Automatically adjusts the contrast of the alpha channel so the alpha channel stretches the full range from transparent to opaque.
If the source image has limited contrast, using Auto
Contrast ensures you can get the maximum effect from the alpha
channel.
Particularly in situations where it is difficult to use the
"Brightness/Contrast..."
filter.
Use this filter to automatically stretch the contrast after
applying the "Gaussian
Blur..." filter.
This is especially useful if you're using Smart Objects or
actions.
This filter has no settings.