In praise of AA filters

Started 6 months ago | Discussions thread
rovingtim
Veteran MemberPosts: 7,928
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Re: Pro AA filter users forget Sigma's Foveon sensor
In reply to Lee Jay, 6 months ago

Lee Jay wrote:

rovingtim wrote:

Lee Jay wrote:

rovingtim wrote:

Whether it 'looks' right or not does not change the fact that this 'detail' is software invented and not optically captured.

Aliasing isn't software-invented, it's spacial frequencies mirrored about the Nyquist frequency.

The software 'fix' to this is to invent 'detail'. How else do we get the appearance of complete detail beyond Nyquist?

Just like I said. There is no detail beyond Nyquist. The detail is below Nyquist reflected from above Nyquist. So, if the Nyquist frequency is 0.5, any information at 0.6 shows up in the final at 0.4. Now, since there is probably real detail from 0 to 0.5, the 0.6 detail now at 0.4 is mixed in with the real detail creating "false detail".

I would suggest manufacturers are attempting to 'complete' the information obtained at 0.6 (etc) using software solutions. That is why the fine detail looks real at a casual glance even though it isn't ... as demonstrated in Basalite's image.

http://www.dpreview.com/forums/post/52397323

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