Yes, of course, we know there are scores of plugins and built-in features for newer Photoshop versions that correct the shifted white balance in seconds. This tip is not aimed at those who lack free time but masochists. Or, in a nicer way, at people who like to experiment, tread new roads, even if those roads are long and winding. We haven’t used the Curves feature for more difficult tasks yet. So now it’s time!
Open the photo in Photoshop
Somebody has messed up something on a grand scale with white balance here.
First, you should assess in which direction the picture diverges from the colors perceived by the human eye. This time it’s a fairly fast job as the originally white background spurts an unwanted and easily spottable blue-cyan color.
To treat this, you have to adjust the curves for the red and green color channels while leaving the blue channel untouched. For a greenish tint, adjust the blue and red channels, and for a reddish one, blue and green.
Green color channel
Click Image/Adjustments/Curves. At the top of the dialog, choose Green from the Channel dropdown.
Click the upper right handle of the curve and drag it upwards.
Red color channel
Do the same after selecting the Red channel. Be sure to select the Preview check box so that you can keep an eye on the effect of the changes you are making. If the result needs refining, change back to the green channel and adjust it as needed. You can also type in numeric values in the Input field, e.g. in steps of -1. Adjust finely the red color channel’s Input value as well to restore the color levels you want.
Just like two eggs
The colors of the resulting image look much more realistic.