First, I open the image in Photoshop in order to address the color. Start by duplicating the image to a new layer so it’s easy to toggle the repaired layer on and off to check your progress and ultimately to more effectively blend the repaired image with the original if necessary.
I start my color repair with the simplest approach: using the Auto Color option under the Image menu. In my experience, this technique almost always makes a notable improvement, and frequently it’s all but perfect. With the example here, the Auto Color adjustment worked terrifically. For further fine-tuning or if Auto Color simply isn’t cutting it, I suggest using a Hue/Saturation adjustment layer. This allows you to tweak individual colors, dialing down green for instance, or increasing the saturation in whatever colors need it.
The final step for almost any color adjustment is dialing in the black point. This can be done easily with a Levels adjustment layer.
Click the top eyedropper in the adjustment layer window to activate the Black Point selection tool. Then, click on an area in the image that should be pure black, and watch as the adjustment layer automatically bases the black point on that selection. The middle eyedropper is for setting a gray point, which isn’t as crucial in my experience, but the third eyedropper is. It’s the white point eyedropper. Click this, then click on an area in the scene that should be pure white, and Photoshop will make it so.
Your image will likely have a much more pleasing contrast and saturation at this point, which can be further tweaked by grabbing the black point slider at the left of the histogram in the Levels adjustment layer panel. Here, you can dial the black level down even further or grab the slider at the right end of the histogram to bring down the highlights. You can watch the histogram for clues, too. If either end of the histogram shows a gap between the nearest peak and the edge of the frame, your black and white points are likely off. To repair this, click and drag to manually set new black and white points at the edges of those peaks.