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HDR Merge file size

Comments

3 comments

  • IanS

    The dng created by C1 is similar to what happens in Lightroom when you create a pano or hdr. The hdr image is effectively a 16bit Tif image in a dng container. So for every raw pixel value you get 3 RGB values. I don't know if C1 applies any lossless compression but the file isn't likely to shrink by much.

    I normally consider these files as "temporary" work files and will output a finished jpg or Tif and then delete, as the initial hdr can be recreated from the raw.

    1
  • Boris Tomsic

    Interesting suggestion lan about deleting the HDR dng file.
    Obviously the adjustments would end up "off-line" but I guess if you need to you could could locate them to the newly generated dng file, correct?  I have been reluctant to do this as I am concerned that next time it might generate a slightly different image. I'm not 100% sure if I recall this correctly but I think that once happened with a pano stitch.

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  • Justin Burr

    Thank you for the feedback, I didn't understand how dng files worked. It's possible to use Adobe Digital Negative Converter (DNC) to further reduce file size. 

    Using C1 to export an *.arw raw file as a *.dng file increases the file size from 23.7MB to 45.8MB, although the export menu suggests exported *.dng should be 22.3MB. I thought that maybe C1 is including the original raw data in addition to the tiff inside it's exported *.dng because 23.7MB + 22.3MB = 46MB ~= 45.8MB. However, Adobe DNC could not find any original raw data inside the C1 exported *.dng file. I can use Adobe DNC to "convert" with lossless compression the C1 *.dng file to a smaller *.dng file; the file size drops from 45.8MB to 30.4MB.

    Returning to my original inquiry: Using Adobe DNC with lossless compression, I can reduce the size of the hdr merged *.dng from 137MB to 56MB. The 56MB compressed hdr merged *.dng file is still almost twice as large as the 30.4MB *.dng file.

    • Why does C1 report 22.3MB for exported *.dng and actual size is 45.7MB?
    • Does C1 use any compression when creating a *.dng file?
    • Does C1 include the original raw data inside a *.dng file?
    • Why are the hdr merged *.dng files so much larger than an exported *.dng file?
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