Image processing method, automatic image printing method, and automatic printing apparatus nozzle

A nozzle for an automatic printing apparatus provided in the automatic printing apparatus for automatically printing an image on a target surface of a structure, the nozzle comprising:

• a nozzle tip including an ejection hole for ejecting ink;
• a main body part configured to fix the nozzle tip to a predetermined position, the main body part including an inlet passage, through which ink is introduced, that is configured to communicate with the ejection hole, a recovery passage configured to communicate with the inlet passage so that ink remaining in the inlet passage is recovered, and a compressed air passage for compressed air to be supplied so that the compressed air is ejected around the nozzle tip;
• and
• a piezoelectric part disposed in the main body part and configured to cause closing and opening of the ejection hole to be repeated by repeating elongation and contraction according to an applied voltage so that the ink is ejected through the ejection hole.