Adobe DNG Converter with M8 dng files

[Stan Raucher]

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I've been looking at the results from using Adobe DNG Converter (v3.4x89) on M8 dng files.

 

If I start with an original Leica 10.3Mb M8 dng file and process it with Adobe DNG Converter with the following preferences: "JPEG Preview: Full or Medium Size; Compression: Compressed (lossless); Preserve Raw Image", I get a new dng file that is approximately 5.8 Mb (the file is a little bigger with a large vs a medium embedded jpg). If I open both the original Leica dng file and the converted dng file using ACR in Photoshop CS2, the two files appear to be identical with respect to their histograms. Any post-processing of these files with curves, levels, etc. also gives me identical results when the histograms are compared. Saving these dng files in Photoshop as 16-bit PSD or TIF also gives what appear to be identical files which are, of course, the same size.

 

So, what exactly is happening to the original Leica dng file when it is processed with Adobe DNG converter? It's suppose to be a lossless conversion and indeed appears to be so. I certainly would like to cut the storage size of my dng files by nearly 50% if I'm not losing anything.

 

Also, the converted dng files may be more "universal" regarding their use with other programs or devices than the original Leica dng files. I reached this conclusion based on results with my Epson P-5000 Storage Viewer. In particular, although my Epson P-5000 can not display original Leica dng files, it will display the Adobe converted dng files with embedded large or medium jpgs. The P-5000 won't display Adobe converted dng file if the preference were set to "JPEG preview:none" during the conversion.

 

Any comments from those of you who know how Adobe DNG converter works would be appreciated.

 

Thanks,

 

Stan

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[Guest sirvine]

On your last point there, wouldn't your Epson just be displaying the JPEG? That would explain why it has no preview where you've only provided it with the RAW/DNG files.

[stunsworth]

Stan my understanding is that the lossless compression is just that. In effect you're 'zipping up' the DNG file. A similar thing happens with Canon RAW files that are compressed automatically by the camera. This gives varying sizes depending on how efficiently the image can be compressed.

 

I've no idea why the Epson will only display DNGs with large embedded Jpegs, other than the fact that the M8 embeds a small Jpeg and perhaps that's not large enough to display. In fact I would be very happy if the Jpeg embedded in the M8's DNG file was full sized. It would solve problems I have in other areas.

[Stan Raucher]

The Epson-P5000 doesn't recognize the embedded jpeg in the original Leica dng file, but it does recognize the embedded jpeg from the converted dng file. The P-5000 is not reading the actual raw file. It doesn't matter if you do the conversion to embed a large or medium sized jpeg - the size of the image on the P-5000 is the same.

 

In any case, I think that I will run my Leica dng files through Adobe DNG converter with lossless compression as a first step in my workflow to save storage space. This will also allow me to rename my files at the same time that I do the conversion.

 

If you haven't tried the Adobe DNG converter, it's worth a look.

 

Stan

[Guest sirvine]

Has anyone noticed whether Lightroom does the same kind of compression when you import M8 files? I wonder if it converts M8 DNGs to these more compressed DNGs (yuck) automatically?

[teehas53]

Be aware that M8 files re-processed through the DNG converter CANNOT be viewed or worked on by any current version of Capture One. They cannot be "converted back" either. You will be locked out of C1 for those files.

 

Whether this is a temporary bug, or a deeper-level C1 / DNG incompatibility is currently not known (by me at least... )

 

I posted a thread on this topic a while back, and not a peep out of anyone at Phase One.

 

Tom