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M101 - Pinwheel Galaxy - LRGBHa - 30/4/13

Gina

By Gina
in Imaging - Deep Sky

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Uranium235

Uranium235

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Have to agree with the use of high pass filters or other contrast enhancement routines as its noise-free enough to take a little more processing. Maybe another couple of hours L? That would give you even more headroom when processing :)

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Gina

Gina

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That's a lovely image Gina, one that so far I have avoided as it seems to be rather difficult.

Dave

Thank you :) Give it a try Dave - after all, nothing ventured nothing gained :)
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Gina

Gina

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Thats a great image Gina! Beautiful.

It can easily stand a bit of sharpening? A couple of iterations of High Pass makes the dust lanes really "pop"

Thank you :) Yes, the processing was just a quick go and you've proved there's more to be got out of the data with more processing - thank you for that :)

Talking of processing I realise that I didnt give all the details. After aligning with RegiStar I stretched the groups in PS and then added Ha to the red with 66% opacity and to the blue with 25% opacity, further adjusting curves etc. Then took the Red+Ha and duplicated it as the base for the colour. Changed from greyscale to RGB and replaced the green channel with the Green stack and the Blue with the Blue+Ha. That was followed by adding the Luminance as Luminosity layer and further processing and flattening. I didn't do any sharpening or noise reduction or other filtering.

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Gina

Gina

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Have to agree with the use of high pass filters or other contrast enhancement routines as its noise-free enough to take a little more processing. Maybe another couple of hours L? That would give you even more headroom when processing :)

Thank you for the advice :) If it's clear tonight I might take some more L subs. I think there's enough of everything else. I had a change last night and did M51.
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RobH

RobH

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Coming along nicely there Gina.

It's still a bit noisy as you've not really got that much exposure time on it yet, and the use of any sharpening will increase the noise levels at this stage.

I'm a little extreme perhaps, but I'd say it could do with a doubling up of the data all round. This will give you lots more opportunity to sharpen/stretch etc.

It's actually quite a tricky object to process!!

Cheers

Rob

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Gina

Gina

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Thanks Rob :) I'me taking more data on this at this moment. I have a sequence set up for 2x10m L and 3m each for RGB binned 2x2. That should grab quite a lot more L and a bit more colour.

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Gina

Gina

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Nice amount of LRGB data captured overnight in spite of a confused start.. 16x10m Lum with 3x3m + 5x4m each RGB binned 2x2. These subs were added to the previous LRGB subs and stacked in DSS. The Ha subs from the other night were stacked separately. The saved stacks were aligned with Registar and the 5 resulting images opened in PS and the histogram stretched with Curves and Levels - more or less matching.

Next 50% Ha was added as a layer to the Red and 15% Ha added to the Blue and both flattened. A small amount of Ha (about 20%) was added as a layer to the Lum data and flattened. This was then sharpened slightly. The resultant Red was duplicated to form the base for the colour image and changed from greyscale to RGB colour. Then the Green channel was replaced with the stretched Green stack and the Blue replaced with the Ha/Blue combined image. With all colour channels selected, the view was changed to Layers and the Lum combined image added as a layer and set to Lumiunosity. Finally, further tweeking was performed in PS to pretty up the image.

post-13131-0-51418000-1367588700_thumb.p

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RobH

RobH

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Hi Gina.

I like the way you've added the 30% Ha to the blue to take account of the h-beta component. Although that's not uncommon when imaging nebulae, I've never heard of it being done with galaxies but of course makes sense and I'll be doing thast myself from now on :icon_salut:

I'm surprised that it's still quite noisy after over 4 hours of luminance though.....what processing have you done on the luminance channel?

Cheers

Rob

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Gina

Gina

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Hi Gina.

I like the way you've added the 30% Ha to the blue to take account of the h-beta component. Although that's not uncommon when imaging nebulae, I've never heard of it being done with galaxies but of course makes sense and I'll be doing thast myself from now on :icon_salut:

I'm surprised that it's still quite noisy after over 4 hours of luminance though.....what processing have you done on the luminance channel?

Cheers

Rob

Thanks Rob :) Histogram stretching and smart sharpening also a small amount of Ha so that the Ha shows when Red and Blue channels are multiplied by the Luminance.
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RobH

RobH

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Thanks Rob :) Histogram stretching and smart sharpening also a small amount of Ha so that the Ha shows when Red and Blue channels are multiplied by the Luminance.

Apply sharpening selectively Gina. Sharpening applied to the background/faint areas will dramatically increase the noise.

There are several ways to do this, the simplest being to add another layer, sharpen that, then add a layer mask set to 'hide all' (Layer/layer mask/hide all). Then you erase the layer mask over the areas where you want the sharpening to show through using the eraser tool. Set the tool to very low opacity and flow (no more than 10-15%) and carefully reveal the sharpened areas.

Cheers

Rob

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Gina

Gina

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Apply sharpening selectively Gina. Sharpening applied to the background/faint areas will dramatically increase the noise.

There are several ways to do this, the simplest being to add another layer, sharpen that, then add a layer mask set to 'hide all' (Layer/layer mask/hide all). Then you erase the layer mask over the areas where you want the sharpening to show through using the eraser tool. Set the tool to very low opacity and flow (no more than 10-15%) and carefully reveal the sharpened areas.

Cheers

Rob

I'll give that a go - thanks Rob :)
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Gina

Gina

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I've done a complete reprocess of all the data collected on 30th Apr and 2nd May with DSS set to Kappa-Sigma clipping. Some differences in the processing. Used Smart Sharpen on the Lum and Ha and Gaussian Blur on the RGB then added the Ha using Lighten mode for the Ha layer on Red 100% Blue 25% and Lum 50%. Adjusted levels and curves etc. and applied Sara's Lab colour mode to increase the colour. Here's the result :-

post-13131-0-95046800-1367788574_thumb.p

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Gina

Gina

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Well I started off impressed but I think you've really nailed it with this latest re-process Gina! Such a tricky galaxy to image as well, well done :)

Thank you Chris :) I agree that this reprocess is a lot better :)
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