Working with Multiple Image Formats in Nuke

Nuke supports multiple file formats, such as Cineon, TIFF, OpenEXR, HDRI, and RAW camera data (via the dcraw command-line program), and allows you to mix them all within the same composite. By default, Nuke converts all imported sequences to its native 32-bit linear RGB colorspace. You can, however, use the Colorspace node to force one of several color models, including sRGB, Cineon, rec709, gamma 1.80/2.20, HSV, or HSL. The Log2Lin node lets you convert between logarithmic and linear colourspace (and vice-versa).

8-, 16-, and 32-Bit Image Processing
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, which began as a film effects tool, image quality is paramount. Thus, it supports the processing of exclusively 32-bit-per channel elements (Elements with lower bit depths are upconverted to 32 bits per channel upon import.) Thirty-two bit support allows for a much richer palette of colours and floating point precision in all script calculations. In practice, this means that Nuke carries out every operation—from an increase in gamma to a transform— with much greater accuracy than a lower-bit-depth system.