T3D Re: Digital resolution

[John Ohrt <johrt@xxxxxxx>]

Gabriel Jacob wrote:

> As for the z factor, relatively we can distinguish quite a few levels but
> absolutely I think it's much lower. Don't know what the numbers are but
> nonetheless point well taken. :-)

The eye can distinguish about 700 levels of gray from a photo with
excellent dynamic range.  Since the levels are nonlinear, a much higher
linear resolution is required.  However, empirically, 256 linear levels
is an acceptable compromise for many purposes.  Aslo the use of only
three guns on a crt compromises the fidelity of colour reproduction as
well.

Please note that 256 levels is the display spec, much higher resolution
on input data is required to achieve 256 monotonic linear levels after
processing, hence the popularity of 12 bit output with scientists and
techies.

Another source of error is lossy image compression.  It seems some
cameras don't offer anything but lossy compression.  While I haven't
experimented, lossy image compression results in grain-like phenomena
and from what I hear from the rest of you, that is a very undesirable
"feature" in 3d work.

Regards,
--
John Ohrt,
Toronto * Ontario * Canada



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