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Gradient reduction

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#1 pyrasanth

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Posted 24 July 2019 - 02:08 AM

I've always done my gradient reduction on the linear data being stretching and finishing off.

 

Last night I did a masked stretch on an integrated image & did the gradient reduction on the non linear data and it came out surprising well. It seemed to look visually better than applying on the linear data. I've begun to wonder now where the best stage in your imaging workflow is best for gradient reduction. The ABE and DBE seemed to produce a very nice result on the stretched data. It was as if the stretching smoothed out all the kinks so your not working with lumpy gradients all over the image allowing DBE or ABE to work somewhat better.

 

Please let me know your thoughts on this important topic.

 

Best wishes-Mark

 



#2 happylimpet

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Posted 24 July 2019 - 06:28 AM

This has been raised before and there were strong voices on both sides. I'm of the school of thought that it doesn't really matter.



#3 spokeshave

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Posted 24 July 2019 - 06:49 AM

I typically do both. The first pass at gradient reduction is linear, and I will often use more than one pass. Even so, it is not unusual for some gradient to remain that only becomes apparent after the first stretch. So I often will make another gradient reduction pass after stretching. Gradient reduction is not one of those processes that only works well in the linear state. 

 

Tim


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#4 pyrasanth

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Posted 24 July 2019 - 07:25 AM

This has been raised before and there were strong voices on both sides. I'm of the school of thought that it doesn't really matter.

My own anecdotal evidence last night suggested to the contrary. The corrections looked better on the none linear data but it could be dependent on the quality of the data being worked on. Interestingly this was probably the worse data one could get taking into account the time of the year and light polluted sky as well as limited numbers of subs per channel.


Edited by pyrasanth, 24 July 2019 - 07:26 AM.



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