This is the follow up post to “Making Your Own Gray Card”.
There are a few methods you can use to obtain your white balance using your gray card:
One method for using the gray card is to include the card in a test/reference image, shot in RAW format. You can then continue shooting under the same lighting conditions as the test/reference image. For each lighting change, a new test/reference image will need to be shot. Your camera should allow you to shoot in AWB (Auto White Balance) mode. It is important that you read your camera and software instructions to make sure this method can be used.
Transfer the images to your computer using whatever method you are familiar with. Once the transfer of images is complete you can open your RAW conversion software. Most RAW conversion software packages allow you to pick a neutral gray color point on an image to set a custom white balance. You can use the gray card as your neutral color point. You will now be able to apply that setting to all the images shot under those lighting conditions. See your camera and RAW conversion software instructions.
Use the same shooting method as if you were shooting RAW (see above) but instead set your camera’s image output to JPEG. After you have transferred your images to your computer you can now color balance them in your favorite image editing software. Use the reference image with the gray card in it. Open up the levels adjustment and click on the middle eye dropper tool to set gray point. Now, just click on the gray card and your image is white balanced. Check your software for specific instructions on applying the settings of the reference image to the rest of the images shot under those lighting conditions.
The gray card can be used to obtain your white balance using your cameras internal white balance utility. Just place the gray card in front of your lens and fill the entire frame with the card and use your cameras internal utility to create a custom white balance. See your camera owner’s manual for instructions.