Some digital compositing systems, especially those geared for video work, are optimized for processing exclusively 8-bit elements (that is, images with 256 intensity values per channel). Other systems allow for the mixing of 8, 16, and 32-bit elements.
For Nuke products, which began as a film effects tool, image quality is paramount. Thus, they support the processing of exclusively 32-bit-per channel elements (elements with lower bit depths are converted to 32 bits per channel upon import). Thirty-two bit support allows for a much richer palette of colors and floating point precision in all script calculations. In practice, this means that Nuke products carry out every operation - from an increase in gamma to a transform - with much greater accuracy than a lower-bit-depth system.