enum depth{
  depth8u  = 0, /**< 8Bit unsigned integer values range {0,1,...255} */
  depth16s = 1, /**< 16Bit signed integer values */  
  depth32s = 2, /**< 32Bit signed integer values */
  depth32f = 3, /**< 32Bit floating point values */
  depth64f = 4, /**< 64Bit floating point values */
  depthLast = depth64f
};