The rules that get home-taken ID photos accepted — background, head height, lighting, and the three mistakes that trigger rejections.
Most rejections are for the same three reasons: shadows on the background, wrong head height, glare on glasses. All three are avoidable with daylight and a tape measure.
Steps
Check the spec first — countries differ (US 51×51 with 50–69% head height; China passport 33×48; Schengen 35×45 with 70–80%). The guide library has per-country pages.
Plain white or light background: a bare wall, or a white sheet stretched — wrinkles print as shadows.
Face a window (see the lighting guide); stand about half a metre from the wall so your shadow falls below frame.
Head height: measure on the wall with tape if needed. It is the #1 silent rejection cause.
No glasses if the spec allows avoiding them; if worn, tilt slightly down and check for glare in the preview.
Neutral expression, mouth closed, both eyes open, hair off the forehead if the spec requires the hairline visible.
Crop with a tool (FaceLab's ID-photo page bakes specs in), print matte, not glossy.
Reading the result
Print at the exact size with no scaling; a 5% upscale can push head height out of range. Keep a digital copy — more schemes now accept digital uploads.
Increasingly yes for digital submissions (UK app, Singapore ICA, US DS-160 upload). The capture rules are unchanged — the checker validates background and head height just like prints.