MrsGnomus

46 minutes ago, emyliano2000 said:

Oh, I would love to see that!

So would I!

A couple of months ago I started drawing up a list of potential galaxy targets for the TEC/QSI690 rig that Steve and Barry have at E-EyE - when I checked the list this morning NGC 3718 (& NGC 3729) was the first thing I had put on the list. Olly has the same FOV with the Atik 460 side of the twin TEC rig.......

8 hours ago, ollypenrice said:

Martin Pugh and Paddy Gilliland both found strong blues in the spiral arms. I'd like to go back and try to find this because, in the data I have, I didn't find it.

 

Another project for the twin TEC rig perhaps?

1 hour ago, gorann said:

Did you use Gaussian blurr on it?

I have no idea if I used Gaussian blur or not! What I did use is Noel’s Deep Space Noise Reduction. It’s entirely possible that Gaussian blur is one of the steps in that recipe.

35 minutes ago, tooth_dr said:

What talent in this thread!  Just shows you no matter how good your scope/camera/skies are, if you cant process the data you'll end up with a lemon.

In the Gnomus household we think that the majority of the skill is in the processing and not in the mechanics of setting up the equipment.  Even I can tighten up bolts and plug in cables! We have had a few trips to Olly’s and watching him process his data (not all of which could be described as pristine ?) has helped us both enormously. I would go as far as saying that it was only after the first of those trips that our processing started to go in the right direction. I still have the copious notes that I made while Steve processed the Seagull image that I use as my avatar under Olly’s supervision. Each time we go we learn something new - for example on our last visit it was which brand of self destructing filter wheels to avoid!

25 minutes ago, gorann said:

So, here is what I came up with today. I used artificial Lum from the RGB data as suggested by Wim (to avoid the dust bunnies). Now when I see Mrs Gnomus new magnificent version I may have another go a sharpening (deconvolution) so it is possible that I come back with a new version. Maybe I should look into what the Lum data looks like and possibly use it selectively on the galaxy so I no not have to deal with the bunnies. Al done in PS CS5 (using the files Nigel had stacked).

Thanks Nigel for this entertainment! If you do not mind I may put it on my Astrobin with full credits of course.

 

Thanks Gorann.  I think it is worth using the Lum for the galaxy itself.  Even though there was >6 hours of RGB, the false Lum taken from this wouldn’t be equivalent to 6 hours Lum, at least I don’t think it would.  However, the Lum artefacts were a nuisance.  I took the full LRGB image and the RGB only image into Photoshop.  I adjusted the RGB so that the background sky matched that of the LRGB image as closely as possible. I placed the RGB on top of the LRGB as a layer. I then changed the blending mode to Luminosity.  I think this is the same as extracting the Lum and using that.  I then applied a mask to the RGB layer and used the paintbrush tool on the mask to allow the RGB background to come through, whilst keeping the LRGB galaxies unchanged.  

Olly’s way of doing things is slightly different.  He does his adjustment on a layer underneath the main image and then uses the eraser tool to remove bits of the main image to allow the adjusted layer underneath to come through.  The result is identical to using a mask, but may be a bit quicker.  I am less confident about making catastrophic errors, even though there is PS ‘History’.  Using a mask makes it much easier for me to visualise what is going on.  A photoshop mask works identically to a PixInsight mask.  It allows you to choose the bits of an image that get adjusted.  The only difference between the PI and PS mask is that one is much easier to make than the other.

I had another go at it this morning from scratch, trying to incorporate Olly's suggestion of pulling out more of the faint structures and also using Wim's idea of deconvolution.  This might be a slight improvement.  I still resorted to PS to get rid of the Lum artefact and for one or two other tweaks, like Unsharp mask.  

6 hours ago, NigeB said:

I've had an entertaining evening reprocessing the original files following the methods described in this thread. The difference is quite amazing. My version is not up to the standards of those posted here - my stars are rather "loud" at the moment and they seem to pop out of the image. I think I can see how to tone them down - I'll work on this a bit more. I don't have PS, so I'm trying to do as much as possible in PI - although I do have Gimp...

I suspect I'm going to be working on this for several more days, but I feel like the image quality has already improved enormously thanks to your posts and is probably worth showing the delta here. So here are two versions from this evening.

Many thanks again - this has been a real revelation.

 

Both of the new versions are a huge improvement. I prefer the colours in the galaxy in the first one and the background in the second one. As you don’t have PS you could use Pixelmath to blend different versions of images - this would be one way of dialling down the effects of HDRMultiscale Transform, for example. You can make masks in PI, but it is so much easier to do it in PS that I/we rarely bother except for star masks. There are some good PI tutorials on Kayron Mercieca’s Light Vortex Astronomy site.

Hi Nigel.  Thanks for uploading the data.  I had a play with it - since we are getting nothing from home at the moment.  My workflow seems to be significantly different to yours.  I have copied what you did from your earlier thread and added my steps in yellow.  

Here are the main processing steps I applied:

1) Dark/Bias/Flatfield correction, alignment and stacking in Pixinsight using Winsorized sigma clipping.

