Why aren't my colour images as good as my mono images?

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ram United States of America
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Why aren't my colour images as good as my mono images?

#1

Post by ram »


Hi all, I think my handling of colour while making NB images still could use some improvement. I am quite happy with my mono image processing but then when I combine things, it starts to go down hill.

Take a look at this image, which I think is one of the best of the target I'm working on. I have data that's pretty similar to this when I look at the mono images and my O3 data IMO is significantly better. Yet when I put it all together, I don't get that beautiful combination he gets, and in particular, check out the texture of the Ha data.

https://apod.nasa.gov/apod/image/1610/S ... singer.jpg

Here's where I'm at and I still need to work a bit more on this (the O3 is actually the old data at half the drizzled resolution since I've not finished processing it at this resolution yet) but hopefully you can see my attempts at getting the texture and lighting:
Image61.resized.jpg
My mono images DO look better (texture, etc. which is either very similar or some other choices I've made I'm happy with). But my colour images don't retain that same texture, which looks flat and not like a painting. On top of it I think this image does some tricks to get a 3D like effect but I can't be sure so I can try some of that but still, the texture is missing (or maybe it is due to the 3D effect - I have to try this out - this is basically like using your data to create like a topographic/relief map so perhaps that's what is adding that texture).

Hmm. I am blind in one eye, I wonder if that makes a difference. My daughter said that what I look at as raised she sees as depressed.

--Ram
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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Re: Why aren't my colour images as good as my mono images?

#2

Post by bradleybcraig »


Hi Ram!

Color looks great, still some background gradient. Otherwise it's a really nice image. For texture or contrast and detail how are you creating a Luminance layer? This is where you'll effectively achieve what you looking to improve. Let's start there. Do you create a specific Luminance image separately to process or are you just combining narrowband and processing or attempting process details with the color image?
-Brad

Hardware: Meade 8" ACF, Mallincam CF VRC-8 & 0.75 reducer w/ Moonlite 2" CS focuser & High Res Stepper, WO Star 71 w/ Moonlite High Res Stepper,
iOptron CEM60, Modified Canon 450D, Atik 383L+ mono, Lodestar X2, 2" Atik EFW2, Astrodon 36mm 3nm NB Ha/Sii/Oiii Filters, LRGB Gen2 E-Series Tru-Balance Filters, PoleMaster
Software: SkySafari Pro, Sequence Generator Pro, PHD2, PixInsight
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Re: Why aren't my colour images as good as my mono images?

#3

Post by ram »


Hi Brad, thanks for responding! No, I'm not creating a luminance layer - it's just Ha, O3, and S2. Sometimes I do use a synthetic L but in this case I'm using a complex formula to generate these colours using PixelMath and I didn't account for the L channel. The SHO native doesn't look good IMO (i.e., straight channel combination looks worse than this). So this is one of the formulae I'm using (the one that generated the above image). Basically Ha and S2 go into red and then I highlight certain aspects of Ha and S2 using the green channel using a quadratic equation.

R: 2*Ha+1.5*S2
G: Ha^4+S2^2+0.5*O3+0.3*S2
B: 3*O3

I've not done any processing after colour combining - I did all of it before and the mono images look great so I'm wonder why that texture and such doesn't carry over (what I see in individual images gets smooshed out after colour combination, even if I just use Ha only data for instance). I can do further processing and get back some of it but I wonder if that's the right way to do it.

--Ram
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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Re: Why aren't my colour images as good as my mono images?

#4

Post by bradleybcraig »


Hi Ram!

So if you extract the Luminance channel from your color image using ChannelExtraction and look at it, how does it compare to your mono channel images? So in general, regardless of processing a color RGB or color narrowband image the details will always be dictated by the Luminance channel. In narrowband it's pretty common to derive a synthetic Luminance channel. Whatever pixel math combination that works for color may not always be best for luminance. For instance, I usually amass significantly more integration time on Ha than I do on Sii or Oiii. Therefore my Luminance is usually a processed version of the Ha image. If Sii or Oiii are significantly more noisy, then using it in Luminance can destroy details. Regardless of what makes up a synthetic Luminance, focusing processing on that separately from color processing is the way to go.
-Brad

Hardware: Meade 8" ACF, Mallincam CF VRC-8 & 0.75 reducer w/ Moonlite 2" CS focuser & High Res Stepper, WO Star 71 w/ Moonlite High Res Stepper,
iOptron CEM60, Modified Canon 450D, Atik 383L+ mono, Lodestar X2, 2" Atik EFW2, Astrodon 36mm 3nm NB Ha/Sii/Oiii Filters, LRGB Gen2 E-Series Tru-Balance Filters, PoleMaster
Software: SkySafari Pro, Sequence Generator Pro, PHD2, PixInsight
Astrobin: https://www.astrobin.com/users/a028964/
Flickr: https://www.flickr.com/photos/bradleycr ... roimaging/
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Re: Why aren't my colour images as good as my mono images?

#5

Post by yobbo89 »


there's so many variables in this hobby .. i think he is using a 10 micron mount and 1000mmfl refractor and most likely a very dark site. you can see that he used deconvolution a bit in his image ..

looks he used rgb stars and probably hue shifted the squid to the lighter teal blue colour ..

do you process your mono images first then lrgb combine ?

can we have at look at your data?, i can pm to stop any spoils
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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Re: Why aren't my colour images as good as my mono images?

