The white point determines the color balance of an image. When you are manually specifying color transforms, the white point may need to be adjusted depending on both the illumination of the original scene and the conditions under which the output is viewed — this process is also variously known as chromatic adaptation, white balancing, gray balancing, or neutral balancing.
In most cases, you do not need to separately adjust the white point of images yourself — it is simply a matter of choosing the appropriate transform. The transforms supplied with Autodesk Color Management automatically make the proper white point adjustments for display and output, as well as when converting between color spaces with specified white points. For example, the RRT+ODT/ACES_to_sRGB transform includes a conversion from D60 (ACES 2065-1) to D65 (sRGB). The description tags in the metadata of the color transform files provides detailed information about the white point that each transform is intended for.
However, you may need to compensate for a projector or display calibrated to a different white point, or mix images that are intended for different adaptive white points. In these cases, you can apply the transforms in the whitepoint/ directory. Before doing this, first make sure to convert the images to the CIE-XYZ color space (either scene-referred or output-referred linear encoding).
White point issues for digital cinema projectors (and hence DCDMs) are particularly complex since there is both a calibration and a creative white point. The calibration white point is the white point that the device is calibrated to. However, in a dark theater there are no other light sources to affect adaptation, so the creative white point may be different.
For example, many people find the DCI white point used in digital cinema standards too green. So while theaters must still calibrate their projectors to this white point, neutral objects in a scene may be portrayed to another ("creative") white point such as D60. You can achieve this by using a transform such as RRT+ODT/ACES_to_DCI-D60 as the output transform, or by explicitly converting the white point yourself using the transforms in the whitepoint/ directory.
Sometimes this technique is also used on video monitors when you want to match the white point of another device without actually recalibrating the monitor to that other white point. For example, if you have a monitor in a dark projection room, the colors on the monitor will not match the projected colors because the white points are different. To make the monitor colors match, you must convert the white point from, for example, D65 to DCI. Once this is done, neutral colors on the monitor no longer correspond to equal code values but rather to whatever code values are required to make the desired white despite the different calibration white.