Required, But Unspecified
No pixels, no millimetres, no file limit.
K-ETA takes a photo upload — that much is certain, because Korea's own FAQ answers a question about uploading a photo while wearing a hijab, which would be a strange question about a form with no photo field.
What Korea does not publish is any dimension for it. Neither the application guide nor the FAQ states a pixel minimum, a millimetre size, a file-size ceiling or a background colour.
We are not going to invent one. This site shows the Korean visa frame as a working default and says openly that it is a default rather than a requirement — the same position we take on the US ESTA, which also asks for a photo without specifying it.
Practically, that means the check is whether your face is identifiable. Face the camera, keep the whole face visible, use even light and a plain background.
