-// Note: I don't know of any cards that round off wrong (well, outside
-// our tolerance) and do not have this extension.
+// - The measurement is done on linear 8-bit, not any sRGB format,
+// 10-bit output, or the likes.
+// - This only covers the final pass; intermediates are not covered
+// (only relevant if you use e.g. GL_SRGB8 intermediates).