DIY: Making Your Own Gray Cards
Most cameras are capable of creating 'acceptably good' white balance on your photos. And even if they're failing, you can make a pretty decent guess for what you think the white balance should have been in post production.
But what if you want to take the guesswork out of the equation, and get perfect white balance every time? The professionals use something called a 'gray card' (or 'grey card', depending on where in the world you learned to write English). The name says it all: it's a gray piece of card or plastic that you can use to balance your photographs.
Finding yourself a gray card
Does that sounds a bit high tech? Well, it really isn't - and the great news is that you can use just about anything that is neutrally coloured. Of course, without advanced colour calibration equipment, it's hard to find something that's actually perfectly neutral. For our purposes, however, you don't need to do that: anything that's just about gray will do. Why? Because once you have your photos balanced consistently, it's easy to make sure they are all well-balanced.
The silver on the Macbook Pro is relatively neutral, and can be used as a grey card
You can use anything that is neutrally coloured, but we would recommend using something that's light gray - it gives the camera the best colour reading, and it makes it easier to do your balancing in post production, too. The lids on coffee cups tend to work pretty well, and personally, I've been using my Macbook. The matt, light silver material is relatively neutral, and since I tend to bring my laptop on photo shoots with me, it's always there when I need it.
Printing off a gray card
If you know what printer you are going to be using to print your images, you could create your own gray card as follows:
- Open up a photo taken with your camera in Photoshop. This ensures that the correct color profiles are in your image file.
- Delete the image, and fill the frame with 18% gray.
To get 18% gray, open the colour selector in Photoshop, and choose a
saturation of 0%, combined with a brightness of 82%. That's the correct
- Send the file to your printer, and take it with you on shoots.
The Apple iPhone 4 has a great camera, but it's struggling with white
balance. By using a grey card, I can ensure that the money is
well-balanced. This is the before shot
The key thing here is that your 'gray card' may not be perfectly neutral, but the important thing is that your printer thinks it is neutral - so if you colour balance your photographs to this particular card, your images should come out neutral when you print them next. There may be some difference from printer to printer (some printers may print out slightly warmer or colder images), and this is why gray cards printed on one printer aren't transferrable to another.
It could be argued, of course, that if you're serious enough about white balance that you are going to use a gray card, then you may as well buy a set of gray cards that are definitely perfectly colour balanced, but having a home-made set of cards is much better than shooting without anything, so it's a great place to start.
How do you use a gray card?
By using the known neutral grey as a sample, I can ensure that the photo is perfectly balanced
Whatever you've decided to use as your gray card, the way you use it is pretty simple:
- Set up your lighting
- Place your 'gray card' in the shot
- De-focus your camera a little and take a photo. This ensures that you capture the colour, and not the texture, of your gray card
- Remove the gray card, and take photos as usual. Every time you change the lighting, go back to step 2.
- When you've imported your photos into your favourite software package, use the gray card as a 'sample' to set a custom white balance.
- Copy the white balance across to all the other photos in the set - or until the next time you've photographed your gray card.
You can now sit back in the knowledge that all your photos have the same white balance. If it turns out that it is still slightly off, you could adjust it further, and then copy that white balance profile across to the other photos in the shoot.