Managing Color

As well as communicating with one or more renderers, Katana also reads in image data from a number of different formats. Managing the color of the data within Katana is accomplished through the OpenColorIO standard, originally developed by Sony Pictures Imageworks.

A typical workflow within Katana involves:

1.

Reading in the images from various formats, such as DPX, TIFF, or OpenEXR.

2.

Converting those images into the scene-linear colorspace.

This is handled automatically by Katana as long as the filenames use the OpenColorIO naming scheme. Files should use a suffix denoting the file’s colorspace, for instance: beautypass_lnf.exr (for a 32-bit linear file). For further details, see the OpenColorIO standard at:

http://opencolorio.org/

3.

Rendering within the scene-linear colorspace.

4.

Compositing and manipulating the images in scene-linear colorspace.

Note:  Compositing with image data that has not been converted yields inconsistent results.

5.

Viewing the scene-linear image data through a device-specific look-up-table (LUT) in the Monitor tab. The LUTs can include additional manipulations to show the image data converted to film or log (or any other potential output if you have the correct LUT) so you can see the image as it would display in that target’s colorspace.

6.

Writing the file out, specifying the colorspace to use in the relevant node. Use the rendererSettings.colorSpace parameter in the RenderOutputDefine node for 3D renders and the image.colorspace parameter in the ImageWrite node for 2D composites. Make sure colorConvert is enabled in both cases.

This is a best practice guide on how to work within Katana. That said, it is perfectly possible for you to work outside the OpenColorIO standard or even manipulate your images within log or some other colorspace. However, doing so forces you to manage all image manipulations manually.