Sunday, March 29, 2009

Correcting for White Balance

I had a friend wonder at what type of camera I had since she thought my pictures turned out better than what she got. I did mention my expensive lens that I use but of just as much importance for any picture with any camera is lighting (that I will try and discuss later) and white balance.

So I thought I would discuss white balance a little bit. I took some pictures of my grandson Lucas in the bathtub recently and you can see the result in the first picture. Two things that have to be said about the first, very yellow picture. Most cameras have an AWB (auto white balance) setting that probably does a fairly good job of figuring things out. In the case of this picture, my WB was set at sunlight and this picture was taken with no flash and so all the light came from the regular light in the bathroom. This is what gives it the yellow glow. The second thing is that I shoot in Camera Raw so I wasn't worried because the WB can be changed in software. RAW requires a software step but it also gives you a lot more latitude for correction as we will see.

In order to attempt to simulate what might happen if I shot in jpeg format and then tried to color correct, this next picture is the result. It required a bit more work in software than the final picture below, but the result is much better than the yellow one above. I use Adobe Camera Raw software to do my corrections and the quick way is to grab the WB eyedropper and click on something that should be white or gray in the picture. A bit of playing with sliders got what I thought was the best. With a jpeg shot, the ability to adjust is more limited than in raw. I still see a bit of yellowish/green tint to the picture but it is much improved.

This final picture is the raw shot that initially looked like the first picture above. For this one, all I did was take the eyedropper and click on the bathtub to get what I think is the most natural look. (I did brighten this a little bit so it had the same brightness level as the other two pictures but it was a 5 second tweak with the levels adjustment tool in Photoshop.) This is the major advantage I find in shooting RAW because I don't worry about what my WB setting is. I still should because it could save a step in the workflow if I got the WB right in camera but I don't worry too much about this.

Not every camera has the capability of shooting in RAW and not every RAW mode gives the same flexibility that the SLR level camera has. Additionally, it does require extra work to process. RAW is the equivalent of the negative from the old film days that had to be processed first before prints were made.

You can see that white balance is quite important and you should do some experimentation with your camera to see the impact. Start with auto white balance and shoot in daylight, shade, with flash (pretty similar to daylight), fluorescent and tungsten (regular light bulbs). Then do the same with your WB set on sunlight or flash and compare the shots to see how effective the AWB is. Then, set the WB for each lighting condition. You will then have a set of comparison shots that will tell you whether AWB works in your camera or whether you need to manually set the WB to the proper conditions.

Hope this helps understand this. There are far better discussion about this around the net so do a search if you want to learn more.