小目标与海空背景合成红外图像统计特性分析

针对海空复杂背景下红外小目标识别的需要，对海空背景及其小目标的红外图像特性进行了统计分析。具体分析了在有目标和无目标两种情况下3~5 μm和8~12 μm两个波段图像的均值、方差和协方差等统计特性以及图像的局部对比度、信杂比和阈值随探测距离变化的规律；同时对生成的红外热像进行了直方图分析。结果表明：随着探测距离的减小，导弹的辐射逐渐增大，到达一定探测距离时（大约8 200 m）可以从热像图中区分导弹的蒙皮辐射和羽流辐射。根据有目标和无目标两种情况下图像特性的差异，可以判断图像中是否存在目标，从而为目标识别提供了关于目标和背景的先验知识，研究结果可用于海空背景下红外小目标的检测。

Statistical analysis for infrared image of small target in sea and sky background

A statistical analysis of features of infrared images of small targets and backgrounds is made according to the practical requirement for small target recognition under the complicated background of sea and sky. The analysis of the images in the wave band of 3~5 μm and 8~12 μm both with and without targets is made, including such features as the mean of gray value, standard deviation, and covariance, as well as the variance of local contrast, Signal-to-Clutter ratio and threshold with detecting distance. The histogram of infrared images is also analyzed. The results show that the missile′s radiance received varies linearly with the detecting distance, and when it reaches the distance about 8 200 m from the sensor， the missile′s envelop radiation and plume radiation can be distinguished from the infrared image. Based on the difference between the infrared image in both with and without target situations, it can be determined whether the target exists. This research provides the researchers with prior knowledge about small target and background on target recognition .The results can be applied to the IR detection of small targets in sea and sky background.