[filmscanners] RE: 8bits vs. 16bits/channel: cantheeyeseethedifference

["Paul D. DeRocco" <pderocco@ix.netcom.com>]

> From: Austin Franklin
>
> Can you give a concrete example of what you believe it does?  Do
> you believe
> it takes 0x1289 and converts it to 0x13?  Let's say the entire image is
> completely 0x1280...are you believing that ~half the 8 bit data
> is 0x13 and
> ~half 0x12?  Yes, if you believe that, and can demonstrate it, I'd like to
> see it, and I would agree that is dithering.  But really, no
> entire field in
> real life would consist of 0x1280...there would be a range, and
> in reality,
> simply converting by lopping off the 8 LSBs will give you the same
> "fidelity", from an analysis standpoint.

Photoshop doesn't do this. It optionally adds dither noise when creating an
artificial gradient, but a simple experiment proved to my own satisfaction
that merely converting from 16bpc to 8bpc does nothing more than truncating
each 16-bit value.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

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