Function
This applies a contrast change on the image, with a smooth falloff on both the
low and high ends. You can also move the center of the contrast curve up and
down (i.e., moving it down makes your overall image brighter). Note that this
contrast is based on the luminance of the pixel, so it balances red, green,
and blue, and you therefore won't shift your hu. This means an image with strong
primary colors will look differently from the an image with the same values
in a ContrastRGB, which
evaluates each channel separately.
Also note that we have a rolloff built into the contrast function, giving you a smooth falloff at the ends of the curve. This is controlled by the softClip parameter.
Parameters
|
Type
|
Defaults
|
Function
|
value |
float
|
1 | The contrast value. A higher value means it pushes your RGB values towards 0 and 1. A value of 0 means no change. A lower value means low contrast. |
center |
float
|
.5 | This is the center of the contrast curve. A lower value means a brighter image. |
softClip |
float
|
0 | This controls the drop-off of the curve. When it is increased to 1, you have maximum smoothness of the curve. |
image ContrastLum( image In, float value, float center, float softClip );
image = ContrastLum( image, value, center, softClip );
Command Line
shake -contrastlum value center softClip
shake lisa.iff -contrastl 2
shake lisa.iff -contrastl 2 .3
shake lisa.iff -contrastl 2 .8
shake lisa.iff -contrastl .8
See Also
ContrastRGB, Gamma,
Add, Mult,