For David Millier

Started Feb 4, 2013 | Discussions thread
richard stone Senior Member • Posts: 2,124
Re: I'll get my coat ;-)

Truman Prevatt wrote:

Today a lot of RF signal process is performed with a slow rolloff anti-aliasing filter with linear delay characteristics to reduce distortion or intersymbol interference in digital communications. That is followed by a linear phase sharp cut off digital low pass filter and a decimation in sample rate.

That would be the clear best solution to AA filters in digital cameras since the LiNb filters used have very poor characteristics. However, today that is not feasible. When the sensor MP count gets into the 100's of MP that would be a feasible approach.

Part of the problem is the lack of robust filters in the visible specturm.

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So the answer is that the solution to the claimed "problem" has to take into consideration the limited and imperfect nature of the current technology that may "cure" the problem. (Not that all the people who post on either side of the issue understand the true nature of "problem" entirely or correctly, but they say they know what they like. Or more likely, like what they know.)

Thus, before proceeding much further someone/each of us has to decide whether the "problem" is severe enough to warrant the application of that imperfect (and by definition, always destructive) "cure."

Leica and Fuji and Sigma have taken the approach that the AA filter losses outweigh the gains, and by such an amount as to require them to eliminate the AA filter entirely. Nikon has a special model to deal with the issue.

It seems obvious that handicapping the above non-AA filter cameras with such an (imperfect) filter would level the playing field, and then all the images from all cameras would be nice and smooth, and blurry. The answer seems easy enough, really: if you prefer smooth images, and the Foveon is too sharp or edgy, get a camera that comes with an AA filter and be done. Or put a blurry lens on the new Foveon sensor camera.

I do not intend to dismiss or even minimize the technical aspect of this discussion, but the purpose of the equipment is to produce images that are accurate or pleasing and useful to the user. These are not mutually exclusive goals, in all cases, but sometimes they are. Things that get in the way of those objectives, that is to say, things that get in the way of using the camera as desired, are going to be resisted, and properly so. There are many choices.


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