Infrared Image Enhancement Based on Adaptive Bilateral Filtering and Directional Gradient

To overcome the defects of existing infrared image enhancement methods, such as under-enhancement, over-enhancement, and low contrast, an infrared image enhancement method based on adaptive bilateral filtering and directional gradient is proposed. The bilateral filter was improved, and its weighting coefficient is now adaptive to smooth and detailed regions. The improved bilateral filter is used as the central surround function of Retinex to decompose the infrared image into a base layer and a detail layer. Using improved platform histogram equalization, the base layer image is enhanced, and a directional gradient operator is proposed to extract the gradient image of the detail layer image to perform nonlinear adaptive edge enhancement on the detail-layer image. Experimental results show that, compared with existing methods, the proposed method can improve the brightness and contrast of infrared images more effectively. In addition, the visual effect of enhanced images using this method is better.