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Night-time HDR with image stacking

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Offline fbonomi

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Re: Night-time HDR with image stacking
« Reply #10 on: 01 / August / 2008, 09:46:07 »
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For a single shot, Photoshop can handle the task well.
See for example: 
      Dark Frame Subtraction using Adobe Photoshop by Chris Limone
   

Otherwise, most of image stacking program have this option built in.
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Offline Coutts

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Re: Night-time HDR with image stacking
« Reply #11 on: 01 / August / 2008, 10:54:01 »
thanks!!
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Offline bugbear

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Re: Night-time HDR with image stacking
« Reply #12 on: 23 / January / 2009, 13:35:40 »
Quote from: fbonomi on 22 / July / 2008, 07:43:46
This is another test of night time HDR with image stacking:



More details on how I did it can be found here

I am sorry to be so late here; I found this post by googling.

I think I know a way you can process your data to get better results.

Your "base" data is 256 x 2 second exposures.

I believe that these could be processed repeatedly, with ImageStack, varying all the way from "average" to full "sum" by altering the parameters.

e.g. varying the divisor from 2,4,8,16,32,65,128

This should give a sequence where each tonal value is "well exposed" in one of the processed images.

You can then HDR stack these exposures in enfuse (or similar).

http://wiki.panotools.org/Enfuse

    BugBear
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Offline fbonomi

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Re: Night-time HDR with image stacking
« Reply #13 on: 23 / January / 2009, 15:54:03 »
yes, that's about exactly what it's all about: an HDR made on images with different divisors, the two extremes of the range being average (divisor=numer of images) and addition (divisor=1)

This case:

is result of processing in a similar way 1.350 shots of 4" each.

(the sky was processed with another algorithm to preserve the star trails of almost 4 hours )

« Last Edit: 23 / January / 2009, 15:57:38 by fbonomi »
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Offline josray

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Re: Night-time HDR with image stacking
« Reply #14 on: 24 / January / 2009, 10:44:47 »
Stunning result! Would you mind posting the workflow you follow to obtain this results?
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Offline fbonomi

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Re: Night-time HDR with image stacking
« Reply #15 on: 24 / January / 2009, 11:27:16 »
it's described rather in detail here: http://www.francescobonomi.it/index.php?foto/night-time-hdr

basically, shoot a large number of shots with a long exposure but not long enlugh to over-expose anything.

Then, stack the image (I use ImageStacker) in different ways, adding all the images together then dividing the result by a different number, ranging from 1 to "numer-of-images". Like this you will have a series of shots with a HUGE range in exposition.

Then, HDR them together.

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