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Topics - troypiggo

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General / ImageSolver using list of files not solving
« on: 2016 September 28 07:40:53 »
I'm working on a large (20 panel) mosaic and intend to use MosaicByCoordinates.  MBC doesn't seem to work unless the panels have the appropriate WCS headers, so first it seems we need to solve with ImageSolver.

ImageSolver works fine if I apply it to each of the panels using the "active window" method, but since there are 20 panels, I thought I'd try the "list of files" method instead.  However, using this method I'm getting lots of errors.  Not sure if it's user error (probably is), or a bug, or something else.

The "target image" panel of the script window appears pretty straightforward, however perhaps the issue is in the "image parameters" panel?  I have "only apply optimization" unchecked; the RA and Dec I have set to the middle of the mosaic; focal distance I've put in the focal length of my scope (506mm); and pixel size of 2x sensor pixel size because I'm doing 2x2 binning.

"Model parameters" I don't really touch from when I do individual solves - it's a local PPMX.bin file.

Any ideas?

Gallery / NGC4945 and friends
« on: 2016 June 08 21:46:36 »
Not a perfect image (bit of gradient bottom left), but am just happy to have some clear skies to image  :)
Any comments/suggestions welcomed.
Larger image on my Flickr:

Gallery / NGC4755 Jewel Box cluster and Beta Crucis
« on: 2016 June 07 14:07:40 »
I imaged this last night.  Have been experimenting with HDRComposition to control saturation of brighter stars, and Becrux is one of the brightest.  Overall I'm quite happy with the result, although the core of Becrux becomes a little funky when using MaskedStretch.  Need to experiment some more to soften the core.  I did try some CloneStamping manually, but that was a bit inelegant.

There's also some of the KAF8300 binned "bleeding" of saturated pixels (despite being HDR) because I binned the RGB 2x2.  Not as noticeable with the L being 1x1, but it is still there on close inspection.

Larger image here on my Flickr:

Update to the below:

There are some images and colour combinations that did show odd results.  Check out my post further down this thread.

Now I'm using the following formulae, just boosting G to the min of R and B.  See the link above for effects on a colour wheel showing how it much better targets just the magenta.

R: $T[0]
G: iif(min($T[0],$T[2])>$T[1],min($T[0],$T[2]),$T[1])
B: $T[2]

The attached zip file has been updated to use this formula.


Original post:

Not sure if this has been done before, but I had this idea recently on how to get rid of the magenta stars in SHO narrowband images due to the red SII and blue OIII channels needing to be stretched so much to balance strong G Ha.  A common Photoshop method I've seen is to do a selection based on colour (magenta), and desaturate it.

It occurred to me that with PixelMath we may be able to achieve something like this.  We could detect if a pixel is magenta by checking if it's R and B channels were of similar value (within some acceptable range), and if they both were significantly brighter than the G channel.

With this in mind, I came up with the following formulae.  I found some stars needed a luminance  rule in there too.

R: $T[0]
G: iif((CIEL($T)>MIN_BRIGHTNESS)||((min($T[0],$T[2])/(max($T[0],$T[2])>MAGENTA_DEFN))&&(mean($T[0],$T[2])>$T[1])),mean($T[0],$T[2]),$T[1])
B: $T[2]

Attached are some sample before and after images (not my images, but have sought the approval of the image owners where possible.  Some were from a Google image search).  Seems to work ok to me.  Thoughts?  Any improvements or suggestions on the above?

I'm just hoping it is a quick and simple solution to what seems to be a common issue with narrowband images.  Just drag and drop the attached process icon on your final narrowband image with magenta stars and they're gone.

Gallery / Lobster, Cat's Paw, and some Prawn
« on: 2014 July 25 14:39:00 »
Was going for a wider field including the Lobster and Cat's Paw nebulae. Didn't realise until processing that I also just got the Prawn in there. If I had know, I would have re-framed a bit :(

Gallery / Barnard 59 Pipe Nebula
« on: 2014 July 25 03:39:38 »
A shot I probably would never attempt with the CCD and telescope, but the 5DII sensor and 135mm focal length seemed to work for it.

Gallery / Antares, Rho Ophiuchi, and the Blue Horsehead
« on: 2014 July 24 13:55:09 »
First opportunity to image this area. Frames perfectly with the 5DII and 135L.

Gallery / Corona Australis the constellation
« on: 2014 July 24 13:53:13 »
Corona Australis.  Mostly we see the dust and reflection nebulae bottom right, but I was using my 5DII and 135L so managed to get the whole constellation.  Beautiful constellation, and easy to spot naked eye.

