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Difference between CRW and DNG files created by S3 IS

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Offline hailstorm

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Difference between CRW and DNG files created by S3 IS
« on: 28 / January / 2009, 21:44:37 »
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I took 2 shots of the same subject with CHDK latest build. one in DNG format and the other in CRW format. 2 things...when I am using DNG for powershot to convert the CRW file, the resultant DNG file is around 13mb while the CHDK produced DNG on the camera is around 7mb. Also the CRW converted DNG when opened with Adobe PS has slightly more yellow ting. Questions...

a) Is there any difference between the quality?

b) Why is there a difference in the resultant picture?


Pls help
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Offline reyalp

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Re: Difference between CRW and DNG files created by S3 IS
« Reply #1 on: 28 / January / 2009, 22:19:28 »
AFAIK dng4ps creates a 16 bit DNG. The in camera DNG is 10 bit, just like the actual sensor data and CRW.

Difference in resulting picture is probably due to different ideas about white balance etc.
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Offline PhyrePhoX

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Re: Difference between CRW and DNG files created by S3 IS
« Reply #2 on: 29 / January / 2009, 00:50:52 »
uhm, the dngs produced by dng4ps for my s3is are actually smaller than the dngs produced by camera itself - because of compression. did you turn that off?
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Offline hailstorm

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Re: Difference between CRW and DNG files created by S3 IS
« Reply #3 on: 29 / January / 2009, 01:45:17 »
yes i have turned off the compression. Does that make any diff in image quality? What is the bit depth of the dng files? I use dng for powershot. Whn i see the exif data i get "bits per sample 8 8 8". The normal jpeg shows only one 8. How to get a 12 bit output?
« Last Edit: 29 / January / 2009, 04:36:33 by hailstorm »
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Offline barfoo

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Re: Difference between CRW and DNG files created by S3 IS
« Reply #4 on: 01 / February / 2009, 14:08:40 »
Quote from: hailstorm on 29 / January / 2009, 01:45:17
yes i have turned off the compression. Does that make any diff in image quality?

It's lossless compression, so it just makes the file smaller, you don't lose any information. I've found, though, that Adobe's DNG Converter actually makes the files a bit smaller than DNS4PS.
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