How to Photograph the Cup
Turn the cup over, let it cool, then hold it level and shoot straight down into it. Daylight works best; an overhead lamp throws shadow into the cup and the grounds patterns disappear. Skip the flash, it glares off the residue and swallows the shapes.
Get the whole inner surface in frame. The upload takes a single photo, so shooting three times from slightly different angles and picking the sharpest beats one blurry attempt by a wide margin. Take care not to disturb the grounds while turning the cup; a pattern that has slid apart cannot be read.