A photonic instantaneous frequency measurement receiver based on frequency to optical power mapping is proposed and experimentally demonstrated. One channel of a dense wavelength-division multiplexer (DWDM) is used as an optical filter to establish a power ratio function related to the frequency of the microwave signal. Different from most optical filters, the DWDM filter features smooth and quasilinear roll-off over a wide bandwidth. With the help of a laser of good wavelength stability and a bias controller, large measurement range and high accuracy are simultaneously achieved without multi-step operation. The instanstaneous frequency measurement receiver can measure the frequency with an accuracy of 0.2% of the signal frequency in the range of 1-40 GHz over 1.5 h in the experiment.