self-portrait; picture painted by oneself
Refers to a painting or drawing made by the artist of themselves. More common in artistic or formal contexts; in casual speech, 自画像 (じがぞう) is often used.
He exhibited his self-portrait at the exhibition.
This self-portrait was painted when I was young.
自画自賛 is a set four-character idiom meaning 'to praise one's own work,' not an actual painting, so it should not be confused with 自画, a self-portrait itself.
Compound of 自 (self) and 画 (picture, painting). The reading じが is the on'yomi of both characters.