The HV30 White Balance, Part 2

Okay, now the histograms for our white balance experiment. The first four look similar in the red, green, and blue channels, but there is a significant difference in the luminance (black graph) channel, with more spikes for the Custom white balance setting (unsurprising given it responds to whatever you put in the lens while setting it). It is different from the fully-automated setting, but the spikes are in the same neighbourhood, as is the bump to the left of the spikes.

The two fluorescent settings differ in the luminance channel more than they do in the 3 colour channels. This makes sense as the fluorescent-corrected is intended for lights shifted from the greens of regular fluorescent lights (measured as 4100-4400 K colour temperature) towards the bluer temperature of sunlight (5000-6500 K). Shooting in real daylight creates one spike (or 3 shoved together?) for the daylight-corrected setting, but 3 distinct spikes for the conventional fluorescent setting.
Looking at the actually Daylight setting, it resembles the fluorescent setting in terms of the luminance, and not the corrected one. Interesting, and not what I expected.

The Shade setting pushes the 3 spikes of the Daylight setting together, with nearly identical colour channel readings for both. The Cloudy setting, by comparison, has luminance spikes somewhere between Daylight and Shade, which makes sense.
Finally, the tungsten setting, which is designed for the 3000K colour temperature of the halogen incandescent bulb (I’m guessing the 2700K average for conventional incandescent are probably okay with this setting, too). I’ve grouped it with the two fluorescent settings (which I’ve misspelled, perhaps reflecting my past work in the restaurant business…) to see what the 3 artificial light settings do.

As the screen cap from last time shows, this setting spikes in the blue channel farther to the right than the other settings. The three green channels are quite similar, but the tungsten setting pushes the red channel towards the dark side—not surprising given the light bulb gives off a distinct orange-yellow glow and tends to tint everything towards the red. The luminance graph is different, too, with that ragged, wide spike in the bright end of the scale—I’m guessing the heavy shift in the blue channel means the luminance spike moves over, too.

Based on this third histogram comparison, I’d say that the more corrective the white balance setting, the more spikes and shifts in the luminance and colour graphs. The Tungsten and Fluorescent settings correct strong red and green shifts, respectively, by changing the image much more than what we see in the three natural light settings and the daylight-corrected fluorescent settings.

The most detailed histogram is the custom setting, which I had set by zooming into an area of virgin snow and pressing the white balance button to set the camcorder. Going forward, I’ll carry a grey card (backed with a white card) with me in order to manually set the white balance, relying upon the presets only when I forget the card or it’s not practical to shoot one in advance (such as when I shoot a stage show and don’t have the opportunity to set up properly).