arnoldkramer Posted March 28, 2007 Share #1 Â Posted March 28, 2007 Advertisement (gone after registration) I've noticed that if I run the 10MB DNG files coming out of the M8 through the Adobe DNG converter software that the file size drops to approximately 6MB. I cannot see what has changed, The histograms look identical. What am I missing? What is the difference between the two versions of the image file? Â Is there an earlier thread where this was discussed? I cannot find it. Â thanks Link to post Share on other sites More sharing options...
Advertisement Posted March 28, 2007 Posted March 28, 2007 Hi arnoldkramer, Take a look here Leica DNG after Adobe DNG conversion. I'm sure you'll find what you were looking for!
xrogers Posted March 28, 2007 Share #2 Â Posted March 28, 2007 It is my understanding that the Adobe converter losslessly compresses the DNG (the native format is uncompressed). This is supposed to make no difference in the data, and I have not noted any difference. Â I'd like to know if anyone out there has verified this! Â thanks, Â --clyde Link to post Share on other sites More sharing options...
Englander Posted March 28, 2007 Share #3 Â Posted March 28, 2007 In the "preferences" of the DNG converter you have a choice to compress losslessly or to not compress at all. Your choice. Â Joe Link to post Share on other sites More sharing options...
Shootist Posted March 28, 2007 Share #4 Â Posted March 28, 2007 May I ask why you are converting Leica M8 DNG files to Adobe DNG? Seems a little pointless. Link to post Share on other sites More sharing options...
bsmith Posted March 28, 2007 Share #5 Â Posted March 28, 2007 May I ask why you are converting Leica M8 DNG files to Adobe DNG? Seems a little pointless. Â Â Not if you want a full size preview in photo mechanic and other apps Link to post Share on other sites More sharing options...
fjmcsu Posted March 29, 2007 Share #6 Â Posted March 29, 2007 May I ask why you are converting Leica M8 DNG files to Adobe DNG? Seems a little pointless. Until there is full Aperture support,DNG conversion works with the plist hack ! Link to post Share on other sites More sharing options...
ho_co Posted March 29, 2007 Share #7 Â Posted March 29, 2007 Advertisement (gone after registration) Remember also, the M8's DNG includes a decode table that probably isn't necessary once the DNG has been translated into the more usual format. Eliminating that LUT would save some space, but not as much as you're reporting, since if I understand properly it consists only of 256 two-byte values. Â --HC Link to post Share on other sites More sharing options...
MarcRochkind Posted March 29, 2007 Share #8  Posted March 29, 2007 I have verified that native M8 DNGs are not compressed, and, as was noted above, you have a choice about compression when you use DNG Converter. You should always compress.  Three reasons to run an M8 DNG through DNG Converter:  1. Compressed files are safer for long-term storage, because it's more likely that you can detect corruption. Based on some tests I ran, my ImageVerifier app can detect corruption about 80% of the time in a compressed DNG, but only 20% of the time in a native M8 DNG. (Numbers are rough estimates, as they vary with the artificial "corruption" set up for the tests.)  2. You can get a full-sized preview (as noted above).  3. You can bind XMP metadata from a sidecar into the DNG, which is automated with my ImageIngester app. (This is true of DNG Converter 3.7, not of earlier versions, which ignored sidecars associated with DNGs.)  --Marc  ImageIngester.com Link to post Share on other sites More sharing options...
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