I used Magic Lantern's dual iso setting to take some photos; however they cannot be correctly viewed by my software, Aftershot pro 2, until they are converted.

So far my attempts at converting the dual iso photos to RAW (for processing in photo management software) have failed. I struggled to get the software for Windows and OSX GUIs working to convert the photos.

On Linux, I haven't even tried (I use arch Linux) because you have to compile the software from scratch, I believe, regardless of the Linux distro.

I have struggled on the Magic Lantern forums as everything I have found is old.

Please could someone tell me:

  1. Where to get the software (both GUI and non-GUI versions, if available) for converting dual iso photos on 1) Windows 2) OSX 3) Linux.

  2. Detailed instructions on how to download, install and use the software for the conversion.

2 Answers 2


As the answer by inkista does not contain instructions for installation on GNU/Linux platforms, for completeness I will list the step-by-step instructions for installation on Debian-based distros (Ubuntu, Mint, Elementary, etc.) using the command line. For an OS-independent installation, I've made a simple Docker image which should work on any operating system running Docker.

The guide

First install the required packages from the repositories using apt-get:

sudo apt-get install mercurial gcc-arm-none-eabi python3-pip gcc-multilib exiftool dcraw make

Then install docutils using pip3:

pip3 install --user docutils

The --user flag is optional, but without it one usually needs root access (i.e. use sudo).

Then download the unified branch of Magic Lantern using mercurial (hg):

hg clone -r unified https://bitbucket.org/hudson/magic-lantern

Then change your directory to the following using cd:

cd magic-lantern/modules/dual_iso/

and finally build the application using make:

make cr2hdr

You should then be able to use the application by running:


If you are getting a Permission denied error, try running chmod u+x cr2hdr, and then run ./cr2hdr again. To make the application run from any directory, you can run the following:

sudo ln -s /path/to/cr2hdr /usr/local/bin/cr2hdr

where /path/to/ should be replaced with the directory where the cr2hdr file is located (to find the location of the current directory, use pwd). Altenatively, you can make an alias for the path to the application in your .bashrc file:

printf "alias cr2hdr='/path/to/cr2hdr'" >> ~/.bashrc && source ~/.bashrc

which will have a similar effect.

  • @inkista Thanks, I updated the answer now. Note that I specifically mention that the instructions above are valid for Debian-based distributions, as I use one as as daily driver, and I am not familiar enough with other distributions to be able to provide instructions or pre-reqs for those (as package names and versions can wildly vary between distributions). However, as stated above, I did provide a Docker image which should work on anything capable of running Docker.
    – JCGoran
    Aug 1, 2019 at 7:17

I'm not writing 12 separate procedures (DL-install/use x GUI/CLI x OSX/Windows/Linux). That's not a reasonable request for an SE question. I will cover using a Windows GUI. Personally, I am on OSX, and I use the Lightroom plugin for cr2hdr.

The utility you want to run the files through is cr2hdr. Links to the source code, and all the different GUI and CLI (command line interface) versions available are listed in the top post of this Magic Lantern forum thread.

  1. Download the Windows command-line .exe packages from this link: http://acoutts.com/a1ex/cr2hdr.zip

  2. Unzip the downloaded file, so you can see the separate cr2hdr.exe, dcraw.exe, and exiftool.exe files. Place them in Windows where you want them to reside.

  3. Download the BarracudaGUI installer from this link: https://bitbucket.org/0xsepa/barracudagui/downloads/

  4. Run the downloaded installer.

  5. Launch BarracudaGUI. It will ask you where you've installed cr2hdr.exe and exiftool.exe. Navigate to their install locations to specify the paths.

  6. The GUI will also ask you for a place to output the .dng processed files. Specify a path.

You are now set up. To process a .cr2 dual ISO file:

  1. Open BarracudaGUI.

  2. Click the Add CR2 files button.

  3. Navigate to where your dual iso files are, select them, and click Open.

    The files to be processed should now be listed in the main window.

  4. Click Start postprocessing.

  5. Wait until the Status window has a message that starts with *** Finish processing x file(s) where x is the number of files processed.

You now have regular DNG files to process. They will appear very underexposed--as underexposed as the specified EV interval you set. Bring the DNG file into your post-processing tool of choice, and then increase the exposure and rejoice in the lack of noise. Other common adjustments for a more "HDR-like" look might include decreasing contrast and increasing saturation.

  • Thanks inkista and is there a way of searching to find cr2 cannon raw files created using magic lanterns dual iso? I.e I have lots of other files that are normal cr2 and don't need to be processed is there a way can search for cr2 files that have a metadata property: dual iso = yes?
    – yoshiserry
    May 8, 2015 at 0:15
  • @yoshiserry I doubt it.
    – inkista
    May 8, 2015 at 0:41

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