[pure-silver] Re: Ruminations On Subject Brightness Range In The Real World
- From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 11 Sep 2012 21:35:57 -0400
Laurence Cuffe wrote:
>
>
> Sent from an iPad,
>
> On 11 Sep 2012, at 23:19, Dana Myers <dana.myers@xxxxxxxxx
> <mailto:dana.myers@xxxxxxxxx>> wrote:
>
>> On 9/11/2012 3:07 PM, Laurence Cuffe wrote:
>>> As just a grey scale the number is surprisingly small, circa 450
>>> different levels. For further reading on this i would recommend
>>> looking up the DICOM grey scale standard,
>>> http://medical.nema.org/Dicom/2011/11_14pu.pdf
>>> And the research reported therein.
>>> this scale does seem limited by the concept of simultaneously able to
>>> distinguish, that is, if we take the full range of light conditions
>>> from extreme tropical sunlight to a fully dark adapted eye, then the
>>> eye can operate over a larger range of light levels than those
>>> defined by the scale, however the scale does seem to give a fair
>>> representation of the ability of the eye to distinguish light levels
>>> in one image.
>>>
>>>
>> [...]
>>> For colour work, it would seem logical to assume that the maximum
>>> number of distinguishable colours would be around (450)^3
>>
>> Is that really true? I'm not sure I see the logical jump from
>> N-shades of grey to M-colors.
>> But I don't know otherwise, admittedly.
>>
> The assumption here is that our ability to distinguish the red component
> of an image is unlikely to be enhanced by the amount of green or blue
> light also present. from this assumption we deduce that if we can
> distinguish between 450 different levels of each of the primary colours,
> then we can distinguish at most 450x450x450 colours in total.
>
> However colour vision is a curious thing, as Dr Land's red blue
> experiments have shown
> http://neuronresearch.net/vision/files/retinex.htm so I would not have
> absolute faith in my conclusions. it is not my field of expertise.
> also I'm fascinated by Jean's mention of an increased ability to
> distinguish colour in a moving image. This makes sense, as we mostly
> sense difference rather than absolute value. I was unaware of that work
> prior to this discusion.
>
> All the best
> Laurence Cuffe
>
>> Cheers,
>> Dana
>>
>>
If you stuff this:
Bell Ttelephone Laboratories J.O. Limb C.B.Rubinstein
into Google, you will find a lot of the work we did at Bell Labs in the
early 1970s. I am even guilty of contributing to some of these efforts.
--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key:3EDBB65E 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 21:30:01 up 18 days, 10:33, 3 users, load average: 4.66, 4.59, 4.42
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