Pinxit mea

The buzz now is the picture found in Basilicata, a supposed self-portrait of Leonardo da Vinci with the inscription pinxit mea, which is routinely translated as painted by myself. I just don't see how they have come up with such a translation. Pinxit is the third person singular of perfect indicative of pingo, pingere (to paint). Mea is the feminine singular nominative or neuter plural nominative/accusative of meus, mea, meum (my/mine). It thus literally translates as (He/she) painted my things/mine. For it to to mean painted by myself, it would have to be pictus/picta/pictum a me.

On second thought, mea could also be the subject of the sentence (mine painted), mine being my hand (manus mea pinxit) or my right hand (dextra mea pinxit).