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Posts: 5,028 | Thanked: 8,613 times | Joined on Mar 2011
#611
Originally Posted by nicolai View Post
I am not an expert on raw image data, but
isn't the whitebalance stuff a postprocessing step
after capturing the raw data?
It is, but camera software - also one in our N900 - got some predefined WB "presets" (light bulb, sunny, cloudy etc), that are literally values of "gain" ratio between R,G, and B. I'm also not specialist in such things, but somehow, this values can be exported with RAW - maybe as EXIF data, or whatsnot?

Before someone start to mock me - I know that these things are implemented in software (like UFRaw) as profiles, but *somehow8 people contributing values for so many models are able to get them from camera itself, right? At least, that is how I understand from:
http://ufraw.sourceforge.net/Contribute.html
Still, I don't have a clue, how to get it from N900-created RAw's (I got "no camera white balance data available"), and more complicated things, like getting rid of vignette, isn't covered on this instruction at all.

When camera-ui take RAW image, it also automatically save post-rendered .jpg (nice feature, by the way). Is there any way to "check" white balance (temperature), and other adjustment values used there? It would be very useful, for post-processing using - for example - UFRAW, on desktop computer or N900 itself via Easy Debian.

Now, we can apply manual white-balance, etc, nut no matter how hard I try, overall quality of my resulted image (from RAW processing) is much worse than automatically created .jpg. It's mainly result of white balance *and* vignette. Thinking about that, the latter effect is IMO much more PITA to properly correct, than white balance. I tried every single setting about "vignetting" in ufraw, to no avail. Probably, I'm just noob

Anyway, getting values used by N900 software to create jpg's would be awesome - cause, in other aspects, RAW's give much more opportunities, to create high-quality images. It's just those two twings (white balance and vignette) that ruin final image. ho ever, I remember some discussion - probably, even on this very thread - about nokian's .jpg correction algorithms being closed source - that would be sad news, making RAW capture only a curiosity, without possibility to get really great images (and our N900 camera *is* able to take them, seriously!). Unless, someone reverse-engineer optimal correction values for our camera optics, and publish them.

/Estel

// Edit

The ideal situations, would be to have proper correction values for our optic characteristics (vignette etc), + basic white balance presets, then, sending them to UFRAw (or other Open Source RAW processing tool), to have it included automatically.

This way, when we import our RAW, we got "standard" must-have correction applied automatically, then, we can manually adjust whatever we want, to suit our needs. That would result in super-quality images, that no one expect from N900.

This is, how it works for plentora of digital cameras - even ones from manufacturers, that aren't very friendly to Open Source idea (when it comes to RAW and post-processing documenting), to say at least. does anyone know how people get correction values from such cameras? I don't believe every single one is properly reverse-engineered. - really.

Without such methods - knowing our "Nokia friends" and they openness - superb quality images from N900 are in real of dreams And that's quite annoying, cause we actually got hardware capable of doing so (at least, kicking a** in comparison to *any* other "phone" camera-, even over-advertised N8/N9 one)
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Last edited by Estel; 2011-12-01 at 18:00.
 

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