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Save RAW files in DNG format instead of RAW

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Offline mx3

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Save RAW files in DNG format instead of RAW
« on: 13 / December / 2007, 02:34:47 »
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is it possible to save RAW files in DNG format?

options:
1) do not save JPG ( Q: how to view them in camera? )
 it seems it is optional.
 we can select to make photos in 640x480 with bad jpg compression - for in cam review
 RAW file will be in max resolution  anyway

2) compressed DNG ( slower )

benefits:
1) no need to convert files
2) no problems with custom EXIF data (?)
3) no problems with new camera models (?)


« Last Edit: 13 / December / 2007, 02:45:17 by mx3 »
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Offline GrAnd

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Re: Save RAW files in DNG format instead of RAW
« Reply #1 on: 13 / December / 2007, 02:54:42 »
is it possible to save RAW files in DNG format?
If do not compress, files will be 50% larger than now.
If compress, the time for saving will be increased to 10 seconds, I guess.
The both ways are not acceptable.
CHDK Developer.

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Offline mx3

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Re: Save RAW files in DNG format instead of RAW
« Reply #2 on: 13 / December / 2007, 03:11:35 »
is it possible to save RAW files in DNG format?
If do not compress, files will be 50% larger than now.
If compress, the time for saving will be increased to 10 seconds, I guess.
The both ways are not acceptable.

I'm sure some people will not agree with you

just checked:
it takes 5 seconds for my camera(a630+ts2gsdc card) to save files ( 10mb raw + 3,6mb jpg)

lets assume size will be 15 mb for dng + 50kb JPG
I don't see big difference

it is also possible (?) that compression time will be less than SD card write operation
why not to check?
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Offline GrAnd

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Re: Save RAW files in DNG format instead of RAW
« Reply #3 on: 13 / December / 2007, 03:15:20 »
just checked:
it takes 5 seconds for my camera(a630+ts2gsdc card) to save files ( 10mb raw + 3,6mb jpg)
5 seconds for conversion with compression? Have you already implemented it?
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Offline mx3

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Re: Save RAW files in DNG format instead of RAW
« Reply #4 on: 13 / December / 2007, 04:03:17 »
5 seconds for conversion with compression?
no.
it is time for original build which saves RAW files

Have you already implemented it?
no.

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Offline GrAnd

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Re: Save RAW files in DNG format instead of RAW
« Reply #5 on: 13 / December / 2007, 05:52:56 »
5 seconds for conversion with compression?
no.
it is time for original build which saves RAW files
I have the time less than a second for saving ~6.5M RAW with ~2.2M JPEG files. You have to try more faster SD-card.
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Offline a710is

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Re: Save RAW files in DNG format instead of RAW
« Reply #6 on: 13 / December / 2007, 05:57:43 »
my cam also saves raw and jpeg in about a sec. I have an OCZ 150x and a Corsair 133x (the Corsair is a bit faster though - 9 MB/s vs 9.5 MB/s

Re: Save RAW files in DNG format instead of RAW
« Reply #7 on: 11 / April / 2008, 12:32:43 »
is it possible to save RAW files in DNG format?
If do not compress, files will be 50% larger than now.
If compress, the time for saving will be increased to 10 seconds, I guess.
The both ways are not acceptable.
Hi, I have a small question regarding Your assumptions.
From what I've seen in the TIFF/EP and DNG standards, these allow 10bit per sample and it is not mandatory to pad the sample to the 16 bit boundary. The only mandatory thing is to pad each end of the row to the 8it boundary. And from what I've seen, the row sizes are set so this is true without padding.

To summarize, it seems to be possible to achieve basic DNG compatibility (without the preview) just adding a proper header before unaltered raw stream of data from the camera.
Am I right?

Kind regards.


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Offline wontolla

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Re: Save RAW files in DNG format instead of RAW
« Reply #8 on: 11 / April / 2008, 13:59:56 »
Simple compression algorithms won't work on this kind of file.  There are no big chunks of similar information (like in text) so there won't be noticeable compression (the file could even grow!).

More elaborate algorithms will take long time to execute. Even more time than saving the "50% larger than now".

The fact that DNG4PS2 converts a file in 0.5 seconds (on my PC) gives a hint on how much time the camera's processor will need to complete the task.

I hope I am totally wrong and someone comes up with DNGs straight from camera. I'd like to help on this but muy problem is that I think it is hopeless.

May be ArtDen can give some input here.

Re: Save RAW files in DNG format instead of RAW
« Reply #9 on: 11 / April / 2008, 14:10:13 »
wontolla: I do understand Your point.
The thing I wrote about is that it seems, that the basic DNG support with uncompressed data should take very little more space than the actual RAW data. That is, the only thing needed would be a proper DNG header. I do hope i'm right here...

 

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