A frequency-selective technique is proposed to improve the performance of joint-transform correlators. In this technique, the useless part of the Fourier transform interference intensity for creating the correlation signal of the joint-transform correlator is removed. Two architectures to achieve this goal are also presented. It is shown that dramatic improvement (as large as 200%) in the autocorrelation peak amplitude of the joint-transform correlator is possible by means of the proposed technique. Similar to the bipolar joint-transform correlator, the bipolar frequency-selective joint-transform correlator has a delta-function-like autocorrelation signal. In addition, it provides similar discrimination ability and noise performance to the bipolar joint-transform correlator.