General / debayered images have pink stars?
« on: 2014 July 12 01:07:09 »
Doing some testing with my 5DII at home (light pollution and near full moon) before I get to a dark site next weekend.  Using Sequence Generator Pro for image capture, and have set it to capture single image (CFA fits).  I used ISO 1600 and 5min subs.  The raw subs are pretty overexposed backgrounds as per the attached image with no STF applied, and before debayering.

Using BPP and ticking the CFA option, the output debayered images have a blue background and the stars are pink.  See attached image.  I am pretty sure I've used all the correct bayer pattern settings (RGGB, VNG etc).  Tried all other combinations and all wrong.

Any ideas on the cause and cure?

General / Dark scaling different ISOs?
« on: 2014 July 11 05:22:25 »
I broke my QSI583ws :( so am currently using my Canon EOS 5DII.  I read this post by Juan, and understand that the dark scaling is not dependant on matching image times or temperatures, which is great.  Doesn't specifically confirm that ISO does or doesn't need to match, though.

I've shot a dark library at ISO 1600, 15 min subs.  Can I safely use this dark library at ISO 800 for example, or do I need to do one at ISO 800 as well?

I'm creating 2 BPP script process icons - one for 1x1 binning and one for 2x2 binning.  I believe this is necessary because I've started using Overscan and the geometry/parameters are different depending on the binning.

The bug seems to be that in the "Overscan parameters" window of the "Bias" tab, while the "Image region" parameters are correct and different in each of the 2 process icons, the "Source region" and "Target region" don't seem to be stored in the process icon, but rather remember the previous BPP overscan parameters.

  • Set up a BPP process icon BPP_1x1_template with the Overscan parameters in first screenshot
  • Set up another process icon BPP_2x2_template with parameters in the second screenshot
  • Open up the first process icon for 1x1 binning and the source and target regions carried over from the 2x2 one.  See third screenshot.  Change them to the correct 1x1 process icon settings, and the 2x2 one is now incorrect.

General / PixelMath and specifying channels - for luminance masks
« on: 2014 January 05 04:55:36 »
I am creating some PixelMath process icons for luminance mask generation.  I could first extract the Lab L channel and operate on that, but would be easier if I could just work on the lum channel directly from PixelMath.  I know $T operates on the target image, but am having trouble figuring out how to just work on the L channel.

I tried using single expression and specifying the dest colour space to be grayscale, but it didn't appear to give the same results as when I was working on L extracted from Lab.

Bug Reports / BPP ImageIntegration(?) error since update
« on: 2013 July 14 15:40:30 »
Just recently noticed there was an update to II along with some other stuff.  I updated.

Now when I run BPP, I get the error on attached screenshot.  I've also attached some of the BPP settings.

Not sure if this is something to do with the update or if I'm doing something silly.  If I do a manual II it does work.  Problem only seems to occur with BPP.

Gallery / M17 Swan Nebula L, RGB, and Ha combination
« on: 2013 May 26 13:57:58 »
Here is the best I can produce at the moment with some unprocessed data of M17 I found from last year.

I'm not advanced enough with PI to do any fancy processing.  Wish I could.  From memory, the process was:

- register, calibrate, and combine the subs;
- combine the RGB using LRGB Combination tool;
- Background Neutralisation and Colour Calibration to RGB;
- DBE to RGB;
- Masked Stretch RGB and L;
- Extract the LAB L channel from the RGB image and Linear Fit it to the L image;
- Recombine the LAB L back into the RGB;
- Combine the L image into the RGB using LRGB Comb tool (the L subs were 1x1 binned and the RGB 2x2);
- This left me with a nice looking RGB image, time to (try to) add the Ha;
- Masked Stretch and Histo Stretch the Ha;
- I had a play with the HaRGB Combination script as well as the newer and different algorithm HaRVB-AIP script.  Couldn't get a result I was happy with.  Might have a play more later;
- Ended up just using Pixel Maths using max(Ha,R) on the red channel for now; and finally
- Final saturation boost and curves adjust.

M17_HaLRGB by troypiggo, on Flickr

Been a while since I've done any image capture or processing.  Was going through some data recently and found some unprocessed M17 data.  Now I'm a bit rusty with PI.  I've processed an LRGB image (L was 1x1 bin, RGB was 2x2) and the image is below.  I've also tried to combine in the Ha (1x1) as well using the HaRGBCombination script.  But notice the bigger stars are pink?

Here are the calibrated, aligned and cropped L, Ha, and RGB FITS files for you to play with.  I'd be interested to see your process and results.

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