针对基于小波变换的图象融合中存在的光谱扭曲问题，提出了一种直接相加的小波变换低频信息处理方法，即将未分解的 TM放大图象与小波分解后的 SPOT图象的高频部分重构得到的图象通过直接相加来生成融合图象，这种方法得到的融合图象，其光谱扭曲值和信息量两个指标均优于常规的小波融合方法.由小波变换与 IHS变换的光谱质量比较表明，小波变换比 IHS变换更适合于波谱响应范围不同、相关性弱的图象间的融合 ;另外，空间质量比较还表明，小波变换在融合中、小尺度的纹理特征方面具有优势.

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.