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  #21  
Old 13-07-2018, 04:17 PM
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Atmos (Colin)
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CLS filters can be good for emission Nebula as most of the colour comes from the Ha and OIII emissions.
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  #22  
Old 13-07-2018, 04:23 PM
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Quote:
Originally Posted by Atmos View Post
CLS filters can be good for emission Nebula as most of the colour comes from the Ha and OIII emissions.



It would still be great to get data at a really dark site & not have to use it though.
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  #23  
Old 13-07-2018, 09:11 PM
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I see, so the L filter has a larger spectrum that the RGB combination. That's problematic. It also means that the gaps in RGB will be rendered as gray in LRGB processing. It seems like they combined a light pollution filter into the RGB set, but the L filter doesn't have that gap. Curious.

But at the end, L is not a channel in an RGB image. R, G, and B are. L is used to enhance an image with weak RGB channels, because we perceive resolution in the luminance of an image, but no so much in the chrominance. But if the goal is to have the best color accuracy, then it seems better to capture correctly exposed RGB channels, and then there's no reason to capture L, right? The luminance of the image will be good, if the color channels are good. Probably add Ha capture, if the red filter cuts this important line.
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  #24  
Old 14-07-2018, 03:16 PM
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Quote:
Originally Posted by fsr View Post
I see, so the L filter has a larger spectrum that the RGB combination. That's problematic. It also means that the gaps in RGB will be rendered as gray in LRGB processing. It seems like they combined a light pollution filter into the RGB set, but the L filter doesn't have that gap. Curious.

But at the end, L is not a channel in an RGB image. R, G, and B are. L is used to enhance an image with weak RGB channels, because we perceive resolution in the luminance of an image, but no so much in the chrominance. But if the goal is to have the best color accuracy, then it seems better to capture correctly exposed RGB channels, and then there's no reason to capture L, right? The luminance of the image will be good, if the color channels are good. Probably add Ha capture, if the red filter cuts this important line.



I find that without adding Luminance to my pictures that they lack "punch".
The colours look weak.

Also - maybe since there is a crossover between some colours on all of our so called RGB filters
that perhaps we're kidding ourselves that we're viewing the correct colours?
The processing of pictures becomes subjective & open to
artistic license & a general consensus seems to build up over time
as to what a target is supposed to look like.
We then process to get similar colours.


cheers
Allan
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  #25  
Old 14-07-2018, 05:32 PM
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The only way to be certain that the images we take are accurate in terms of colour i.e the image we take = what we could see with the eye.

You would need to take some subs of a colour test card (like a colour rainbow) in low light at some distance away, stack and process and then see if the colours on the screen matches the original card that the eye sees.
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  #26  
Old 14-07-2018, 07:08 PM
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Originally Posted by billdan View Post
The only way to be certain that the images we take are accurate in terms of colour i.e the image we take = what we could see with the eye.

You would need to take some subs of a colour test card (like a colour rainbow) in low light at some distance away, stack and process and then see if the colours on the screen matches the original card that the eye sees.



Actually you could just do it with an LRGB camera
attached to an ordinary DSLR camera lens outside during the day.
Would the result look strange in terms of colour?


Anyway - notice that a DSLR camera is boosting Green - in a Bayer matrix -
by having 2 Green pixels for every Red & Blue pixel?
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