BGradient-Operator  Example 

This operator allows you to modify image-colors smoothly. It features
all methods of the  Balancing -PlugIn.
But instead of applying a fixed set of parameters to the whole
image a smooth gradient (parallel or radial) is created and
applied.

Parameters

Name        Possible Values/Unit            Description

Input       STREAM, TEMP1, ..., TEMP8       input buffer
Ouput       STREAM, TEMP1, ..., TEMP8       output buffer
Mode                                        type of balancing:
             RED                             shift the red components
             GREEN                           shift the green components
             BLUE                            shift the green components
             CONTRAST                        change the contrast
             BRIGHTNESS                      shift all color components
             GAMMA                           gamma-correction
             SATURATION                      change the color saturation
X1,         pixels                          position of point 1 ("source")
Y1
Value1      -255...255                      intensity at point 1
X2,         pixels                          position of point 2 ("destination")
Y2
Value2      -255...255                      intensity at point 2
Transition                                  type of transition (shape):
             PARALLEL                       "normal" gradient
             RADIAL                         circular shape

Since version 3.74 all numerical parameters are adjusted from within
the  Parameter-Settings -Window.

Notes
1) In "Transition=RADIAL"-mode the point 1 is the centre of the
   circular shape.
2) Because the coordinates of both points can be adjusted freely
   linear gradients in any direction can be created.
   (The current direction is indicated in the Realtime-Preview-Window.)
3) Using the brighness-mode you may fade in/out animations in
   a very impressive way.
4) The gamma-mode seems to be relatively slow. This is because lots
   of pow(x,a)-values have to calculated.
5) This PlugIn supports "parameter-dragging" from within
   the  ImageCoordinates-Window .