__kernel void gegl_invert (__global const float4     *in,
                           __global       float4     *out)
{
  int gid = get_global_id(0);
  float4 in_v  = in[gid];
  float4 out_v;
  out_v.xyz = (1.0f - in_v.xyz);
  out_v.w   =  in_v.w;
  out[gid]  =  out_v;
}