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Topics - dhb2206

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1
General / PixelMath Help
« on: 2019 February 15 09:36:04 »
I've noticed in my images that areas with blown out highlights after PCC have a green value that is almost half of that for red and blue, which leaves star core in linear form looking somewhat magenta. So, I was wanting to have a play with PixelMath and see if I can set a ratio for the green channel where red and blue are above a certain threshold, but I'm stumped. I've gotten as far as defining the functions for R and B as $T (admittedly that bit isn't too complex), but I have no clue as to how to refer to individual colour channels to construct my iif statement for G (IIF(myredvalue>0.85,$T/5*8,$T))?

Addendum: I suppose I could utilise a symbol definition and iterate through the individual pixels using myR = pixel($T, x, y, 0), but then we hit iteration - how does one loop through x and y from 0 to with and height respectively, or does the process just do this anyway?

I've no idea if it'll work, but no try, no know!

Cheers,

David


2
Image Processing Challenges / M42 and M43 Additional Process? #2
« on: 2019 February 11 09:40:40 »
Hmm, first post seems to have developed a fault - probably my attempt at adding a JPEG to it, so I'll give it a slot in dropbox (https://www.dropbox.com/s/mo8b9q25gg4eux3/2019-02-10-101.jpg?dl=0).

As winter is upon us in the northern hemisphere Orion is a decent target. I've been building subs for a couple of months (i.e. about 4 nights as the weather hasn't been playing ball), all with a 300mm lens attached to a Canon DSLR riding on a Skywatcher Star Tracker. There are 282 1 minute light subs at F5.6 and ISO 1600 making up the integrated image, no darks, no flats and no bias. I'd guess about 25% of these are really good quality. Anyway, I've gotten to the end of a post processing run from a drizzled integration of a square 3500 x 3500 preview and would appreciate any tips on where I may have digressed or whether there is more that could be done to improve the image.

My run consisted of:

DBE - default sample generation at a tolerance of 2, samples shunted to avoid stars and deleted where there is obvious nebulosity, reined back to 0.85 for normalised subtraction
BN
PCC
MLT (Multiscale Linear Transform) for noise on layers 1 to 4 - 3 iterations at 0.5 application and thresholds: 4, 3, 2 and 1 masked by an inverse of a lightness abstract with applied STF stretch
Morphological Transformation - Erosion of 1 on a 7 structure applied to a star mask generated from the lightness mask
Histogram Transform on highlights to even out blown out R, G and B values (following a masked stretch and pink stars!)
Masked stretch on default values with a background preview active
MLT for noise stepped back on thresholds to 3, 2, 1, 0.5 masked by lightness extract auto clipped for shadows and highlights
ACDNR on defaults
Histogram Transform to reset black point with minimal clipping
Curves Transform - tiny tweak of RGB for contrast and a reasonable saturation increase
HDRMT (HDR Multiscale Transform) at 9 layers to lightness on a mask revealing just the core of M42

I'm pretty chuffed with the result though the jpeg doesn't do it justice (if I can get it to attach).....

I've stuck the files in a dropbox in case anyone fancies a play, but be aware, the files are large (575MB each)!

Base drizzle image is here: https://www.dropbox.com/s/vrcamdn8pqjwyn3/190210%20Drizzle.zip?dl=0
Post processed image is here: https://www.dropbox.com/s/kfdhzzhoqd9m54s/190210%20Drizzle%20Post%20Plus.zip?dl=0

3
Image Processing Challenges / M42 and M43 Additional Process?
« on: 2019 February 11 08:09:12 »
As winter is upon us in the northern hemisphere Orion is a decent target. I've been building subs for a couple of months (i.e. about 4 nights as the weather hasn't been playing ball), all with a 300mm lens attached to a Canon DSLR riding on a Skywatcher Star Tracker. There are 282 1 minute light subs at F5.6 and ISO 1600 making up the integrated image, no darks, no flats and no bias. I'd guess about 25% of these are really good quality. Anyway, I've gotten to the end of a post processing run from a drizzled integration of a square 3500 x 3500 preview and would appreciate any tips on where I may have digressed or whether there is more that could be done to improve the image.

My run consisted of:

DBE - default sample generation at a tolerance of 2, samples shunted to avoid stars and deleted where there is obvious nebulosity, reigned back to 0.85 for normalised subtraction
BN
PCC
MLT (Multiscale Linear Transform) for noise on layers 1 to 4 - 3 iterations at 0.5 application and thresholds: 4, 3, 2 and 1 masked by an inverse of a lightness abstract with applied STF stretch
Morphological Transformation - Erosion of 1 on a 7 structure applied to a star mask generated from the lightness mask
Histogram Transform on highlights to even out blown out R, G and B values (following a masked stretch and pink stars!)
Masked stretch on default values with a background preview active
MLT for noise stepped back on thresholds to 3, 2, 1, 0.5 masked by lightness extract auto clipped for shadows and highlights
ACDNR on defaults
Histogram Tranform to reset black point with minimal clipping
Curves Transform - tiny tweak of RGB for contrast and a reasonable saturation increase
HDRMT (HDR Mutiscal Transform) at 9 layers to lightness on a mask revealing just the core of M42

I'm pretty chuffed with the result though the jpeg doesn't do it justice (if I can get it to attach).....

