Which Raw Format?

Started Oct 6, 2012 | Discussions thread
alanr0
Senior MemberPosts: 1,220
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Re: Which Raw Format?
In reply to GordonBGood, Oct 16, 2012

GordonBGood wrote:

alanr0 wrote:

Where it gets more interesting is when someone (often Fuji) comes up with a different (non-Bayer) sensor layout.  Presumably DNG has a means to describe the layout.  Is there a default (perhaps highly inefficient) demosaic algorithm, or does a new a layout require custom software?

Alan, DNG is capable of describing the new Fuji non-Bayer Colour Filter Array (CFA) pattern just by using the standard metadata tag to describe a six by six CFA pattern rather than the usual two by two one.  However, just because the raw pattern can be described doesn't mean that usual demosiacing algorithms, which are often highly optimized toward two by two dimension patterns, will work.

In this case, one could use a form of linear interpolation and could likely avoid most of the usual "zipper" artefacts that come with linear interpolation by offsetting the pattern for a more symmetrical application.  This would come at a cost as far as deriving the maximum in resolution from the raw image, but probably the cost in resolution due to demosiacing would still be less than the detail resolution gained in not having an Anti Aliasing (AA) filter.  I'm not sure if this is the approach that Adobe Camera Raw (ACR) and Fuji's own raw conversion software uses or not.

Regards, GordonBGood

Thanks for the clarification Gordon. (And for Barry's reply too).

It will be interesting to see if support for Fuji's EXR sensor improves, as the option to increase the dynamic range of a compact camera, compared to a standard 2/3 inch or 1/1/7 inch sensor, is appealing.  Dpreview reported that for the Fujifilm X10 , in-camera conversion produced better results than either ACR, or the version of Silkypix bundled with the camera.  Even if the firmware algorithms are kept under wraps, this gives the 3rd party guys something to aim for.

Cheers

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Alan Robinson

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