Channel Resolution

From ZBrush Info

Each channel has an associated resolution, which is a measure of how many gradations of intensity it can represent. The higher the resolution, the more accurately visual information can be stored. For example, many image file formats allow only 256 intensity levels for each color channel. Such a format can represent only 256 intensities of pure red (the blue and green channels will be 0 if a pure red is being shown), which is usually enough to produce decent onscreen images, but is far less than the range perceptible by the human eye. If you see phrases such as “channel width”, “bit depth”, “channel format”, and the like, chances are they are all referring to properties affecting channel resolution.

The resolution of a channel is determined by how much data is stored, for each image pixel, in that channel, and this is normally expressed by the number of bits (binary digits) stored at each point. Here’s a summary of how the number of bits corresponds to the resolution of a channel:

Bits	Intensity Levels
8 bits	256
16 bits	65,536
32 bits	4,294,967,296

Other things being equal, the greater the resolution of the channel the better.

32 bit formats are usually stored in what is called a ‘floating-point’ format. In practical terms, this allows a further degree of accuracy under most circumstances, and with respect to the DE, simplifies some aspects of exporting alphas.

The most likely advantage you’ll see when using the 32 export format is that, once a satisfactory alpha depth factor has been determined for your export needs (set by the Alpha Depth Factor slider in the Alpha palette), you will not need to change it when subsequently exporting new versions of the same displacement map. You may also find that you do not need to adjust the alpha depth factor even when exporting different displacement maps.

We recommend exporting in a 32 bit format, if your target program can read this format.