The painter, tiny, in the back
Background, a short top-hatted figure beside a very tall one
Crossing the back of the room is a short man in a top hat walking just ahead of a conspicuously tall companion. The short one is Lautrec himself, the tall one his cousin, the physician Gabriel Tapié de Céleyran. Lautrec puts himself in his own painting as a small background figure and makes the height gap part of the joke, a dry, unsentimental self-insertion.