In order to reduce the spectral distortion existed in the fusion images generated by wavelet transform method

this paper developed a new fusion method called direct addition to process the low frequency information. The method directly added the original resized TM image that was not decomposed and the reconstruction images generated only with the high frequency parts of the decomposed SPOT image. The analysis of the spectral distortion and image entropy showed that the direct addition method was better than the general wavelet transform methods. Because the direct addition method does not need to decompose the multi-spectral images

its fusion speed was faster than the general wavelet transform methods. The spectral quality comparison of wavelet transform and IHS transform showed that wavelet transform is more suitable than IHS transform for the fusion of images with different spectral response ranges and for the fusion of images with little correlation. The spatial quality comparison showed that wavelet transform was excelled at the fusion of images contained medium scale or small scale texture characteristics.