ImageAdjust

ImageAdjust[image] adjusts the levels in image, rescaling them to cover the range 0 to 1.

ImageAdjust[image, {c, b, g}] adjusts contrast c, brightness b, and gamma g.

Examples

Adjust image levels:

img = ExampleData[{"TestImage", "Lena"}];
ImageAdjust[img]

Increase contrast and brightness:

ImageAdjust[img, {0.5, 0.2}]

Please visit the official Wolfram Language Reference for more details.