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Author Topic: What part of the DNG standard allows this to work?  (Read 2007 times)

ashaughnessy

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What part of the DNG standard allows this to work?
« on: January 15, 2013, 09:46:18 AM »

On my Pentax K20D, shooting in raw mode, I can still select certain scene preferences - e.g. "natural", "bright", "landscape", "portrait", and "Monochrome". Choosing one of these changes the way the image is shown in the in-camera display, but it also carries over to the Pentax raw conversion software, which also shows the raw image using this preference. I.e. choosing monochrome at time of shooting shows you the picture in black and white all the way through the workflow. Note however that the full colour information is still there, as within the pentax raw software I can choose any other scene mode after downloading and choose one of the colour modes instead.

The question is - I also get the benefit of this in a third party piece of free software I use for picture cataloguing - "My Photo Index". This understands DNG raw files but it also seems to honour the scene mode setting, so that pictures shot using the Monochrome scene mode are displayed in My Photo Index in monochrome.

Assuming that My Photo Index doesn't have any special built-in knowledge of the K20D, this presumably means there is something in the DNG raw file standard that allows such scene preferences to be stored in the file as meta-data. Anyone know about this and how it works? It's a very handy feature.

Thanks
Anthony
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EduPerez

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Re: What part of the DNG standard allows this to work?
« Reply #1 on: January 15, 2013, 10:07:16 AM »

RAW files can contain both the raw data and a small JPEG version, used for fast extraction of thumbnails; most likely, your camera is applying your scene preferences to the thumbnail, and "My Photo Index" is using that thumbnail too.
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ashaughnessy

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Re: What part of the DNG standard allows this to work?
« Reply #2 on: January 15, 2013, 10:13:27 AM »

I thought of that, but the My Photo Index software can show the raw image in sizes up to around about six hundred pixels on the long side (guesstimate), which seems large for an embedded thumbnail image. You might be right though.
Anthony
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afx

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Re: What part of the DNG standard allows this to work?
« Reply #3 on: January 15, 2013, 10:18:13 AM »

I thought of that, but the My Photo Index software can show the raw image in sizes up to around about six hundred pixels on the long side (guesstimate), which seems large for an embedded thumbnail image. You might be right though.
Typical raw files have a full size JPG embedded. Why wouldn't Pentax do the same with DNG?

cheers
afx

ashaughnessy

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Re: What part of the DNG standard allows this to work?
« Reply #4 on: January 15, 2013, 10:21:31 AM »

Thanks, that sounds like the answer then - no magic, just an embedded jpeg.
Anthony
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Tim Lookingbill

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Re: What part of the DNG standard allows this to work?
« Reply #5 on: January 15, 2013, 04:07:44 PM »

Typical raw files have a full size JPG embedded. Why wouldn't Pentax do the same with DNG?

cheers
afx

Instant Jpeg From Raw allows a full size 6MP 3000x2000 jpeg to be extracted out of my Pentax K100D PEF. I never tried it on a converted DNG or Pentax source DNG because I've never needed to convert to or use that format except for camera profiling. Give it a try...

http://michaeltapesdesign.com/instant-jpeg-from-raw.html
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