Highest Quality Capture: Workflow Phase I - Black and White in Photoshop CS4 and Photoshop Lightroom - page 54

Example 7. High Key Image with Highlight Preference
The image of the white dress is an excellent example of a “high key” image,
where almost every value of data is plotted toward the right side of the
histogram. This histogram tells us many things about the exposure for this
image. Most importantly, we can see immediately that highlight information
has been preserved in the exposure, as the stack of data does not exceed
the right side of the histogram chart. There is a long thin trace of information
across the bottom to the left side, indicating that there are few pixels with
darker brightness values. The information does not slam to the left, indicating
that we have maintained the shadow detail (although there is very little)
without clipping.