= Compositing tips and tricks =

* Each node that takes a  [mask|/composite/masks]  has options to let you
  quickly perform common modifications to the mask input: resize mask to
  fit image, invert mask, and masking amount.

* Use  [Follow display/current
  mode|/ref/views/imgview#ref_imgview_follow]  in the  [compositing
  viewer|/ref/views/imgview]  to use the manipulator from one node
  while viewing the effects on a downstream node.

* Learn about the options of the  [compositing
  viewer|/ref/views/imgview] . Don't forget you can use the
  [timeline mode|/ref/views/imgview#ref_imgview_timeline]  when
  editing  [timing nodes|/composite] .

* Use the  [thumbnail flag|/nodes/cop2]  to show what a node is doing
  without re-cooking.

== Working with High Dynamic Range images == (comp_hdr)

    High Dynamic Range (HDR) images provide much more flexibility for
    compositors by providing much more color information. However, they
    also cause some problems in compositing:

    * Using color correction operations, you can easily create colors
      with negative or super-white components when doing normal color
      corrections. Negative color components can cause unexpected
      results when compositing over other images.

    * Alpha can also be drawn outside the 0-1 range. This produces
      strange results when using compositing operations that depend on
      alpha to blend (over, inside, and XOR).

    * HDR colors don't work well with the screen compositing operation,
      which will cause some odd color shifts.

    * Applying gamma to HDR images, especially low gamma, can cause
      super-whites to become extremely bright.

    * LUTs have a limited range, usually black-white. Applying a such a
      LUT can cause unwanted clipping of HDR information

    To reduce these problems:

    * Use a limit COP to clamp HDR information where it is not needed.

    * Use color curves for finer control over HDR ranges (Color Curve
      COP).

    * Convert alpha to 16bit int.