6.15 Calling VIPS functions

You can call any VIPS operation which has the following properties:

• There must be at least 1 output argument. If there’s a single output argument, that becomes the value of the function. If there is more than one output, then the function returns a list with the outputs as members.
• The output arguments must all be one of:
  • IM_TYPE_DOUBLE,
  • IM_TYPE_INT,
  • IM_TYPE_COMPLEX,
  • IM_TYPE_STRING,
  • IM_TYPE_IMAGE,
  • IM_TYPE_DOUBLEVEC,
  • IM_TYPE_DMASK,
  • IM_TYPE_IMASK
• The input arguments must all be one of the types above, or IM_TYPE_DISPLAY. If an argument is an input display, nip2 passes in its current display structure, it does not take a display from your program.

When nip2 starts up, it loads any VIPS plug ins it can find on its data search path. You can call functions from plug ins in just the same way. For information on writing plug ins, see the VIPS Manual.