Author Topic: two separate images from dual-iso shot?  (Read 2934 times)

moonlite

  • New to the forum
  • *
  • Posts: 6
two separate images from dual-iso shot?
« 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

Audionut

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3454
  • Blunt and to the point
Re: two separate images from dual-iso shot?
« Reply #1 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

a1ex

  • Administrator
  • Hero Member
  • *****
  • Posts: 10711
  • 5D Mark Free
Re: two separate images from dual-iso shot?
« Reply #2 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

moonlite

  • New to the forum
  • *
  • Posts: 6
Re: two separate images from dual-iso shot?
« Reply #3 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?

a1ex

  • Administrator
  • Hero Member
  • *****
  • Posts: 10711
  • 5D Mark Free
Re: two separate images from dual-iso shot?
« Reply #4 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.