Histogram Pane displays distribution of pixels at each level of basic colors (red, green and blue) intensity. This graph can be used to reveal under- or overexposed photographs. It can also be used to verify white balance.
This pane window can be accessed through the View menu: View/Panes Windows/Histogram.
Note: unlike the Histogram tool this pane window uses thumbnail image to calculate the histogram. It is fast but may be less accurate than the Histogram tool. Accuracy of this histogram can be greatly improved by turning on ‘Generate thumbnails...’ in the advanced settings window.