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Strange output from DNG files, JPG are normal

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Strange output from DNG files, JPG are normal
« on: 14 / February / 2012, 14:27:07 »
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Hello again.

I'm playing with making photos in RAW and saving as DNG files. I got very strange output - please see attached files. My camera (SX230HS) is saving two files, in JPG and DNG. JPG looks normal but DNG looks vignetted and distorted - vertical lines are clearly curved (I have more examples).

Why I'm seeing such behaviour and what can I do to avoid it?

Re: Strange output from DNG files, JPG are normal
« Reply #1 on: 14 / February / 2012, 14:54:35 »
Why I'm seeing such behaviour and what can I do to avoid it?
What you are seeing is perfectly normal.  RAW & DNG images are exactly what the camera gets from its sensor - warts & all.   So what you see is what the lens in your camera produces.  The camera processes that data, making various corrections for optical distortions internally and then compresses it into a JPG file format. 

So,  you asked for RAW - you got RAW.  Anything beyond that requires image editing software on your PC.
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Strange output from DNG files, JPG are normal
« Reply #2 on: 14 / February / 2012, 16:17:42 »
There should be a wiki page to describe this, since this question appears again and again :)

BTW this can be used for funny effects - you can make a photo with the highest zoom, then change zoom to minimum and then develop RAW you have obtained before. Camera will perform 'correction' as for the present state, not for the state, when RAW was made. This also applies to the other order. The effect is a little simmilar to the fish eye or re-fish eye.
if (2*b || !2*b) {
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Compile error: poor Yorick

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Offline reyalp

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Re: Strange output from DNG files, JPG are normal
« Reply #3 on: 14 / February / 2012, 16:23:03 »
There should be a wiki page to describe this, since this question appears again and again :)
I just added
http://chdk.wikia.com/wiki/FAQ#Q._My_RAW.2FDNG_files_are_distorted.2C_what.27s_wrong.3F

Feel free to add additional details in http://chdk.wikia.com/wiki/Raw
Don't forget what the H stands for.


Re: Strange output from DNG files, JPG are normal
« Reply #4 on: 15 / February / 2012, 14:00:43 »
Hey guys can someone help me with this one. The DNG file that chdk produces in my a3300 is totally purple, the jpeg is normal but the dng isn't. Someone help please.

Re: Strange output from DNG files, JPG are normal
« Reply #5 on: 15 / February / 2012, 14:02:46 »
This is how it looks like guys. Someone help!

Re: Strange output from DNG files, JPG are normal
« Reply #6 on: 15 / February / 2012, 14:57:04 »
I have not followed the A3300 porting thread but that degree of purple cast normally means the wrong colour-filter array has been specified by the porter.

If not, then it is up to YOU to determine the values for the colour matrix, if you are convinced (for some reason) that the result will be worth the effort.

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Offline fe50

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Re: Strange output from DNG files, JPG are normal
« Reply #7 on: 16 / February / 2012, 01:20:06 »
The DNG file that chdk produces in my a3300 is totally purple, the jpeg is normal but the dng isn't.
Since there are no similar results reported on the A3300 porting thread (http://chdk.setepontos.com/index.php?topic=6972.240), this may be an issue with your image processing software.

You may try another RAW editor, e.g. RawTherapee or XNView for testing; try also different RAW settings in your software, e.g. the white balance setting...

* http://chdk.wikia.com/wiki/Software


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Offline Lebeau

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Re: Strange output from DNG files, JPG are normal
« Reply #8 on: 16 / February / 2012, 10:04:04 »
I don't have A3300 but, for DNG file, I always use Photoshop or Lightroom. You could also find a DNG CODEC to display within Windows Explorer at Adobe Labs, just to be sure of the DNG contents.

Re: Strange output from DNG files, JPG are normal
« Reply #9 on: 16 / February / 2012, 13:22:46 »
Why I'm seeing such behaviour and what can I do to avoid it?
What you are seeing is perfectly normal.  RAW & DNG images are exactly what the camera gets from its sensor - warts & all.   So what you see is what the lens in your camera produces.  The camera processes that data, making various corrections for optical distortions internally and then compresses it into a JPG file format. 

So,  you asked for RAW - you got RAW.  Anything beyond that requires image editing software on your PC.

RAW with such distortion? I have another camera - Nikon D40x - and when I'm taking photos in NEF (internal Nikon RAW format) I got same files as in JPG; maybe slightly different colours which I correct in DCRaw but without any barrel distortion.

I'm really confused...

 

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