The Histogram tool displays detailed pixel intensity information about the image or a channel.
The main area of the Histogram window is the graphical representation of the intensity levels across the entire luminosity range for the image. Ranges can be selected with the mouse by clicking and dragging the range from within the histogram.
Histogram Tool Settings
The Information on Channel button allows the selection of a specific color channel to show information about.
Value: Displays pixel intensity information for all channels.
Red: Displays intensity information about the Red channel only.
Green: This option ensures that only Green channel information is shown.
Blue: This setting displays only the information regarding the Blue channel.
Mean shows the average intensity of the selected range of pixels.
The Std Dev label shows the difference of the square root of the squared sums of all the selected data points from the Mean.
The Median value represents the middle value of the selected range.
The Pixels value is the total number of pixels counted in the image. It is equal to width multiplied by height.
Intensity displays the intensity for the selected range of values.
Count shows the number of pixels that have been selected within the selected range of intensity levels.
The Percentile count indicates the percentage of pixels that are currently inside the selected range.