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Using Magic Lantern => Post-processing Workflow => HDR and Dual ISO Postprocessing => Topic started by: moonlite on September 10, 2014, 10:20:00 AM

Title: two separate images from dual-iso shot?
Post by: moonlite on September 10, 2014, 10:20:00 AM
hi! i´m really in to manually merging my hdr-shots, and i´d like to do that with dual-iso shots, too.

i would like to have one image that is purely the higher iso image and one which is purely the lower iso image. is there any way to accomplish this?

thanks
Title: Re: two separate images from dual-iso shot?
Post by: Audionut on September 10, 2014, 10:26:08 AM
Dual ISO is dual line interlaced, instead of the traditional single line interlacing.

http://www.magiclantern.fm/forum/index.php?topic=12012.0
Title: Re: two separate images from dual-iso shot?
Post by: a1ex on September 10, 2014, 10:41:49 AM
Develop the DNG at two different exposures (say 0 EV and +4 EV for ISO 100/1600), then merge the jpeg's.

This script automates the task, but it usually picks more than two exposures: www.magiclantern.fm/forum/index.php?topic=7022
Title: Re: two separate images from dual-iso shot?
Post by: moonlite on September 10, 2014, 10:44:55 AM
yes, my problem is that extra information is picked up from the other image. this in my experience manifests itself as extra noise. so no tool can just give me the images completely separately?
Title: Re: two separate images from dual-iso shot?
Post by: a1ex on September 10, 2014, 10:50:18 AM
Octave, compiled with 16-bit GraphicsMagick:

Code Select

octave:1> system("dcraw -4 -E DUAL1234.CR2")
octave:2> im = imread("DUAL1234.pgm")
octave:3> a = im(1:4:end, :);
octave:4> b = im(2:4:end, :);
octave:5> c = im(3:4:end, :);
octave:6> d = im(4:4:end, :);


Or, cr2hdr --debug-blend, but the data you get from there is useful only for visual inspection, not for manual blending.
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