Wow, pretty amazing. But I don't think I want any UV or infra-red opsins.
Chuck Norcutt
usher99@xxxxxxx wrote:
> Very interesting thread--thanks Tim, AG.
>
> Timely too as was just reviewing a recent article in Nature on curing
> color-blindness in primates---also an editorial a week ago in the NEJM.
> So perhaps we eventually can "upgrade" our own sensors.
>
> http://www.nature.com/nature/journal/v461/n7265/full/nature08401.html
>
>
> Approximately 8% of men have a loss of or defective opsin--usually the
> long or middle wavelength one---thus are "dichromats" like the
> monkeys in the Nature article. They were able to deliver a wild-type
> human L-opsin gene to long and middle-length cones via a
> replication defective adeno-associated virus injected
> sub-retinally---resulting in trichromatic vision in the
> monkeys!!---still appeared to work after 2 years.
> One might have predicted that even if the hardware were fixed, the
> brain would not process the signals well (analogy to congenital
> cataracts must be fixed quickly for normal vision to be established)
> but that was not the case.
>
> Sooo, theoretically if this process is safe and effective one might
> choose an upgraded "sensor" by creation of tetrachhromacy--
> why not add another opsin like in the European starling and see flowers
> the way they are supposed to be seen by starlings and bees?
> Nah--would be instantly dissatisfied with all current gear.
>
> Mike
>
>
> Tim, excellent post !!
>
> During 1977 - 78 I subscribed to Scientific American, I may have had
> that article 'though I lost many of the monthly issues ....emmm, only
> six remain in my library. During those years I made an attempt to go
> to the States to study biochemistry. I didn't win the grant, long
> story.
> I do have some serious works on perception, just yesterday I read one
> here, about tinnitus (I'm very worried about my new audio monitors ...
> :-) )
> <http://www.pnas.org/content/early/2009/12/15/0911268107.full.pdf+html?si
>
> d=7e5a21bd-942e-4e1c-9582-5b924ba5a791>
> This also relates to an old post of Chuck regarding hearing loss.
>
> Cheers,
>
> Fernando
>
> 2009/12/31 Tim Hughes <timhughes@xxxxxxxx>:
>> Ken, a couple of comments:
>>
>> People interested in the human perception issues of color, might
> enjoy
>> reading the long popular article by Edwin Land (Polaroid fame), which
>> appeared in Scientific American.(Edwin H. Land, "The Retinex Theory
> of Color
>> Vision," Scientific American, Vol. 237, No. 6, pp. 108-128, December
> 1977.)
>> His theory of color perception is termed "Retinex theory".
>> here are a few related simplified links:
>> http://people.msoe.edu/~taylor/eisl/land.htm
>> http://www.wendycarlos.com/colorvis/color.html
>> http://en.wikipedia.org/wiki/Color_constancy
>> http://www.wendycarlos.com/colorvis/retinex.html
>> http://color.psych.upenn.edu/brainard/papers/retinex.pdf
>> http://www.rowland.harvard.edu/organization/land/theory.php
>>
>> One interesting thing is the brain can do a surprisingly good job of
>> reconstructing a full set of colors from a display screen, even if
> only 2
>> types of carefully chosen color pixels are used, in place of 3.
>>
>> There are so many variations on the more than tri-color camera sensor
> matrix,
>> which have been suggested and patented. A very interesting variation
> but for
>> color screen display use, is using RGBW. (W = white)
>>
>> Some of the Fuji and other >3 color sensors land up with
> non-rectangular
>> pixel layout. This can mean the resolution is highest on a diagonal
> not
>> horizontal and vertical axis. This is a slight disadvantage
> apparently, as
>> we percieve better sharpness, if the resolution is highest on the
> horizontal.
>> A dificulty with the Foveon sensor, is not just their execution and
> having to
>> have a different dematrixing software/hardware, which is more
> expensive
>> because of lower volumes,but the RGB absorbtion curves have very
> broad
>> overlap with one another, making it much harder,to seperate the
> colors
>> accurately. This tends to magnify the noise despite the inherent
> advantage of
>> not throwing away more than 2/3 of photons, as in the normal 2D
> filter
>> sensor. Using another type of vertical filter in a stackerd sensor,
> as you
>> suggest, could theoretically retain this photon (noise) advantage, if
> it were
>> practical to make.
>>
>> The human eye is similar to the Foveon sensor in that the absorbtion
>> spectrum of the different Rhodpsins in the eye are very similar, with
> huge
>> overlap making the brains job much tougher, in sorting out the real
> colors.
>> This is an example of why the eye is a rather imperfect, but highly
> optimised
>> design, despite what old creationists used to claim about godly
> design
>> perfection in the eye!
>>
>> see curves here: http://www.wendycarlos.com/colorvis/conecurv.jpg
>> and discussion of opsins here :
> http://en.wikipedia.org/wiki/Rhodopsin
>> Tim Hughes
>>
>> --- On Mon, 11/16/09, Ken Norton <ken@xxxxxxxxxxx> wrote:
>>
>>> From: Ken Norton <ken@xxxxxxxxxxx>
>>> Subject: [OM] Pixel Wars - The Next Generation
>>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>>> Date: Monday, November 16, 2009, 5:09 AM
>>> A shameless plug alert.
>>>
>>> We have a new article posted on Zone-10 which is predicting
>>> future
>>> development of sensors in our digital cameras. I'm sure a
>>> few things in it
>>> may seem a little futuristic, but isn't that the purpose of
>>> a prediction
>>> article? However, each and every technology mentioned in
>>> the article is
>>> found through patent searches and some slick detective
>>> work.
>>>
>>>
> http://zone-10.com/cmsm/index.php?option=com_content&task=view&id=461&Itemid=1
>
>
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