sky looked ok without black clipping, but not when I try to get a brighter nebula AND a dark sky.
My understanding of luminance data is that you can use any data you want for that channel....so, if red, (or Ha or red blended with Ha) shows more detail than the clear filter you can use it in place of the clear filter. So, in effect the RGB channels mostly provide colour into whateveer channel is placed in the luminance channel. My red channel looked way sharper than clear so I decided to go with red.....so: RRGB.
Peter
Hi,
Does your Laptop use the proper driver for the display? if so does it have any colour correction features? you could try upgrading with the manufacturer driver and they usually have various settings, I've opened this image on around 3 computers and an iPAD, and they all look the same to me which indicates perhaps your laptop calibration is way off.
As for the background noise, yep I saw that as well. Did you dither between subs? that should reduce noise.
Hello Peter, that's a very nice first image!
In terms of the background mottling, this could be due to over smoothing and/or the fact that using the red channel only for luminance will have more background noise than an equivalent exposure with a luminance filter. Perhaps you could try blending some luminance data in the luminance channel and/or maybe target the dim areas in Photoshop to blend in the luminance data.
I was also wondering when using LAB for your colour space do you convert back to sRGB before saving as a jpeg for the web? I'm no expert here, but I believe that many web browsers don't colour manage so the image may look different to what you see in Photoshop if you have saved in a different colour space.
That's a great effort Peter, and from Sydney..? ...
Using Red as the Luminance is perfectly valid and useful with some objects particularly emission nebulae and would lessen the affects of light pollution too, bit like a broadband Ha filter really.
1. Yes, all from North Curl Curl, NSW where the sky is hardly ever very dark let alone clear. I think the Hutech IDAS filter is helping quite a lot.
2. My laptop, an ASUS G53SW has a very bright screen. It's pretty useful though with illuminated keys when outdoors. I may try processing with the screen turned down more. I've tried to calibrate the screen but my efforts have not proven very successful (yet).
3. Yes, in retrospect the colour data was all 2x2 binned, so trying to get some sky in from the lum (1x1) would probably help quite a lot. I may try that but I'm kind of tired of working on the Helix and want to mve on to another target for now.
4. Re LAB colour.....This is a method I learned from Adam Block's Photoshop tutorial. Basically convert RGB to LAB, then adjust the A and B channels using contrast adjustments. This seems to work better than just increasing saturation. After processing convert back to RGB.
5. At the moment I don't have an imaging program that will allow me to dither. It's promised in the next update of the camera driver for The Sky X. I currently guide from TSX using the ST-1, focus using CCDSoft/FocusMax, but image using SIPS which came with the Moravian camera. At this point I'm reluctant to pay a lot for MaxIm just to dither much as I'd like to dither.
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