Multispectral Image Sharpening Using Wavelet Transform Techniques and Spatial Correlation of Edges

摘要

Several reported image fusion or sharpening techniques are based on the discrete wavelet transform (DWT). The technique described here uses a pixel-based maximum selection rule to combine respective transform ocefficients of lower spatial resolution enar-infrardd (NIR) and higher spatial resolution panchromatic (pan) imagery to produce a shaprpened NIR image. Sharpening assumes a radiometric correlation between the spectral band images. However, there can be poor correlation, including edge contrast reversals (e.g., at soil-vegetation boundaries), between the fused images and, consequently, degraded performance. To improve sharpening, a local area-based correlation technique originally reported for edge comparison with image pyramid fusion is modified for application with the DWT process. Futher improvements are obtained by using reducdant, shift-invariant implementation of the DWT. Example images demonstrate the improvements in NIR image sharpening with higher resolution pan imagery.