Leaving white balance for post-processing. Is it a bad idea?

Question

I am new to video. I have a HandyCam (CX405). I don't like trusting in the auto-white balance because it is variable and unpredictable, but changing manually between indoor/outdoor or doing re-calibrations with a white paper can be a real pain in the neck because in that camera everything must be done through one single small button that can be pressed or pushed in four directions to navigate menus.

My idea is leaving one fixed setting (either indoor or outdoor) and then doing the white balance in the post-processing stage in blender.

I know that some things must be done right at the recording stage and if you screw up there is little you can do afterwards, e.g. using a wrong shutter speed. And I know there are some other things that are done internally on the recorded footage inside the camera and you could do them equally well in the post-processing stage manually, and I think white balance may be well be one of them because essentially consists on a numerical multiplication of the values stored in the C_R and C_B components of the video that the CMOS has already recorded. So, probably, you will not loose any information if you do the white balance later in your editing software instead of doing it in the camera.

Is that wrong? Will I regret it later?

Answer 1

Don't do white balance in post, you will regret it. The problem is that the footage your camera records is compressed. That means the sensor information is not stored in RAW, but encoded using lossy compression. The encoding algorithm uses the White Balance setting to determine the encoded color values. The problem is, the original luminosity values that are measured by the CMOS sensor aren't stored in the compressed video, only the rendered color values.

Your camcorder uses the H.264 codec, which means the encoding uses spatial (intra-frame) and depending on your recording settings temporal (inter-frame) compression. This means that some information on pixel-level is dropped as well to achieve a smaller file-size.

To be able to set the White Balance in post without losing any quality, you will need a camera with RAW-capturing capabilities. Unfortunately, for video cameras, those are still very expensive and are pretty much exclusive to professional/commercial movie making.

So yeah, set the White Balance before you start shooting. I would also recommend you set the White Balance manually instead of using the automatic white balance adjustment, especially if you are just starting out. This has a couple of benefits:

• The white balance will remain consistent for the entirety of each shot and between shots (if you don't change it too often). AWB will adjust your white balance even while shooting, so if you have some warm or cold light source moving through your image, you might get some unwanted color shifts in your recordings.
• In time you will learn to recognize how warm/cold a given lighting situation is, which is a valuable skill to have for a videographer. This will also in turn allow you to estimate what White Balance setting you need in every situation.
• You will become more conscious of the light sources illuminating your shots, as well as their temperatures. This will be helpful for your video making in general.
• Finally, you will naturally transition to using warmer/colder lightsources and White Balance settings for dramatic effect. The AWB will always try to achieve a neutral grey, which doesn't always work, but even if it does, it's still only neutral grey. Depending on what scene you're shooting, you may want to go for a warmer or colder look to convey different emotions. You can achieve those looks using different lightsources or White Balance.