Histogram curiosity

[lordfly]

So I'm editing the pictures I took last night (with my new nifty fifty prime lens, woo), and as usual, I do most of my quick edits in Lightroom while looking at the histogram.

I've noticed something odd, though, and would love to hear some insights on this: On a lot of my unedited pictures, the histogram normally has three peaks of similar size and shape; red, green, and blue. They are normally out of alignment with one another. However, when adjusting the white balance (normally down, so the tungsten doesn't make everything look orange), the peaks all start to align.

Is this something I should be going for? I normally just eyeball the WB (or color pick it if I'm in a rush); are the aligned color peaks technically the "correct" white balance? Or is it just a histogram curiosity that I can ignore?

 

[Overread]

Thus far I've seen a lot of different kinds of histogram and as far as a I've been able to work out the actual shape is going to be unique each time and the key is to use the histogram to help ensure that one does not have over or under exposure (except where specifically wanted of course) both in the luminosity and in the three colour channels.
One can also use it during the shooting phase to try to "expose to the right" as much as possible when one has the option.

Otherwise as I said the shape is nearly always going to be unique depending on the scene and the light shown

 

[Syco]

The red, green and blue peaks are usually out of alignment, the degree to which depends on the lighting. Adjusting the WB brings them closer together. I'm not sure if Lightroom allows you to do this, but in Elements I routinely adjust Levels of the R, G and B channels individually. This usually brings the WB into compliance. Other people use the eye-dropper white balance tool.

 

[KmH]

A histogram is a graphic representation of the distribution of the number and luminosity of the pixels in an image.

A digital image has 3 color channels: Red, Green, and Blue.

The vertical axis of the histogram represents how many pixels and the horizontal axis represents the luminosity of the pixels.

If you align the peaks horizontally, you are aligning the luminosity.

 

[clanthar]

Is this something I should be going for? I normally just eyeball the WB (or color pick it if I'm in a rush); are the aligned color peaks technically the "correct" white balance?

No. If you photographed a monochrome world or took a photo of a b&w print then the color peaks would line up when your photo was correctly white balanced. If your photo had a color cast the miss-alignment of the peaks would indicate that. However in a color world, the histogram for each color channel is unique and should stay that way. If you were able to take a color photo and then force the three color channels to all line up you'd have a monochrome photo.

In fact try that. Open a color photo, leave it's structure RGB, and desaturate it -- the color peaks will line up.

Joe