Save RAW files in DNG format instead of RAW - page 7 - Feature Requests - CHDK Forum
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Save RAW files in DNG format instead of RAW

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Offline Hacki

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Re: Save RAW files in DNG format instead of RAW
« Reply #60 on: 14 / November / 2008, 20:17:58 »
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- (stupid question) are you renamed files from CRW to DNG?

I tried to change the file extension, CR2, DNG, no extension at all - it makes no difference. Programs under linux dont care about the file extension anyway.

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- CHDK DNG do not contains thumbnail (at present)
- CHDK DNG is 10 bit, DNG4PS produces 16-bit DNGs
- CHDK DNG contains some errors (but dng_validate tool from Adobe shows no errors, and one warning (like DNGs from DNG4PS2)).

Ok, one or more of those may be related to my problems. I'll just stick to the original CRW files for the time being..

Thanks for the effort anyway, you're a genius!  :)
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Offline zincopal

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Re: Save RAW files in DNG format instead of RAW
« Reply #61 on: 15 / November / 2008, 06:23:00 »
If 16 bit is not DNG specification, 10 bit should be a real advantage in terms of camera processing speed without paiyng anything, infact all the compacts sensor, at this moment don't go over 10 bit of output.

Hacky you are used a sort of "synthetic"  bad pixel list, it is possible to integrate it directly in DNG process as fixed values to avoid the Sd card access ? maybe that there was a little gain of speed.
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Offline vit40

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Re: Save RAW files in DNG format instead of RAW
« Reply #62 on: 15 / November / 2008, 09:35:20 »
Quote from: ewavr on 14 / November / 2008, 16:17:47
Quote from: vit40 on 13 / November / 2008, 14:11:01
Just an idea, don't know how much programming efforts is needed for this - what about separating a dng header into external file, that will be located somewhere on the SD card, similar to headers in DNG4PS version 1?
Why not? Of course, it is possible (it's easy without EXIF tags: data/time, aperture etc.) But maybe is better to read color matrix (or someting else?) from special text file in CHDK folder.

Ewavr,

Thanks for considering that option. Of course, a "dng config" txt file would be even better, but I pressumed it would mean more programming work for you (maybe I was wrong - I didn't study the code as my programming skills are limited). In that case it should contain all camera specific tags, like color matrix, baseline noise, baseline exposure etc etc) - some of them were not configurable in DNG4PS

Another thing, I noticed there is only one color matrix in the dng. While this is perfectly valid, as dng specification doesn't require both matrices to be present, and DNG4PS2 also does the same thing is you left second matrix empty, maybe this can be cause of problems in some (crappy) programs, in case other matrix is left unitialised and causing some divide by zero error ... of course, this is only one of possible reasons

Anyway, while all this dng stuff is really a brilliant job ... sometimes increased amount of time to store a dng instead of old raw format will be a problem (especially 10, 12 MPIx sensors ...), and on the other side, I will still have to process them with Adobe Dng Converter to compress them before saving to backup ... so I'll probably stick to old raw format ... but offline dng compression would be a real benefit for me, because on several trips I runned out of space on the SD card, forgetting to take  one more card with me, as I thought one would be enough, but it turned out it wasn't ...

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Offline lrossel

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Re: Save RAW files in DNG format instead of RAW
« Reply #63 on: 15 / November / 2008, 13:52:42 »
I made a comparison between shots taken with my A720IS using the dummy badpixel.bin file attached by Ewavr in his reply #42 and a real one created with the show_bad_b.exe utility.

The difference is big when you use RawTherapee instead of Photoshop. With RawTherapee the "black dots" really are a big problem.

Here you will see the difference. The first snapshot is of a picture taken with a dummy badpixel file, and the second one belong to a picture taken with a real badpixel file.

I suggest you guys to use the show_bad_b.exe utility and use a real badpixel.bin file for your camera. It doesn't delay the CRW saving time.

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Offline vit40

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Re: Save RAW files in DNG format instead of RAW
« Reply #64 on: 15 / November / 2008, 14:31:50 »
Ehm ... can someone explain to me, why this badpixel file is needed, when raw is saved as dng, instead of "old chdk" raw format ? I remember, there was a badpixel text file before, but I never used it anyway. A these two files used for the same purpose ? Ewavr mentioned that some cameras have two badpixel files and switching from one to another at about 1/35 s.

What about video mode (my A620 is showing a bit nasty blue pixel at low light, but at daylight, it's not visible) ?

I'm a bit lost here ...
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Offline ewavr

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Re: Save RAW files in DNG format instead of RAW
« Reply #65 on: 15 / November / 2008, 16:46:40 »
Quote from: vit40 on 15 / November / 2008, 14:31:50
Ehm ... can someone explain to me, why this badpixel file is needed, when raw is saved as dng, instead of "old chdk" raw format ?
DNG specification (1.2.0.0) says: "Defective pixels should be mapped out (interpolated over) before raw data is stored as DNG."
In CHDK RAW (=saved RAW buffer) bad pixels are already marked (value=0, black level is 31 ), but not patched.
In practice, most popular freeware RAW converter DCRAW makes bad pixels interpolation, if image stored in CHDK RAW format, but no interpolation for DNG  :(
ArtDen wrote, that DNG4PS2 interpolates all pixels with value less than black level.
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I remember, there was a badpixel text file before, but I never used it anyway. A these two files used for the same purpose ?
Text file is used for patching bad pixels which are not included in internal camera list (i.e. for bad pixles, which appears after camera purchasing), binary file - for approximate copy of factory's bad pixels list .
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What about video mode (my A620 is showing a bit nasty blue pixel at low light, but at daylight, it's not visible) ?
Hmm, nobody knows how CCD data are processed in video mode.
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Offline ewavr

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Re: Save RAW files in DNG format instead of RAW
« Reply #66 on: 15 / November / 2008, 17:01:58 »
Quote from: vit40 on 15 / November / 2008, 09:35:20
... sometimes increased amount of time to store a dng instead of old raw format will be a problem (especially 10, 12 MPIx sensors ...), and on the other side, I will still have to process them with Adobe Dng Converter to compress them before saving to backup ... so I'll probably stick to old raw format...

Maybe, therefore online DNG saving is useless for most users.

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but offline dng compression would be a real benefit for me, because on several trips I runned out of space on the SD card, forgetting to take  one more card with me, as I thought one would be enough, but it turned out it wasn't ...
Hmm, I know nothing about DNG compression. Maybe is too difficult for DIGIC or not?
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Offline PhyrePhoX

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Re: Save RAW files in DNG format instead of RAW
« Reply #67 on: 15 / November / 2008, 17:17:59 »
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Maybe, therefore online DNG saving is useless for most users.

uhm, what? dng will be more useful than crw for most users - imo.
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Offline vit40

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Re: Save RAW files in DNG format instead of RAW
« Reply #68 on: 15 / November / 2008, 20:28:34 »
Of course dng is much better, as it is a standard, but just SOMETIMES longer saving times would be a problem.

Ewavr, thanks for the explanation. Are there any chances of making dng save time comparable with old raw format, say like saving a header, appending the bayer image from buffer and then fixing several exif tags and bad pixels in saved dng (this is probably a dumb question, but anyway ...)
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Offline PhyrePhoX

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Re: Save RAW files in DNG format instead of RAW
« Reply #69 on: 15 / November / 2008, 20:35:06 »
i guess if you really need the speed, use just jpg :D
and if you need raw - then use raw.
if you have an extra second or two (and dont want to use extra tools in your normal workflow, thus SAVE a lot more than just one or two seconds) - use dng.
give that man a break, he just introduced that feature and ur already asking for optimizations :D
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