How do I duplicate an underwater photo of a color wheel?

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self - 28 Nov 2007 01:14 GMT

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?

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Pat

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ZenDiver - 28 Nov 2007 01:34 GMT

> How do I duplicate an underwater photo of a color wheel?
>
[quoted text clipped - 8 lines]
> 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

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Martin Kramer - 28 Nov 2007 14:58 GMT

>> How do I duplicate an underwater photo of a color wheel?
>>
[quoted text clipped - 22 lines]
>
>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. :)

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ZenDiver - 29 Nov 2007 13:04 GMT

>>> How do I duplicate an underwater photo of a color wheel?
>>>
[quoted text clipped - 37 lines]
> 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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Toobi-Won Kenobi - 28 Nov 2007 14:52 GMT

> How do I duplicate an underwater photo of a color wheel?
>
[quoted text clipped - 8 lines]
> approach wrong or did I overestimate the ability of Photoshop to restore
> the original colors?

This is not unlike the colour casts you see in old photos, caused by
chemical reactions to light in the different layers of the emusion.
Some success can be achieved by using the levels command, (ctrl +l)
adjusting each individual channel in turn, not the master.
With the command active and a channel selected, hold down the alt key whilst
dragging the right hand triangle (highlight)to the left.When you hold down
the alt key, the channel window will take on the colour of the selected
channel and when you drag the triangle to the left, you will see a break
through (area of black appear) when the highlights come into range in that
channel. You can also do the same for the shadows (left hand triangle, drag
to the right.).
Whe you have corrected all three channels, check your result in
Image>Adjustments>Variations (highly underated for colour correction) and
tweak accordingly.

TWK

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Sheldon - 30 Nov 2007 02:34 GMT

> How do I duplicate an underwater photo of a color wheel?
>
[quoted text clipped - 8 lines]
> approach wrong or did I overestimate the ability of Photoshop to restore
> the original colors?

As you go down you will lose colors in order of the spectrum (red, orange,
yellow, green, blue, indigo and violet). I asked someone once if I should
get yellow fins so they will be easier to see, and was told that the only
place you will see them is if you are in trouble and waving them over your
head on the surface. As you can see by the spectrum, yellow is one of the
first colors to go, and will just turn gray to the diver's eye.

The only way I know of to correct colors underwater is to use lights or a
flash. If you know what the colors are you can always fill them in using a
program like Photoshop, but it won't look as natural as with a flash or
lights.

Good luck.

Sheldon

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