Detecting dim and small target in infrared images and videos is one of the most important techniques in many computer vision applications, such as video surveillance and infrared imaging precise guidance. In this paper, we proposed a real-time target detection approach in infrared imagery. This method combined saliency detection technology and local average filtering. First, we compute the log amplitude spectrum of infrared image. Second, we find the spikes of the amplitude spectrum using cubic facet model and suppress the sharp spikes using local average filtering. At last, the detection result in spatial domain is obtained by reconstructing the 2D signal using the original phase and the filtered amplitude spectrum. Experimental results of infrared images with different types of backgrounds demonstrate the high efficiency and accuracy of the proposed method to detect the dim and small targets.