Eliminating Blue Tint

Discussion in 'Digital Darkroom' started by brian_ellis|16, Dec 23, 2006.

  1. I've recently started using a digital camera and also making color prints
    after years of b&w only so color problems are new to me. I'm shooting in RAW
    mode and editing in CS2. Many of my photographs are made at fairly high
    altitudes under blue or overcast skies. I sometimes get an extreme blue tint
    in the photographs, sometimes so deep that I'm unable to correct it by any
    means known to me. I understand why at altitude and under blue or overcast
    skies I get some blue tint but the degree of it is sometimes surprising. In
    fact calling it a "tint" is misleading, sometimes it's so extreme that for
    example a mountain that's shades of brown and black in real life comes out a
    solid royal blue.

    My question is whether there's a simple way of getting rid of it in CS2
    without also changing the color balance of everything else in the scene. I've
    tried using the color balance eye drop in camera raw, using the color balance
    slider in CS2, making a curves adjustment layer on the blue channel only, and
    a few other things. But so far the only method I've found that really works is
    to select the worst of the blue tinted areas and adjust the color balance.
    That confines the adjustment to the areas I want to adjust (i.e. the severely
    blue areas) without changing everything else in the scene but it's very
    tedious and time-consuming. And even when I don't mind changing the color
    balance of the entire scene when necessary to get rid of the blue, sometimes
    the blue is so strong that even that doesn't work (e.g. using the color
    balance eye drop in camera raw reduces the blue but doesn't eliminate it).

    Any thoughts or suggestions for an easier way to deal with this problem would
    be appreciated (I haven't mentioned anything about dealing with it in-camera
    because I gather this forum isn't for discussion of digital camera stuff).
     
  2. ...please post a sample image...sounds like a problem for LAB
     
  3. Hi Brian, There are a bunch of ways to skin the cat. I'd probably first try (for me anyway) the "easy" way: 1) Duplicate the layer 2) Add a Hue/Saturation Adjustment layer. 3)In the drop-down box with the little arrow, select blue - you can then fine-tune this by just clicking on the blue in the image (say, the sky) to select that color 4) Slide the saturation slider back a bit 'til it looks less pronounced. 5)Adjust opacity of this Hue/Saturation layer to taste.

    Since this will affect the entire layer beneath it and not just the sky, (which may or may not be good), Adjustment Layers come automatically with masks. If you're not familiar, look at the adjustment layer in the layer palette and you'll see a rectangular, white box. Click in it. Now select the paint-brush tool and make sure black is your foreground color. Then paint over wherever in your image you do not want affected by the blue desaturation. (Say, everything but the sky... and you paint on the image itself; not in the little white box) You can adjust the opacity of the brush to be more and less subtle in different parts of the image. If you mess up, simply paint white back in and it'll undo the mess-up.

    You could (don't have to) also *invert* the adjustment layer's mask by clicking in the box and pressing CTRL-I; this makes the blue desaturation go away completely and turns the white box black. You would then use the brush with *white* as your foreground color in exactly where you want the blue de-saturation to appear - as opposed to disappear in the example above.

    Another completely different way: Use Image>Adjustments>Selective Color and get Photoshop to select just the blue sky - assuming that's all you want to target. (Hit help button if necessary but it's not hard to figure out) You could then exchange the "real" blue for a less vivid alternative. If you do this on a separate layer you can then dial the effect in and out with the layer's opacity slider.

    You probably could deal with it in-camera with a custom white balance and/or shooting an 18 percent Kodak gray card in the same light you're shooting in to use as a reference point in PS.

    Also the color temperature slider in Camera RAW just might nail it. Not to mention you can desaturate the blue in ACR too - but it'll effect the entire image which may or may not be cool. The Adjustment Layer mask technique above lets you target just parts of the image. Good luck!
     
  4. Obviously, it would be far preferable to not get this abberation showing up in the photos
    in the first place. Try to prevent it from occurring. Next time you are in similar
    circumstances see how far you get with a good UV filter on your camera. Or experiment
    with warm filters 81B or 85B. Do side by side comparisons on-screen with the same shot
    'au naturel' and with a filter. See the difference.
     
  5. Here's a technique that I picked up in a recent issue of Photoshop User magazine. Duplicate
    the image and apply Filter>Blur>Average. Use this image with the Set Gray Point eyedropper
    in either Curves or Levels to neutralize color casts.
     
  6. Have you tried adjusting the Blue curve?
     
  7. Oops, sorry, you have...I missed that. My apologies!
     
  8. Sorry if it is obvious but... instead of using the eye drop in Camera RAW, have you actually moved the Temperature slide around?

    Also, if the blue is in the shadows, you can try adding a Color Balance layer, select Shadows and then lower the Blue slide (somebody pointed this out to me some time ago on this forum).
     
  9. You need to adjust your white balance settings to match the color temperature of the available light. try this tutorial: http://www.cambridgeincolour.com/tutorials/white-balance.htm
     

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