Resize image to exact pixels, cm or inches
For forms that give the size in centimetres (like “3.5 cm × 4.5 cm”) or pixels. Set the size, the DPI and, if your form has one, the KB limit.
How the size is worked out
Pixels = centimetres ÷ 2.54 × DPI. At 200 DPI, 3.5 cm × 4.5 cm is 276 × 354 pixels. If your form gives only centimetres, any common DPI works; the DPI value is also written into the file, so it shows the right size in centimetres when printed or checked.
With a max KB, the quality is lowered just enough to fit. With a min KB, a small file is padded up to the minimum without changing the picture. Turn off “Keep shape” to set width and height separately (the picture is stretched to fit).