2) Linear fit of R, G and B using L as the reference.

I/We don't do Linear fit at all and I certainly wouldn't use Lum as the reference.  When I used to do Linear Fit, I'd choose the 'darkest' of the colour frames as the reference. 

3) Applied a histogram stretch to all frames (transferring the Screen Transfer Function settings to make these permanent)

This doesn't seem right.  I would combine the RGB without stretching the individual stacks (using Channel Combination).  I would try to get the colours right before stretching.  I would do DBE to the RGB combination.  I would then do a Background Neutralization and Color Calibration.  I might do some SCNR at this stage.   I would then do the stretch.  With the RGB we tend to do a 'Masked Stretch' with the Background number set around 0.07 or 0.08.   I am just looking for nice colour at this stage, the brightness will come from the Lum.  At this point, I would check that the peaks of the histograms for the RG and B are aligned, and if not I would tweak the individual channels to achieve this.   This gives me a more balanced colour at the end.

4) Performed Dynamic Background Extraction, subtracting the resulting background frames from images to remove some gradients and a few irritating flat field issues (some remain)

Do the DBE before stretching - see above

5) LRGB Combination performed

I did a DBE on the Lum then stretched it using Histogram Transformation.  I did this in small stages.  I always do repeated iterations - drives Gnomus mad - watching the Preview - trying to keep the star sizes from getting away from me.  Once happy, I add the stretched Lum to the stretched RGB using LRGB Combination with only the Lum box ticked.  I dragged the saturation slider down to 0.36 - this boosts the saturation.  I ticked the Chrominanace Reduction box.

6) Increased saturation across the spectrum to bring out some colour. 

With the combined LRGB,  I check the histograms are still aligned and correct them again if necessary.  I do some more SCNR - the Boosted Autostretch button allows you to see if there is still some green in there.  I boosted saturation with Curves and with the Color Saturation tool - picking out the blue of the outer galaxy and the orange-yellow of the core.

7) Found that star sizes in the red image are larger than the blue and green. This was giving an excessive red tint to all stars. So I went back to the red frame, applied a star mask, followed by Morphological Transformation to reduce the red star sizes a little.

I didn't find a problem with this, since I didn't stretch the colours individually before combining them.

8) Re-did the LRGB combination + saturation increase. Found the red halo issue was helped, but not completely removed.

9) Applied a star mask and reduced saturation levels in the red channel for stars only. This removed the general red tint and brought out some colour in the stars.

10) Some adjustment of the R G and B curves and cutoffs in Histogram Transformation to try and get a colour balance in the galaxy which looked right (aesthetically).

11) Final tweak of overall RGB histogram to hide the worst of the background and achieve what looked like sensible brightness, contrast and colour balance.

I didn't do any of 8-11.  I did an HDRMultiscale Transform to a copy of the image.  Then I took the original and the HDR image into Photoshop and painted on the bits I liked.  I also did some Unsharp Mask in Photoshop.  I did find a problem with your Lum.  There was a large ring-shaped artefact extending a quarter of the way up the frame.  This is probably something to do with flats.  To be honest I didn't look at the individual subs you posted, I just used the calibrated stacks.  I 'fixed' the problem by placing the RGB only image over the LRGB one (in Photoshop again), changed the blending mode to Luminosity and painted over the artefact.         

I attach a screenshot of the odd Luminance artefact.  Then my finished image. 

5 hours ago, Zakalwe said:

I'm currently doing my National Private Pilots licence, so there may be something in this!

As Olly already knows (as we are part of his narrow sample!) both of us got our PPLs, Steve then got a night rating, an instrument rating, a commercial pilots licence in the States and even a share of a Cessna 182 before we gave up flying a few years ago.  Flying ourselves over the Grand Canyon or landing at Sedona and the international airport in Las Vegas was a complete blast and certainly beat any flying we ever did in the UK - taking off from Gamston and flying over the Humber Bridge just didn’t compete!

We just seem to have swapped one expensive weather dependent hobby for another........

1 hour ago, kirkster501 said:

So after all the work and saving to get the QSI 683 I can no longer get one.  Back Square 1.

You could probably get a new Moravian with the same chip, the external 7 position filter wheel, OAG and a whole host of new 31 mm filters for less than the cost of a new QSI!

1 hour ago, swag72 said:

The Moravian doesn't have a built in OAG, you have to buy it separate and screw it into the imaging train. That means that you'll have to work out spacing (unless someone has a bespoke adapter made)......... to me that's worth some ££'s.

The Moravian OAG is designed to give 55mm spacing when used with a Moravian camera and filter wheel - it comes with a spacer which is left in place if you have the internal filter wheel or is removed if you have the external one.  There is now a new smaller external wheel with I think 7 spaces for filters it may be less elegant than an internal wheel or the QSI but it is worth considering.

The Moravian only needs a single USB and single power supply even with the external wheel. Ours came ready assembled including the OAG from Zoltan at 365. There is a one off filter wheel set up utility that needs running but other than that it is pretty straightforward