Converting Raw to DNG and DNG is larger?

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pgallett

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I've been testing Raw to DNG conversions and I'm having a few issues.

First, the converted DNG file is 1'mb larger than the raw (18.9mb vs 29.4mb). The raw file is mRaw if that makes a difference, but I assumed the file size of the DNG would scale with the file size of the RAW. I am generating the jpg preview, but I have a hard time believing that would chew up another 1'mb. Is this just the nature of the beast? I had been expecting the 2'% space savings I've seen posted around.

My conversion settings are attached.

Secondly, I'm getting an error "An error occurred while converting 'filename'" Failed to delete the original photo file.
The DNG is successfully created and replaces the raw in the catalog. My files are on a NAS, but I have never had permission issues deleting from LR.

Thanks in advance.
 
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What camera are you using to create the mRAW? What happens if you convert to DNG during import rather than after import?
 
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You got me thinking. I went back a bit further and converted a raw from a Canon 2'D and it is smaller than the DNG (8.4 -> 7.3). Maybe it's something with the mRaw format? I still get the import error btw.

Thanks
 
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I don't have a 7D with which to test but I am seeing that a 5D MKII RAW file is 22.9 MB in size. A sRAW1 is 13.1 MB. When I convert the sRAW1 to DNG it comes out 23.5 MB-doubles in size. This looks buggish to me. I am going to test in the LR 3 Public beta and see what results.
 
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I see the problem in the LR Public Beta as well. Also, it manifests in Adobe's DNG Converter 5.6 as well. I will fill out a bug report on the issue.
 
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That's not a bug. mRAW and sRAW are not true raw files - they're already demosaiced in the camera. There's nothing in the DNG spec to support the native image format used by sRAW so the conversion to DNG requires producing a three-channel demosaiced RGB image, which is much larger.
 
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Interesting, Victoria. I wasn't aware of that.
 
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It took me ages to get my head round it too Rikk, and I can still never remember the technicalities.
 
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