Tone Mapping

Tone mapping scales the RGB values of an image, which might be too bright or too dark to be displayed. This is done by finding the tonal range of the output image which is based on the scene’s “key value” or “neutral value”. The log-average luminance is calculated which is used as the key of the scene. The image is then scaled using this log-average and alpha. Alpha determines the brightness or darkness of the image. Below is an image without using any tone mapping and is followed by two images which uses tone mapping. The alpha corresponding to the images is given.

Before Tone Mapping:

After Tone Mapping (alpha = 0.18):

Alpha is 0.40: