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10-15-2011, 04:05 PM   #1
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RioRico's Avatar

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Digital vs Optical Filters

It's a truism: Most optical filters are unnecessary on digital cameras because the same filter effects can be applied digitally. But can they, really?

Digicams with Bayer filters produce data streams in Red, Green, and Blue channels. The in-camera B&W filters on my K20D are Green, Yellow, Orange, Red, Blue, Cyan, Magenta, and fake Infrared, and these are replicated in the PentaxPhotoLab3 RAW developer. How do these work? PaintShopPro9 and other image editors I've used allow mixing of the RGB channels. Is this how filtration is achieved?

Optical filters may be bandpass, or high- or low-pass. Actually, they're all bandpass AFAIK, just that some band edges may be well outside the visible spectrum. For any standard optical filter, I can find a graph showing its F and Q, the characteristic curve of frequency and bandwidth. I haven't seen any such for digital filters.

So, my question: Does anyone here know where to find the spectral curves for the digital filters used in our warez?

10-15-2011, 04:16 PM   #2
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
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Could you create a test image with an evenly distributed histogram, then simply apply the filters to it and see what happens?

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