Color Correction

This tutorial will show how to correct for a color cast in an image by using the set gray point eyedropper located in either the levels or curves dialog box.

To follow along on this lesson you can download the full size image from the zip file located here.

It's all about the gray areas

Open the Lake-Louise.psd image.

Because the image was shot before sunrise there is a severe blue color cast.

If an image with a color cast has an obvious area that should be a neutral gray color it is easy to fix the problem.

Just create a levels (or curves) adjustment layer, and choose the middle eyedropper (set gray point).

Click the eyedropper cursor over the area in the image that should be neutral and the levels adjustment will correct the color cast automatically.

 

Lake Louise

When there's no discernable neutral area

In images that have no obvious neutral area, several steps must be taken prior to the levels adjustment in order to identify the neutral parts of the image.

Here's how:

1) Create a new layer above the image layer by clicking on the new layer icon on the layers palette.

2) Go to the top menu bar and choose Edit / Fill. Select 50% in the contents pull down menu. Click OK. Your image will now look completely gray.

3) With the new layer active (layer 1 in this example) go to the levels palette and change the blending mode pulldown menu from normal to difference. Your image will reappear in altered form.

How difference blend mode works: The areas of the underlying image layer that are closest to the color of the difference layer (50% gray in our example) will appear darkest. Therefore we want to choose the darkest part of the image to locate the most neutral area.

 

 

difference layer

Here's how:

1) At the bottom of the layers palette, click on the fourth icon in, the black/white circle (new adjustment layer). Select threshold from the choices given.

2) In the dialog box move the slider at the bottom of the graph all the way toward the left until just a small amount of your image remains black. These black areas signify the darkest parts of the difference-altered image, hence the most neutral portions of the image.

threshold

3) Go to the toolbar and choose the eyedropper tool. Click and hold until the pop up menu appears. Choose the Color Sampler Tool.

4) Move the color sampler cursor over your image to one of the black areas. Click once to place a temporary bulls eye that will help identify the area later.

5) Now click on the threshold layer in the layers palette and drag it to the trash can at the bottom of the palette to delete it. Do the same with the difference layer.

6) Your original image will remain with a bulls eye located over the most neutral portion of the image.

 

color sample tool

Finally, create a levels adjustment layer by clicking on the adjustment layer icon you previously accessed.

In the levels dialog that appears choose the middle eyedropper. Move the eyedropper over the bulls eye in the main image and click.

Click OK in the levels dialog box.

cc levels

Optional

In this particular image I wanted to leave a slight color cast in the picture to convey the feeling of early morning. To achieve this I lowered the opacity of the levels adjustment layer slightly to bring back a little of the blue.

Lake Louise final
 
© 2007 George Garbeck