The case for Adobe Digital Negative Converter

reyalp

14118

Re: The case for Adobe Digital Negative Converter

« Reply #20 on: 21 / July / 2012, 22:54:35 »

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Quote from: Mike Lee on 21 / July / 2012, 22:41:15

Adobe isn't converting any bit depth, just repackaging (and compressing) things.
...
What do you think about this?

I think it's wrong

Running with default settings on an a540 DNG, dng_validate gives the following for the converted file:

Code: [Select]

NewSubFileType: Main Image
...
BitsPerSample: 16
Compression: JPEG

Edit:
It seems to output 16 bit no matter what options I use.

I speculated earlier that converting to a lower DNG version might process the badpixel opcodes, but this doesn't appear to work. Tried setting the backward version to option 1.1. The output file does not appear to have badpixels fixed and still has the opcodes in the file. The version is set to 1.3 and backwardVersion is 1.1. The opcodes are marked minVersion 1.3.

« Last Edit: 21 / July / 2012, 23:11:56 by reyalp »

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Don't forget what the H stands for.

Mike Lee

26

Re: The case for Adobe Digital Negative Converter

« Reply #21 on: 21 / July / 2012, 23:25:12 »

Well I'll be! This I never expected, not for one minute. This is the most important thing I learned today, thanks to you! I've attached an ExifTool generated "before and after" report to show others who might also not be aware of what Adobe DNG Converter is converting. Thanks and goodnight.

16bitJPEGcompression.png (38.68 kB, 907x627 - viewed 144 times.)

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reyalp

14118

Re: The case for Adobe Digital Negative Converter

« Reply #22 on: 21 / July / 2012, 23:43:32 »

Quote from: Mike Lee on 21 / July / 2012, 23:25:12

Well I'll be! This I never expected, not for one minute. This is the most important thing I learned today, thanks to you!

FWIW, this is a perfectly reasonable thing for Adobe to do. No data is lost going from 10 to 16 bit, and when the 16 bit is compressed with lossless jpeg, the output is smaller than the original uncompressed 10 bit. Too bad we don't know how to make Digic do this for us on the camera.

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Don't forget what the H stands for.

Mike Lee

26

Re: The case for Adobe Digital Negative Converter

« Reply #23 on: 22 / July / 2012, 00:07:04 »

Oh, don't misunderstand me, I certainly agree it's reasonable, smart too, very smart. I just hadn't studied enough about DNG to know what was going on, which is a lot. Read about DNG and you find that TIFF and JPEG are mentioned a lot. Now that lossy DNG is more in the news I suspect more users and supporters of DNG will find that lossless JPEG had been implemented all along, and only now Adobe is offering a lossy variety, for greater space savings.

A good argument for DNG: http://www.digitalpreservation.gov/formats/fdd/fdd000188.shtml

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