-// We currently support the 8-bit ranges only, since all of our Y'CbCr
-// handling effects happen to support only 8-bit at the moment. We will need
-// to fix this eventually, though, with an added field to YCbCrFormat.
+// Thus, you will need to specify the actual precision of the Y'CbCr source
+// (or destination); the num_levels field is the right place. Most people
+// will want to simply set this to 256, as 8-bit Y'CbCr is the most common,
+// but the right value will naturally depend on your input.
+//
+// We could use unsigned formats (e.g. GL_R8UI), which in a sense would
+// solve all of this, but then we'd lose filtering.