I've stuck the files in a dropbox in case anyone fancies a play, but be aware, the files are large (575MB each)!

Base drizzle image is here: https://www.dropbox.com/s/vrcamdn8pqjwyn3/190210%20Drizzle.zip?dl=0
Post processed image is here: https://www.dropbox.com/s/kfdhzzhoqd9m54s/190210%20Drizzle%20Post%20Plus.zip?dl=0

4
Bug Reports / Crash on Debayer
« on: 2019 February 04 00:32:41 »
Since the new update I've been finding that my first attempt at a debayer will crash PI completely; a wipe out - no error messages, just gone. Second time round it works fine. I'm debayering from a Canon 760d in CR2 format set for RGGB to VNG (I used to get a similar behaviour if I left the pattern dropdown on Auto in the previous version, but just for this camera, the 100d was fine to leave on auto).

Not a prohibitve bug, just slightly irritating when you forget it is coming!

Cheers,

David

5
General / Getting the best from a JPEG export
« on: 2019 January 26 00:52:15 »
I'm probably just doing something wrong here, but whenever I export to JPEG I lose a serious amount of detail and the image darkens substantially. I have a feeling it is a difference in colour space between monitor and JPEG that is causing the issue, but I haven't a clue how to solve it. And, yes, I know that JPEG compresses the image, but I shouldn't get better results from a simple screen grab!

Help please.... :-)

PS Export to PNG works far better.

6
Bug Reports / Image Integration Fails to use FITS Keyword
« on: 2018 December 30 02:14:20 »
I've had a couple of goes at bringing in a keyword from the new subframe selector process, but integration fails to pick these up. See screenshot - keyword is embedded but an error is triggered.

7
General / Setting Process Defaults
« on: 2018 December 28 15:32:02 »
This probably exists and I just haven't come across the answer.

Can you set the defaults for the various processes?

I have a terrible habit of forgetting to check the drizzle box at registration and always realise just before the second or third last frame has gone through the mill......

8
Bug Reports / Unusual Results from Photometric Colour Calibration
« on: 2018 November 09 00:04:06 »
The image: https://www.dropbox.com/s/nxtxzgrntx8afj8/181108%20Drizzle.zip?dl=0

I've come across some rather strange happenings with one image in particular, it is certainly nothing special, but thought this merited a post. I'm using just a DSLR and camera lenses at present and shortcutting all over the place as well as experimenting. So this time I was seeing whether my skytracker would cope with two minute exposures, the answer was "sort of" - 50% of the exposure went in the bin. Anyway, I digress. I followed my usual workflow; debayer, register, integrate, drizzle integrate, DBE, BN and I come to PCC. I ran PCC without a solved image and wound up with a very red result with white balance and background readings of:
* Color transformation functions:
R-G = +9.740790e-01 + 8.713840e-01*(Sr-JV) ± 4.639148e-02
B-G = +2.756727e-01 + 4.287585e-01*(JB-JV) ± 4.129395e-02
* White balance factors:
W_R : 1.0000e+00
W_G : 4.8952e-01
W_B : 8.3530e-01
Applying white balance: done
Evaluating background reference: done
* Background reference:
B_R : 9.16751e-05
B_G : 5.58175e-02
B_B : 9.53854e-02
Applying background neutralization: done
02:53.94

So, red is obviously very wrong and I undid PCC.

Run #2 I plate solved first for M45, no problem (Focal 171.53 and Pixels at 1.9). Then ran PCC again but received a very blue image this time (note that I suppressed the saturation threshold to 0.8 in this run) and received:
* Color transformation functions:
R-G = +3.833681e-01 - 9.225998e-01*(Sr-JV) ± 5.962888e-02
B-G = +1.069563e+00 - 3.878159e-01*(JB-JV) ± 4.107895e-02
* White balance factors:
W_R : 8.3131e-01
W_G : 4.8125e-01
W_B : 1.0000e+00
Applying white balance: done
Evaluating background reference: done
* Background reference:
B_R : 9.50452e-02
B_G : 5.47973e-02
B_B : 9.64830e-04
Applying background neutralization: done
02:27.95

This time blue is very obviously wrong.

How do I fix this one?

Cheers,

David

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