A perhaps more useful global tone mapping method is gamma compression, which has the filter formula_4 where and . This function will map the luminance "V" in the domain formula_5 "γ" regulates the contrast of the image; a lower value for lower contrast. While a lower constant "γ" gives a lower contrast and perhaps also a duller image, it increases the exposure of underexposed parts of the image while at the same time, if , it can decrease the exposure of overexposed parts of the image enough to prevent them from being overexposed.