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

Discussion in 'Digital Cameras' started by self, Nov 28, 2007.

  1. self

    self Guest

    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?
     
    self, Nov 28, 2007
    #1
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  2. self

    ZenDiver Guest

    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
     
    ZenDiver, Nov 28, 2007
    #2
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  3. 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
     
    Toobi-Won Kenobi, Nov 28, 2007
    #3
  4. self

    ZenDiver Guest

    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
     
    ZenDiver, Nov 29, 2007
    #4
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