A Guest post by Phil Steele from SteeleTraining.com
The Curves Eyedropper technique provides a fast way to simultaneously correct color and fix exposure problems in your photo all at once. That’s a lot of benefit for just a few clicks.
Here’s how it works.
1. Open a photo that you think needs correcting. Our example photo suffers from a blue-green color cast, and it is also a bit “washed out” i.e., lacking contrast.
2. Create a Curves Adjustment Layer by clicking on the Adjustment Layer icon in the Layers Palette, and then choosing Curves from the drop-down menu.
3. Near the bottom of the Curves Dialog, you will see a row of three eyedroppers. From left to right they are used to set the Black Point, the Gray Point, and the White Point.
4. Ideally you should set specific color values for each of these droppers (although you can skip this step and try it with the default values if you like). Double-click on the Black dropper to open its settings, and in the R,G,B values enter 20, 20, 20. For the Gray dropper: 128, 128, 128. For the white dropper: 240, 240, 240.
Now we will simply click once in the image with each of the three droppers to correct color and contrast all at once!
5. Click on the black dropper to select it. Your cursor now looks like the dropper. Click the dropper once in the darkest part of your image. You are telling Photoshop “This spot should be black.” In our example image, this is the hair beside the model’s head.
6. Now click on the White Point dropper to select it. Click with the White dropper in the lightest part of your image. You are telling Photoshop, “This spot should be white.”
7. Now comes the tricky part. You need to use the Gray dropper to select a spot in your image that should be Neutral Gray. This does NOT mean a gray that is exactly halfway between white and black. That doesn’t matter. What matters is that the gray be neutral in color (i.e., its RGB values should be equal). It could be a very dark gray, or a very light gray, so long as it is neutral. Perhaps it does not not look neutral in your photo due to a color cast, but you know it should be neutral in reality.
This can be challenging, unless you have an object in your photo that you know should be gray. For example, in our photo, there is concrete near the model that I know is gray in reality.
Click and I’m done. The shadow on a white object can also make a good neutral gray. But what if you don’t have a gray object or a white object in your photo?
There are various tricks for trying to find neutral gray numerically (such as using the Info Palette and looking for pixels with near-equal RGB values) but these suffer from the flaw that a neutral gray in your image may be already skewed by a color cast. Picking such a point will simply introduce a different color cast.
In the end, sometimes the best you can do is pick points by trial and error that seem like good candidates for Neutral Gray, and just see what happens to the image. If it gets worse, Undo it. When you hit one that satisfies you, you are done.
TIP: There is one trick for finding Neutral Gray in portraits that comes in handy when you don’t have any gray objects in the surroundings. You can sometimes pick on the whites of the eyes to find your Neutral Gray point. This doesn’t always work (some people’s eyes are whiter than others), but when it does, it can be a life-saver!
In our example photo, one click on the white of the model’s eye perfectly corrects the color in the entire image! Her skin is warmed up and the blue-green color cast is gone.
After you correct the color, you may want to tug up on the RGB line in the Curves graph to brighten the overall image.
Compare the before and after photos, and it’s remarkable what Photoshop can do with three little clicks!
You can watch a video version of this tutorial at www.SteeleTraining.com.
About the Author: Phil Steele is the founder of SteeleTraining.com where you’ll find free tutorials on photography, Photoshop, Lightroom and more. This article is based on an excerpt from his video training course
“Photoshop Basics for Photographers”.