Classifying a faint mark as a band can require human judgment; the speaker says a scientist would classify the bottom mark at twenty as a band, although some viewers might see a smudge.

“And there's a bit of human taste to this too. So, um, if we go back, um, we can see that this bottom band at twenty, um, to some might look like low or it may look like a smudge, but if you were to ask a scientist, this is very firmly a band.”