Martin Kramer wrote:
> On Wed, 28 Nov 2007 01:34:57 +0000, ZenDiver <spicedhamme@[EMAIL PROTECTED]
>
wrote:
>
>> self wrote:
>>> How do I duplicate an underwater photo of a color wheel?
>>>
>>>
>>> I want to try to correct underwater photos that I took to reflect the
>>> fact that some colors do not show correctly at depth. I took a color
>>> wheel to a depth of 50 feet and photographed it using natural light. [
I
>>> did not use a flash.] I then took the resulting photo of the color
wheel
>>> and tried to use Photoshop to alter the color so that it would match
the
>>> original.
>>> I can't seem to get the photo of the red sector to look even remotely
>>> like the red original. I do not know much about Photoshop, is my
>>> approach wrong or did I overestimate the ability of Photoshop to
restore
>>> the original colors?
>>>
>> The problem is that there is an uneven loss of the colour spectrum with
>> the red end fading first and so on until everything is in shades of
>> blue. What you need to do is rebuild the red channel in the photo,
this
>> can be a long and complex process. Here is a link to a tutorial from
>> the Digital Diver Network (http://www.digitaldiver.net)
>> http://www.digitaldiver.net/lib_docs/color_cast.pdf
>>
>> Depending on which camera you are using there may be other ways for you
>> to improve the colour rendition of your photos. If you can set the
>> white-balance manually or are able to shoot RAW then you are in luck,
>> otherwise filters are your best bet with ambient light.
>>
>> jon
>
> Interesting. I hadn't considered that the lost reds could be added back
in, not
> having done much underwater photography in the past and nothing more
than max
> snorkeling depths (25-30 ft.). The deeper you go the less time to frame
a shot!
> But then with all the color channels available for tweaking I see how it
could
> be done. Not perfectly but at least salvageable. Not too different than
how to
> make moonlit photos look like more like they were originally taken in
moonlight.
> When properly exposed they look little different than taken in daytime,
totally
> losing the effect you had intended to capture. My fix, desatureate reds,
reduce
> brightness, increase contrast.
>
> While you can't perfectly recreate what was lost to the water, the
spectrum
> section missing or greatly subdued, I see now that you can at least
emulate it
> somewhat. Now I know how to make those shallow depth reef photos look
like I was
> down at 200' while snorkeling. Reverse the process. :)
>
Another possibility to try is known as the "Mandrake" technique, not
sure why. Here is a link that describes it pretty well
http://kayakdiver.com/divephotos/adjustments.htm
jon
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