We introduce a conformal phosphor coating technique for white light-emitting diodes (LEDs) using image-processing-based maskless lithography (IP-ML). The use of IP-ML allows real-time recognition of LEDs, which enables the generation of photo-patterning masks on a spatial light modulator by means of image processing, making the process suitable for a chip-level conformal phosphor coating with contact openings. This automated photolithographic chip array coating process enables phosphor coating onto chips with a consistent thickness, and the chips treated using this method show a narrow color distribution in which the chromaticity is controllable by varying phosphor thickness and concentration.