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For quite some time we were suggesting that floating point implementation of demosaicking algorithms allows for higher quality results. Incidentally, some programmers who vigorously argued for years insisting integer processing is quite sufficient are now starting to code their demosaicking in floating point too. Here is a comparison of the results of original AHD demosaicking algorithm implemented using floating point and integer arithmetics.

Sharp target
AHD interpolation, floating point processingAHD interpolation, floating point processing AHD interpolation, integer processingAHD interpolation, integer processing
Blurred target
AHD, floating pointAHD, floating point AHD, integer processingAHD, integer processing

As you can see demosaicking artifacts are reduced using floating point approach; while resolution is improved.

Integer-processing results are from Bayer Moire article.

It looks like the time spent in postprocessing to get more details and counter-act artifacts might be better spent if demosaicking prepares a cleaner and more detailed image to start with. The processing time difference between integer and floating point implementations of demosaicking most of the times is less than 5 seconds, which is substantially less compared to the time spent on image editing to get close to the same result. Try it, and you will see.

Illiah Borg

Comments

Where is the floating point implementation?

Elle Stone

Iliah, You say "It looks like the time spent in postprocessing to get more details and counter-act artifacts might be better spent if demosaicking prepares a cleaner and more detailed image to start with. The processing time difference between integer and floating point implementations of demosaicking most of the times is less than 5 seconds, which is substantially less compared to the time spent on image editing to get close to the same result. Try it, and you will see. "

How does one go about "trying it" to see? What about this comment:
"For float data output we need to change entire processing pipeline to floating point." from http://www.libraw.org/about?

Elle Stone

Well, those comments are for raw converter developers.

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