Battling light pollution

Comments

• BlockHead

  July 2022 edited July 2022

  Hi Brian,

  
  

  A light polluted image is one that has a bright background with elevated sky counts. When the moon is in the sky, this is a form of light pollution. Many imagers have other issues in addition to the light pollution.

  So, if you have a good example i will gladly take a look. However, please be prepared to support the argument it is just light pollution and not other causes. 

  
  

  -the Blockhead
• Brian Maynard

  July 2022

  I certainly won't argue my images suffer from a multitude of problems. I've been imaging a long time but I'm not the sharpest tool in the shed. I've never been able to process by the numbers or analyze anything to the degree that's needed to really know whats going on. Light pollution, I believe, is the biggest problem but I'd be very interested on your expertise on my entire imaging workflow. I've attached and image that is straight out of WBPP and the final image here   LDN 673 (BrianMaynard) - Full resolution | AstroBin   This is a particularly difficult image because of the bright background of stars. DBE takes care of gradients but seems to wipeout the background color that should be there in this image. Let me know what you think. I have the entire image files I used ready to be analyzed  : )  

  

  

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• BlockHead

  July 2022

  Hi Brian,

  
  

  With regards to light pollution let's talk about the statement you said above that applies:

  
  

  " DBE takes care of gradients but seems to wipeout the background color that should be there in this image. "

  
  

  I think this is a very good point you have raised here. First, in looking at your final result- I would say it looks great and there is little evidence you imaged this from a light polluted sky. However, you are certainly correct that DBE *will* remove color from the dust clouds. Whatever color is there, which is likely a small signal, is THE SAME BRIGHTNESS AS YOUR SKY. When you use DBE, you are identifying a background level. Thus any adjustments to your light pollution will *necessarily* impact the color of the dust clouds also. And the clouds simply may be colored more strongly by the bright light polluted sky. They are co-mingled and inseparable in your data. Period. You want that dust cloud color to remain after applying DBE? You have to go to a darker site. This is the point. There are real implications of imaging from a brighter site. There is nothing that Adam Block or anyone else can do about this *numerically.* Now... you might point at some images that others have taken using similar equipment and similar conditions- and have more color. It could be differences in data or conditions- but more often than not- the imager has arbitrarily adjusted the color to make it pleasing.

  
  

  This aspect- is not what I want (or need) to show. You believe the color should be there. During the day I believe the stars are still in the sky even though all I see is bright blue. But there is no picture I can take in the daytime that gives me a sky full of stars...I need to wait for the sun to set.

  
  

  Finally, based on your simply integrated image- it could be there is an optimization (improvement) you could achieve in flat fielding that would require DBE to do less- and thereby perhaps achieve better color fidelity in your data. But... that is an acquisition issue that would need to be investigated (it isn't a workflow or processing issue).

  
  

  Let me know what you think.

  -the Blockhead 
• Brian Maynard

  July 2022

  Thanks Adam. You are right. I'll likely never have that dark sky remote setup but I love the hobby. I'm also very appreciative of people, like yourself, who contribute so much of their time. 

  
  

  One last go at processing LDN673. I think I got some better background color by "Using DBE creatively"  : )
  

  
  

  
  

  
  

  
  

  
  

  
  

  

  

  Image20.jpg

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