Adjust video input frames using levels.

The filter accepts the following options:

rimin, gimin, bimin, aimin

Adjust red, green, blue and alpha input black point. Allowed ranges for options are [-1.0, 1.0]. Defaults are 0.

rimax, gimax, bimax, aimax

Adjust red, green, blue and alpha input white point. Allowed ranges for options are [-1.0, 1.0]. Defaults are 1.

Input levels are used to lighten highlights (bright tones), darken shadows (dark tones), change the balance of bright and dark tones.

romin, gomin, bomin, aomin

Adjust red, green, blue and alpha output black point. Allowed ranges for options are [0, 1.0]. Defaults are 0.

romax, gomax, bomax, aomax

Adjust red, green, blue and alpha output white point. Allowed ranges for options are [0, 1.0]. Defaults are 1.

Output levels allows manual selection of a constrained output level range.

preserve

Set preserve color mode. The accepted values are:

none

Disable color preserving, this is default.

lum

Preserve luminance.

max

Preserve max value of RGB triplet.

avg

Preserve average value of RGB triplet.

sum

Preserve sum value of RGB triplet.

nrm

Preserve normalized value of RGB triplet.

pwr

Preserve power value of RGB triplet.