DPP Histogram, How To Use

I'm still wondering this after playing with DPP for a bit now. I understand kinda how to interpret the histogram on the camera itself, when its over or underexposed, and I'm sure DPP works the same.

In this example though, my shot is slightly overexposed. I'm assuming the high peaks are whites or high contrast? Anyways, using this histogram in DPP, how do you know where to bring it balanced too using the 0.0 in the middle if I wanna adjust the brightness a few stops? I guess I've always been confused by that. To which peak do u kinda set it to, or do you eyeball it more or less?

Thanks in advance for any direction!

The fact that no highlights are blown (none of the curve pushes against the right side/white point) it means you are pretty "free to roam". You can pull the Brightness back a bit if you want, or you can bump Contrast a bit and pull back the Highlights a bit -- it really depends on what gives the most pleasing look. You have some darker shadows that you probably don't want to black out, so making sure you don't do that comes into the equation -- too much contrast can have that effect.

So, since there is nothing to "rescue" you have leeway to play. I don't know if there is a "right" way to approach this as much as getting the results that look best to you which means typically a bit of a mix.

A histogram is a graph with the horizontal axis being tones from absolute black on the left to absolute white on the right. The vertical axis is the number of pixels with that tone. A peak just means there are a lot of pixels the same tone, nothing more. The overall contrast is indicated by the horizontal spread of the graph - the distance from the darkest tone to the lightest. If the histogram runs off one or both ends that is bad because it means that the scene's contrast is greater than the camera can capture (when it runs off both ends) or the shot has been underexposed (off the left) or overexposed (off the right) to the point where data is missing. In your shot, however, although it is overexposed it is not so badly overexposed that the histogram hits the right end and simply moving the Brightness slider to the left will fix that.

I do eyeball it, but I also use the numerical readout at the bottom of the screen plus my knowledge of what the numbers should be. Those numbers are on an 8 bit scale so they go from 0 to 255 and 128 is a medium tone. I know that Caucasian skin is one stop lighter than medium so in this case I would want to see the brightest part of the boy's face to have values in the area of 220/180/160.

You seem to think that you need to properly position the peak, but that's not so.

The peak's location tells you which tones are the most frequent in the picture, but it doesn't necessarily include the tones that are the most important in the image. Which parts of the image will contribute to build the peak depends entirely on the image itself, so there is no rule where on the scale the peak should be.

A portrait with lots of a dark wall in the background will have the peak (reppresenting the expanse of wall tones) pretty much to the left, while the skin tones (the important part of the image) will be included somewhere in the lower-right part of the "bell".

As Elie said, it's the tails of the histogram that you have to mind, so as not to clip/block highlights or shadows while you push-pull the histogram to suit the most important features and the image overall. The histogram will slide sideways, stretch or compress in response to your edits, but the location of the peak is irrelevant, as long as the image looks fine. Check the histogram under the RGB tab to see the effect of your edits.

With the DPP++ plugin, you can watch the RGB (output) histogram while working in the RAW tab.
http://digitol.free.fr​/doku.php?id=dpppp:hom​e