Steerable Wavelet based fusion model for high-resolution remotely sensed image enhancement

High resolution image shows more detail information in Panchromatic(PAN) band and more spectral information in multi-spectral(MS) band. This paper aims at developing a new Steerable Wavelet Transform-Intensity Hue Saturation(STWT-IHS) fusion model considering the texture detail information of different direction of PAN band. The IHS transform of the multi-spectral image firstly gives the Intensity, Hue and Saturation bands. Thereafter, the PAN band and Intensity band were decomposed into different scales including direct-based detail scales. Then, the fused Intensity band is obtained by reconstruction with high frequency components of PAN band and low frequency components of Intensity image and IHS inverse transform generates the final fused MS image. After presenting STWT principle, the fusion technique scheme is advanced based STWT and IHS theory. PAN band and MS band1,2,3 of QUICKBIRD are used to access the quality of the fusion model. After selecting appropriate decomposition level for the model, the fusion scheme gives fused image, which is compared with generally used fusion algorithms (IHS, Mallat and SWT). The objectives of image fusion include enhancing the visibility of the image and improving the spatial resolution and the spectral information of the original image. For assessing quality of an image after fusion, information entropy and standard deviation are applied to assess spatial details of the fused images and correlation coefficient, bias index and warping degree for measuring distortion between the original image and fused image in terms of spectral information. For all the tested fusion algorithms, better result is obtained when STWT-IHS is used.