#6

Post by bradleybcraig »


Here's proof of what you can do, unfortunately it's not the how as that's a whole other set of videos and I don't have any, but youtube is full of them ...

https://youtu.be/5ALLDQTBsSA
-Brad

Hardware: Meade 8" ACF, Mallincam CF VRC-8 & 0.75 reducer w/ Moonlite 2" CS focuser & High Res Stepper, WO Star 71 w/ Moonlite High Res Stepper,
iOptron CEM60, Modified Canon 450D, Atik 383L+ mono, Lodestar X2, 2" Atik EFW2, Astrodon 36mm 3nm NB Ha/Sii/Oiii Filters, LRGB Gen2 E-Series Tru-Balance Filters, PoleMaster
Software: SkySafari Pro, Sequence Generator Pro, PHD2, PixInsight
Astrobin: https://www.astrobin.com/users/a028964/
Flickr: https://www.flickr.com/photos/bradleycr ... roimaging/
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Re: Why aren't my colour images as good as my mono images?

#7

Post by ram »


Hi Brad, thanks - when I extract the L it's not bad but it's not as good the individual mono channels. It seems to be somewhere in between. But maybe you're right - I should just the Ha only data and see how it looks. I thought I could combine the Ha and S2 data but there's a lot of fine detail in these channels that are getting lost when the colour image is made. It's visible to a greater extent in the L data (perhaps that's due to black and white?) but it's not the same. But I think I'll try your idea---work in mono entirely and then colour combine and I should have the resulting texture is what you're saying, right?
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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Re: Why aren't my colour images as good as my mono images?

#8

Post by ram »


Hi Yobbo, yes, I plan to put in the RGB stars and deal with the Squid if needed later. I'm not at the end of the processing yet (I plan to go starless and then do more and come back with RGB stars but I'm wondering if I can't get more out of the mono images before I colour combine or just right after, like for instance trying out the idea mentioned by Brad). I'm mainly referring to the red colour and the depth that comes it so ignoring the blue/squid is fine since what I put in is a half the size of the other two, so it's acting like a placeholder.

Here're the links to the current versions of the XISF files - let me know if you want the starting points (it takes a while to upload each one). The O3 data is at a different resolution than the other two.

http://ram.org/images/space/downloads/o ... 1_l_d.xisf
http://ram.org/images/space/downloads/o ... 6_480.xisf
http://ram.org/images/space/downloads/o ... 1_l_d.xisf

No worries, you can respond to this thread - it's free information as far as I'm concerned.

I think my point is independent of the gear used: I am able to get the kind of detail I want in the mono images but not in the colour ones but I think Brad's approach of creating a L channel in mono the way I want it and then just doing the LRGB combine may be worth trying.

--Ram
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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Re: Why aren't my colour images as good as my mono images?

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Post by STEVE333 »


bradleybcraig wrote: Mon Oct 19, 2020 1:15 pm Here's proof of what you can do, unfortunately it's not the how as that's a whole other set of videos and I don't have any, but youtube is full of them ...

https://youtu.be/5ALLDQTBsSA

Thanks so much for the tip and video "proof" Brad, much appreciated.

So much to learn about this wonderful hobby.

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight ***** My AP website: www.steveking.pictures
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Re: Why aren't my colour images as good as my mono images?

#10

Post by ram »


Brad, I just took a look at your video since it was so short (I won't be able to work on this anymore until the 30th anyway since I have a deadline, so.).

So would you advocate doing what you seemed to do in that video, take out the L and then clean it up and then put it back as the L for colour combination? OR create a separate L from PixelMath combinations of the mono images and then colour combine? For instance, if my Ha image looks great, and if I use that as a L, that should be an equivalent outcome, right? Or do I have to use the L extracted from the first combination for best results?

Did you use LRGBcombination to recombine again? One of the reasons I combine with 3 colours is so I can use PixelMath to combine. But maybe there's a way to reference specific colours with a single PixelMath equation...

--

Yobbo, did you have a chance to play with the data?

--Ram
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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Re: Why aren't my colour images as good as my mono images?

#11

Post by yobbo89 »


what did you do to the data prior uploading ? it seems drizzled and streatched alot,ha and sii 2x2 binned ?, i had a hard time trying to cut out the background , ie clipping it to black .

i didn't do anything fancy, no deconvolution, just not enough signal to go gun ho sharpening . this is oiii as lum and hoo as rgb . the sii and with all the channels background lifted just added too much noise .i think we have to try and cut down the background and try to get your image to pop in colour and detail
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TEST SQUID.jpg
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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Re: Why aren't my colour images as good as my mono images?

#12

Post by ram »


Drizzled, LocalNormalization, and it is not 2x2 for Ha, S2, unless you mean 2x. It's the Drizzle scale - it upscales things so the default is 2x. This was all processed though, so finished with deconvolution, denoising, soft stretch, etc. I gave you this version since the problem I was having was the colour combination - I am really happy with the mono images.

Only the O3 is the 2x2 equivalent which is why I said it's a placeholder - it's the older data from when I was doing it separately. I haven't finished with the 2x O3 data. It looks nice in your image. :)

I agree, we should combine the Ha and S2 in a clever way first.

--Ram
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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Re: Why aren't my colour images as good as my mono images?

#13

Post by STEVE333 »


Ram - I just watched a YouTube tutorial on how to make Blue "Pop" in a BiColor (HOO) image. Part of the tutorial showed how to use the Luminance to sharpen the image. I was amazed at how well it works. You might be able to use this approach for getting the sharpness back into your NB color images. The link is below:

https://youtu.be/5M3zB7-Llhw

Hope it helps.

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight ***** My AP website: www.steveking.pictures
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