The Equalize adjustment allows you to redistribute pixel brightness values to more evenly fill the image brightness range: the brightest pixels become white, the darkest pixels become black, and the rest are distributed among different shades.

To apply this adjustment, select in the menu: Image -> Adjustment -> Equalize.

Original Image Using Equalize Adjustment
Using Equalize Adjustment


Hint: You can duplicate the layer and then fade the equalized image to blend with the original.