gdk:pixbuf-saturate-and-pixelate (src dest saturation pixelate)

src -- a gdk-pixbuf:pixbuf object for the source pixbuf
dest -- a gdk-pixbuf:pixbuf object for the place to write the modified version of src
saturation -- a number coerced to a single float for the saturation factor
pixelate -- a boolean whether to pixelate

Modifies saturation and optionally pixelates src, placing the result in dest. The src and dest arguments may be the same pixbuf with no ill effects. If saturation is 1.0 then the saturation is not changed. If it is less than 1.0, the saturation is reduced (the image turns toward grayscale); if greater than 1.0, the saturation is increased (the image gets more vivid colors). If pixelate is true, then pixels are faded in a checkerboard pattern to create a pixelated image. The src and dest arguments must have the same image format, size, and rowstride.