Astra Image can give you many statistics about your image. This can be very useful when determining image quality, or for advanced image analysis.
Display range: this option sets the numeric range of the statistics. For example, when set to 8-bit (0..255), the statistics will be displayed with a minimum value of 0 and a maximum of 255; when set to Float (0..1), the statistics will be displayed with a minimum value of 0 and a maximum of 1.0, and so on.
Include pure black and white values: when this option is checked, all pixels in the image will be included in the statistics calculation. When unchecked, pixels that are pure black and white will be excluded from the statistics calculation.
The statistics list shows the various calculations for each channel in the image.