Sony a77 appears to fake video specs!

Started Feb 26, 2013 | Discussions thread
TrojMacReady
Senior MemberPosts: 8,447
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Re: Still not line skipping
In reply to Alphoid, Mar 3, 2013

Alphoid wrote:

TrojMacReady wrote:

Semantics or not, the point stands that sampling by ignoring surrounding pixels when replacing them, is far more detremantal to the quality of output including resolution. Aliasing and moire (false detail as such) shouldn't be confused with real resolution to begin with.

This is completely false and incorrect. Subsampling maintains all of the resolution possible in the original image up to the Nyquist frequency of the new image. It maintain as much detail as is possible to maintain at the new resolution. Algorithms can do worse for resolution than subsampling, but they cannot do better.

It's not false at all. What's false is counting false detail as real resolution and claiming that you can't reduce moire after the fact.

The very samples you posted using subsampling and line skipping, highlight my point. Lines changing angles, breaking up and almost merging (see barcode lines above "ZA") is not real detail, that's false detail. Throw a dumb 0.3 radius Gauss filter over your subsampled version and you get a result without aliasing and much closer to the out of camera 1080P version, minus compression and codec artifacts of course. Obviously with an extra loss of detail too. Which is mostly likely similar to what's happening in camera as well to mask aliasing et al.

And of course never as effective as removal/prevention in hardware (reading out the full sensor with better sampling or native full HD sensor resolution, effective OLPF).

Your version using line skipping with strong aliasing (especially visible in the bottom barcode) present:

Gauss filtererd with 0.3 radius to remove aliasing:

Out of camera version:

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