A method for measuring physiologically characteristics of user includes: using at least one light emitting unit to emit light ray including first light component corresponding to first wavelength and second light component corresponding to second wavelength different from the first wavelength using an image sensing circuit to sense and generate at least one physiologically characteristics measurement signal in response to the light ray performing an offset calibration operation upon the physiologically characteristics measurement signal to generate at least one calibrated measurement signal and, calculating the calibrated measurement signal to estimate a physiologically characteristics result.
