Removing A Color Cast
From A Photograph

This picture has a nasty color cast, no doubt about it, and the biggest challenge is how to eliminate it.

Jim

The annoying things about this kind of color cast is that it only seems to happen to pictures that one really cares about and it can be really difficult to get back to the original color.

What we are going to do is let Photoshop do the best it can do to restore the picture to something like normal using a Curves Adjustment Layer. If that is not enough then we will add the very best black and white conversion to the adjustment layer and that should do the trick.

It can be a fiddly kind of technique but the results are more than worth it if we can eliminate that nasty color.

Here's How To Do It ...

1. Open the picture with the nasty color cast.

2. Now we will let Photoshop do the best it can do to eliminate the offending color.

   Curves Adjustment Layer

   Selecting Layer > New Adjustment Layer > Curves brings up the Curves Adjustment Layer dialogue.

   Click on Options. This will open the Auto Color Correction Options dialogue box. This is where Photoshop gets its chance to correct the color cast of the picture.
   
   
   
   

3. In the Auto Color Correction Options yo will see a number of different options. You will notice a change in the picture with the default setting, however, try the settings in the graphic.

   Auto Color Correction Options

   
   
   The new settings are:

   Find Dark & Light Colors
   Check Snap Neutral Midtones
   Shadows: Clip: 0.010
   Highlights: Clip: 0.010
   

   Click OK.

   The picture sure looks a whole lot better but there is more to do.

4. Now we are back in the Curves Adjustment Layer and there is one more thing to do here.

   Select the middle eyedropper (Set Gray Point) and scan the image for an area that should be a middle gray tone. Select it with the eyedropper.

   Curves Adjustment Layer

   
   
   Keep doing this until you are satisfied with the result then click OK.

   All things considered, Photoshop did a pretty good job with this image but we can tune it up even more.

5. The next step is to create a new layer to mix the contents of the current layer and an optimized grayscale layer. With the Curves layer active, press:

   Shift - Option - Command - N and then E (MAC)
   Shift - Alt - Ctrl - N and then E (Windows)

   This creates a New Layer and merges a copy of the underlying layers into it.

6. Now we will create a grayscale image using the Channel Mixer. Before rushing ahead and opening the Channel Mixer, take a look at the individual Channels that make up the picture - Windows > Channels if they are not on your desktop.

   Click each channel in order (Red, Green and Blue) to see what they are made of. Generally the Blue channel will be very noisy and the Red and Green channels will be better representations of a grayscale image.

   Channel Mixer

   Before we make the Channel Mixer layer, turn off the Curves and Merged Layers by clicking the eyeball on each one. This will leave only the Background Layer visible. Select it so that it is the active layer. The channel Mixer layer will be directly above the Background layer.

   Click Layers > New Adjustment Layer > Channel Mixer ... and put a checkmark in the Monochrome box. Now you have a grayscale picture.

   What needs to be done now is to move the Red and Green sliders around until you get the best grayscale you can get. If it is still a bit off then move the Constant slider to find the best grayscale you can.

   In the example, the values are:

   Red - +78
   Green - +82
   Blue - 0
   Constant - -28
   

   When you are satisfied click OK.

7. Now we have four layers - Background, Channel Mixer, Curves 1 and Merged Layers.

   Merged Layers

   Check the eyeball beside the Channel Mixer and the Merged Layers to blend them together (but not the Curves Layer).

   Now select the Merged Layer and set its blend mode to Color. This will force Photoshop to combine the color of the top layer with the tonality of the Channel Mixer (grayscale) layer.

That's it! It is done and the 'rescued' image is acceptable. Hopefully you will rescue some prized photographs with a nasty color cast using this technique!

Original	Corrected

Return to Photoshop Tutorials from the Color Cast page.