Project 39: Color Correction

From today's warm up you might find it hard to believe that color can cause photographers a lot of trouble. Let's look at an image:

This is a picture from Ms. Field's cooking class. The subject looks normal, but what can you see is wrong with the photo?

If you guessed it looks a little yellow, you would be correct. The walls of our classrooms are not yellow. So, what is going on in this photo? The COLOR BALANCE or WHITE BALANCE is not correct.

To understand what this is, you need to understand COLOR TEMPERATURE.

"White" light can actually be a variety of colors. When a camera takes a picture it changes the photo a little to make white light look white. If the settings are wrong you'll get a picture with a COLOR CAST that isn't correct. We can correct that by setting the camera to AWB or selecting the white balance ourselves. Sometimes, however, the setting is wrong and we get a picture like the one above; too greenish-yellow.

To fix this we can use the power of Photoshop. Actually, there are quite a few ways to fix this, but we will use the one that works pretty well in most situations.

1. Open your photo to be color corrected. We'll us the one from he beginning of this post. 
2. Create a new layer. Press SHIFT and BACKSPACE on the keyboard. A window should come up.

From the pull-down menu select 50% gray.

4. Change the blending mode of the layer to DIFFERENCE. The picture should look pretty crazy. 

Like this:

3. In the LAYERS palette, press the black and white cookie to make a new CURVES ADJUSTMENT LAYER. Select the gray eyedropper in the palette:

4. In the photo you are going to pick the blackest part of the image. In the sample above, I selected the plastic bag of the garbage can. In reality this is a light color, but we are trying to see where 50% gray is in the photo.

5. Click on the spot and the picture will change a little. Hide the gray layer and you should have a picture that has more normal colors. The example below has a mask to show the difference.

That's the step. It's pretty easy and fairly automated. 

Your assignment is to either find three photos you have taken and color correct them OR take three photos with the incorrect color balance selected and then correct them.