What ICA currently publishes
Separate eVisa requirements from PNG passport-photo rules
ICA's current Visitor Visa guidance says supporting evidence can be requested depending on an applicant's circumstances. The live public eVisa information reviewed for this guide does not publish one standard photograph rule covering every visitor, business, entertainer, restricted, special-exemption and working-resident application.
ICA does, however, publish clear requirements for PNG passport photographs: recent head-and-shoulders photos, full face, without a hat or tinted glasses, on a light-coloured background, measuring 35 mm × 45 mm. A separate current passport checklist specifies a white background and neutral expression.