Using a Gray Card

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I have been using a digital camera since 2002, and have since owned two different cameras. My first camera was a Canon G2, while my current camera is a Canon S3 IS. I enjoyed using the G2, and am currently enjoying the S3. One of the biggest differences between the two cameras was the picture file format. With the G2, I used to store the pictures in a RAW format, while with the S3 I can only store the pictures as JPEG.

For most people, the JPEG format is the one they will use. I enjoyed use the RAW format since I’m not a great photographer so I like the ability to change my settings after the fact. For more information on the two formats, please read my JPEG or RAW Format post. With the JPEG, I now need to get my settings correct within the camera, and this includes the colour settings.

To ensure that I get the colours in my pictures as close to accurate as I can, I use a gray card. Using a gray card is really simple to use, and can be used with any digital camera that allows for a custom white balance to be set. Gray cards can be purchased at any camera store. I use WhiBal since it is smaller, durable, and contains both a white and black patch as well.

Setting White Balance for JPEG

My workflow for use a gray card is as follows:

  1. I place my gray card in a place that is lit by same light as my picture. If I’m outdoors on a sunny day I place my card in the sun. When indoors with a light source, I place it under the light. Doing this will make sure the light provides a colour cast to the gray card.
  2. Next, I set my camera to custom white balance. The manual that came with your camera will explain how to do this.
  3. I then fill my viewfinder, or LCD screen, with the gray card so it is all that I can see.
  4. I press the button on my camera to set the white balance off the gray card.

As long as the lighting doesn’t change, I can now use the same white balance settings for all my pictures. If the lighting does change, then I just repeat the above steps to set a new white balance.

Setting White Balance for RAW

Setting the white balance for a RAW format picture is much easier, when taking a picture, than a JPEG. You can follow the same steps as a JPEG, but with a RAW file you can set the white balance after the picture is taken. The following steps outline the workflow for a RAW file:

  1. I place my gray card in a place that is lit by same light as my picture. If I’m outdoors on a sunny day I place my card in the sun. When indoors with a light source, I place it under the light. Doing this will make sure the light provides a colour cast to the gray card.
  2. Instead of setting the white balance manually, I set the camera to "Auto" or "Program".
  3. I then take a picture of the gray card (it doesn’t have to fill the viewfinder, just as long as it is in the picture).
  4. I keep the same settings, and take my pictures.

Just as with a JPEG you will need to repeat the above RAW format steps when the lighting changes.

As mentioned earlier, the white balance for RAW pictures can be set after the fact in a photo editor. The following steps outline how to correct the white balance:

  1. Once all the pictures (including those with the gray card) have been downloaded to your computer, open the gray card picture in a photo editor.
  2. The editor will usually provide a means to set the gray level in the picture. For example, in Photoshop it looks like a gray eyedropper. Select that, and then click the gray card in the picture.
  3. Save the colour settings to your computer.
  4. Apply the saved colour settings to all pictures that were taken in the same lighting conditions.
  5. Repeat for all gray card pictures that were taken.

Summary

This post provided a quick overview of how to use a gray card when saving a picture in either JPEG or RAW format.

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