Restoring a Masterpiece – the magic of custom white balance
Since I always shoot in RAW, I almost always have the camera set on auto white balance (since I can change it during Lightroom processing). My Canon 50D does a fair job with the white balance, though I usually have to bump the purple a bit (the images are a bit green). I’ve just picked up a Canon 6D (more on this in a later post), and the auto white balance seems to do even a better job. However, in certain situations, the auto white balance setting is totally fooled. Such was the case when I shot in the Metropolitan Museum of Art in New York and the Reina Sofia Art Museum in Madrid on my recent trip. It seems that my camera, if not most cameras, have a hard time with artificial light – often because there are multiple light sources (with different color characteristics) plus colored reflections off painted walls.
I suppose a quick primer on the color of light and white balance is needed (if you know about this stuff, skip this paragraph). All light has color. Daylight is naturally a bit yellow and warm. However, the same daylight in the shade is often blue because of the light coming from a blue sky. Light from tungsten bulbs is very warm and orange-yellow; light from fluorescent bulbs is green. The human eye does see these colors, but the human mind overrides what we see because the mind “knows” what color things are supposed to be and corrects for the “wrong” colors produced by the light. For example, snow is white, right. So when we look at a snow field in the shade on a sunny day, we see white snow; but in reality, the snow is blue in color. Same for a white piece of paper being lit by a tungsten lamp, it looks white, but in reality, it is colored orange -yellow. (Want proof? Try this experiment. Take a plain white piece of paper. Set it upright against the base of a table lamp with a tungsten bulb by a window. The paper should look white. Now, go outside [preferably at dusk, while there is still light in the sky] a ways off from the house and look back in the window at the paper. It should look orange or yellow tinted. This is because your mind is now “correcting” for the outside light, not the inside light.) While our minds can do this nifty little trick, cameras cannot. This is why digital cameras have white balance settings (and film cameras have different types of film for different light conditions). The white balance setting attempts to correct for the color of the light to make white white, black black, and grey grey. If you shoot JPEGs (instead of RAW), it is important to get the right white balance setting, or you may end up with color tints you don’t want (for example, using a daylight setting in the snow example above will result in blue snow in your image).
White balance settings in cameras are far from perfect. Often a scene is lit by more than one type of light (a scene with significant areas of both sunlit and shaded subjects for example). This is why I like auto white balance and shooting in RAW – the camera makes a guess, but if it is wrong, I can easily fix it.
However, sometimes I have no idea what the color of the light and no idea what the true color of the subject is. In these cases, it is difficult to get the color right. In these situations, following best photographic practices, you should set a custom white balance for your camera (many digital cameras have this option, it typically involves taking a photo of a white or 18% gray piece of paper. Alternatively, you can take your image of the paper with any white balance setting, then in Lightroom, correct the white balance by using the white balance eyedropper tool [also known as the white balance selector tool] on the paper). While it doesn’t take very long to set a custom white balance, it is only good for those exact light conditions. If you go to a different room, say in an art museum, you need a new custom white balance. Needless to say, I’m typically not that dedicated. So when in the art museums on my trip, I just used auto white balance and thought I’d try to correct later.
When I looked at the art museum photos after the trip ended, they typically had orange color casts, as in the examples here (Girl in the Window by Dali from the Reina Sofia Art Museum, and By the Seashore by Renoir and The Dance Class by Degas both in the Metropolitan Museum of Art). In Lightroom, I played with the white balance, but couldn’t seem to find a setting I liked.If I only had a neutral color (black, white, or grey) in the images, I could use the Lightroom’s custom white balance eyedropper tool and correct the color cast. My frustration was made only worse by the realization I had no idea what color Degas, Picasso, Renoir, Dali, or Van Gogh, etc. intended in their paintings, even for those areas that looked white, black or grey.
However, I soon figured out how to restore the correct color to the art masterpieces. It is my habit, when taking photos in a museum, to also photograph the explanation for the exhibit I’m photographing so I can remember exactly what it is. So in this case, when I took a photo of a painting, I also took a photo of the explanatory card next to it listing the painter, name of the painting, etc. Whether on purpose or not, it turns out, at least in these two art museums, the explanatory cards are printed on neutral-colored papers, and being next to the paintings, they are lit by the same light source.
With this realization, in Lightroom I opened the card photo for a particular painting in the Develop module and used the eyedropper tool on the card paper. Then copying the white balance settings, applied the same settings to the photo with the painting. It was as if magic, suddenly the colors popped and the paintings looked even better than I remembered them in the museums. Masterpieces restored by the magic of custom white balance.