PDF (adobe.com)

View the histogram for a multilayered document

  1. Choose Expanded View from the Histogram panel menu.
  2. Choose a setting from the Source menu. (The Source menu is not available for single-layered documents.)
    Entire Image
    Displays a histogram of the entire image, including all layers.

    Selected Layer
    Displays a histogram of the layer that’s selected in the Layers panel.

    Adjustment Composite
    Displays a histogram of an adjustment layer selected in the Layers panel, including all the layers below the adjustment layer.