Re: Zeiss paper

[T3D John Ohrt <johrt@xxxxxxx>]

T3D john bercovitz wrote:

> So the curve marked by asterisks is better than the curve marked
> by exes if the visual acuity limit (for the distance from which
> the photo is being viewed) is marked by the ells.  They
> mentioned that under the best of conditions, a contrast of 5%
> was sufficient for resolution by the human eye.  Sure makes 120
> lines per mm sound pretty weak if it's at 5% contrast, eh?

A note of caution.  5% contrast is a display requirement.  When the
world required that all film processing was by chemistry, 5% was a
valid criterion for the end product.  Today, much smaller contrast
is easily enhanced to the 5% level through digital processing of
images from scanned film or digital cameras.

While this may seem only scitech, I think it could be employed
artistically in areas such as still life of found objects etc.
especially where the lighting conditions and available equipment
preclude the use of optimal contrast resolution.

Any graphics software package incorporates this capability, so
someone must use it, I hope.  <grin>

BTW, a well adjusted 8 bit digital image can resolve a contrast of
0.4%

Regards,

--

John Ohrt * Toronto * ON * Canada





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