Research On Infrared Image Detail Enhancement Algorithm Based On Image Layering By Filter

Infrared images have the characteristics of high dynamic range,concentrated gray levels and low SNR.And if displayed directly will result in low contrast and loss of detail,so certain enhancement algorithm is needed to get good visual effect for infrared images.Traditional enhancement algorithm of dynamic range compression can effectively improve the image contrast,but the details of the image cannot be enhanced enough.So further research on detail enhancement besides traditional algorithms has gradually become the one of the hotspots of infrared image processing.The existing detail enhancement algorithms is mainly based on the theory of dividing the image into base layer and detail layer by a low-pass filter,then compress the high dynamic range of base layer and amplify the details in detail layer,finally combine the layers to get the processed image.Compared with the traditional enhancement methods,the existing detail enhancement algorithm can increasing the degrees of detail better,but it can also cause the problem of fuzzy the basic image texture,uneasy control of the gain parameter of details and noise amplification.According to the defect of the existing algorithms,this paper proposes an improved detail enhancement algorithm for infrared image based on layering method,considering of the guided image filter for strong edge and image gradient preservation,the guided image filter is selected as the layer filter.And in order to be applied easily to real-time infrared imaging processing system,the statistical characteristics of the image local variance is considered to adaptively choose the filter parameters.To avoid blurred the image texture for the base layer dynamic range compression,a linear window is used to estimate the invalid gray level in the histogram,and then modify the mapping curve to get better map result.For detail layer processing,the twice filtering and improved noise masking method is used to suppress the noise by analyzing the feature of detail image.Finally when combining the base layer and detail layer,the ratio of the two filter parameter is used to control detail layer gain.The experimental results show that the proposed algorithm can more accurately remove invalid gray levels of basic layer and keep the natural features of infrared images,as well as compress detail layer noise,effectively control the detail layer gain to avoid excessive enhancement distortion or insufficient enhancement,finally achieve satisfactory detail enhancement effect.