Auto Levels

The Auto Levels command - from the Adjust section of the Image menu - applies an automatic tonal readjustment of the image by repositioning the endpoints of the tonal range. The tones are readjusted to fit in between the new endpoints. The effect is to increase the contrast in the image.

The lightest and darkest pixels of the image are reset as white and black respectively, and then the intermediate pixel values are redistributed proportionately. The dark values get darker and the light values get lighter, hence causing the image to have higher contrast and greater color saturation.

For more information on adjusting levels, see Levels.