Abstract: For the detection of infrared dim small targets under complex background, an infrared dim small targets detection algorithm based on wavelet packet transform is proposed. Firstly, the wavelet packet transform is used to decompose the infrared image with small and weak targets to obtain the high and low frequency node coefficients at different scales. Secondly, according to the different contributions to the target energy during the reconstruction of different node coefficients, the frequency band node coefficients in the middle of the energy distribution in the high frequency band are selected to reconstruct the image to complete the background suppression. Finally, the target image after reconstruction is segmented by adaptive threshold segmentation method, and the result of target detection is obtained. In the experiment, multiple infrared sequence images were used to verify the results. The simulation results show that the algorithm can suppress the background and cloud edge well, detect the target signal accurately, and improve the target’s signal-to-clutter ratio and contrast.

Key words: image processing； infrared image, target detection, background suppression, wavelet packet transform