Editing Digital compositing (section)

==Software ==

The most historically significant nonlinear compositing system was the [[Cineon]], which operated in a logarithmic color space, which more closely mimics the natural light response of film emulsions (the Cineon System, made by [[Kodak]], is no longer in production). Due to the limitations of processing speed and memory, compositing artists did not usually have the luxury of having the system make intermediate conversions to linear space for the compositing steps.  Over time, the limitations have become much less significant, and now most compositing is done in a linear color space, even in cases where the source imagery is in a logarithmic color space.

Compositing often also includes [[Image scaling|scaling]], [[Photograph manipulation|retouching]] and [[colour correction]] of images.

===Node-based and layer-based compositing===
There are two radically different digital compositing workflows: node-based compositing and layer-based compositing.

Node-based compositing represents an entire composite as a [[directed acyclic graph]], linking media objects and effects in a procedural map, intuitively laying out the progression from source input to final output, and is in fact the way all compositing applications internally handle composites. This type of compositing interface allows great flexibility, including the ability to modify the parameters of an earlier image processing step "in context" (while viewing the final [[compositing|composite]]). Node-based compositing packages often handle [[keyframing]] and time effects poorly, as their workflow does not stem directly from a timeline, as do layer-based compositing packages. Software which incorporates a node based interface include [[Natron (software)|Natron]], [[Apple Shake|Shake]], [[Blender (software)|Blender]], [[Blackmagic Fusion]], and [[Nuke (software)|Nuke]]. Nodes are a great way to organize the effects in a complex shot while maintaining a grip on the smaller details.

Layer-based compositing represents each media object in a composite as a separate layer within a timeline, each with its own time bounds, effects, and keyframes. All the layers are stacked, one above the next, in any desired order; and the bottom layer is usually [[rendering (computer graphics)|rendered]] as a base in the resultant image, with each higher layer being progressively rendered on top of the previously composited of layers, moving upward until all layers have been rendered into the final composite. Layer-based compositing is very well suited for rapid [[2D computer graphics|2D]] and limited [[3D computer graphics|3D]] effects, such as in motion graphics, but becomes awkward for more complex composites entailing numerous layers. A partial solution to this is some programs' ability to view the composite-order of elements (such as images, effects, or other attributes) with a visual diagram called a [[flowchart]] to nest compositions, or "comps," directly into other compositions, thereby adding complexity to the render-order by first compositing layers in the beginning composition, then combining that resultant image with the layered images from the proceeding composition, and so on.