Thom Hogan's review of the A7/A7r

Started Mar 10, 2014 | Discussions thread
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Erik Magnuson Forum Pro • Posts: 12,247
Re: Thom Hogan's review of the A7/A7r
1

LTZ470 wrote:

Yes, I have seen posterization, but I have seen it in ALL the other cameras I have used to some varying degree...who cares, it's not common and only happens in the sky of shots certain times...and he is correct it takes "someone" looking for it to find it...

The Sony posterization has a unique signature based on the 32-pixel blocks for delta encoding: these compression artifacts will occur near high contrast edges. Worse case is a bright diagonal line where it is not visually lossless.  In theory, any horizontal line that covers more than 128 levels has artifacts.  In real photos after demosaicking, denoising, and sharpening, most of these are smoothed into such minor hue/brightness errors that you cannot see them.  In that sense, it's like the difference between a high quality JPEG and a TIFF:  you can spot "errors" by doing a difference but most of them are too small to be visually noticable - our eyes are just not good at detecting subtle color edges.

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Erik

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