The 3x4cm Format
30mm wide by 40mm high — smaller than the ICAO standard.
Qatar's visa and Hayya card photos use a 30x40mm frame, commonly written as 3x4cm. It is shorter and narrower than the 35x45mm photo most other countries ask for, so a spare ICAO photo will be the wrong proportions.
Because the frame is small, your face needs to fill 70-80% of the height for the features to be usable. A photo taken from too far away leaves your face too small to pass.