According to 6.2.1a of Braille Formats 2011, all captions accompanying images are to be included. Each caption is preceded by an identifier (Cartoon, Photograph, etc). The caption uses margins 7-5 and don't required blank lines around them. If a description is required (a description is required if the caption does not adequately explain what the image is), it follows the caption (enclosed in TN indicators and using 7-5 margins). There are specific rules for transcribing cartoons - see 14.10 of Braille Formats.