Abstract: An infrared image processing solution is proposed. It uses bithreshold method to segment image and enhance the image with segmentation gray scale transform method．For a specific image，two thresholds are selected manually to cut the image into three parts (target area，transition area and background area).Based on the characteristic of each part，different gray scale transforms are designed to carry out image linear enhancement to get the best visual effect for the interested area. The satisfactory result is achieved with the experiment on 16 bit infrared images. The experiment shows that the algorithm is flexible and convenient. It can increase the contrast and decrease the noise while suppressing the background.