Clearing a Colour Cast

This is a tutorial for one of the Photoshop techniques I use the most. It’s a great help in quick photo clean-ups.

So, let’s say you have a photo and the colours just aren’t quite right. Maybe there’s a bit of a haze, or there’s a slight colourcast over the image. Try this 30 second adjustment and see what happens.

As an example I will use a photo I took while flying over the Alps this summer. In my experience photos from the air, or across long distances, never look quite as striking and clear as the view when we took them. The moisture in the atmosphere clouds things a little. Before learning this little trick, I used to spend ages with masks, levels and selective colouring, trying to get my airplane photos looking like they should.

Try this:

Step One: Open a photo that needs some work (feel free to save my “before” image from the bottom of this tutorial and practice on that). Hazy and brown, not so nice. This is my CS4 workspace.

Step Two: Create a curves adjustment layer by clicking on the adjustment layer button at the bottom of the layers palette.

(Note: If you’re using CS2 or earlier, your curves palette won’t have the histogram that it does in CS3 or CS4. To do this tutorial and get the same result, open a Levels Layer here instead.)

Step Three: Your curves adjustment panel will open. Here in CS4 it appears above the layers palette, in previous versions of Photoshop will open in a separate dialog box.

In the curves palette, we want the colour channel drop-down menu. RGB will be displayed as default. This means any changes will affect all three of the colour channels in one go. We want to split them up and adjust them one at a time, so click on RGB, and when the menu opens, select the red channel.

(CS2 or earlier: In your Levels Layer, select the colour channel as below)

Step Four: This is where we start making some changes. At either end of the line that stretches diagonally across the curves histogram are two little nodules. Click and drag each one in turn, until they sit directly at the start and finish of the histogram.

Your image will most likely go a strange reddish tint, don’t worry, we’re not done yet.

(CS2 or earlier: from here on in you can follow along exactly the same, just move the black and white arrows under the histogram, instead of the line on curves.)

Step Five: Select the green channel in the same way as you selected the red channel.

Step Six: Again, in the same way as the red, drag ends of the curve line in towards the beginning and end of the histogram. The colour will change again, probably to a murky green.

Step Seven: Back to the channels menu one last time, this time select the blue channel. This is where the magic happens.

Step Eight: Once more, drag the ends of the curves line towards the histogram. This time as you drag the ends in, you should see the colours suddenly become crisp and clear. Feel free to tweak all three channels until you’re completely satisfied with the tones of your image.

Compare the before and after:

Before - Colourcast Tutorial

Before

After - Colourcast Tutorial

After

In this example the photo was very obviously in need of some help, but the technique will make a difference on almost any photo, even if the channels are only tweaked very slightly.

One little note on this… when working on a photo that’s already very bright, look out for the highlights, sometimes they become a little blown out. If this happens, staying a little further from the histogram edges when pulling the lines in should help avoid it.

While you’re playing with the levels and curves, watch how one colour appears as another fades. Understanding the way the colours are balanced within an image is key to being able to create any colour effect you want.

Experiment and enjoy!

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3 thoughts on “Clearing a Colour Cast

  1. Cool! I’m definitely going to try this out on my murky Bahrain airport shots later.

    Love the before and after you used as an example, those edited colours are gorgeous, and the clouds especially look so much better!

  2. Pingback: Using Adjustment Layer Masks «

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