Triple correlation peak inspecting technique (TCPIT) was adopted for the signal processing of IR systems in detecting sub pixels or point targets. Investigations show that the signal to noise ratio (SNR) can be improved by about 23dB with the input peak SNR of 0.84 and the input power SNR of -9.73dB. The 2 D graphics method for implementation of TCPIT was recommended. Using this approach,the amplitude information of point targets can be still effectively extracted from noises with the input peak SNR lowered to 0.48 and the input power SNR lowered to -14.24dB.