Satellite Image Fusion
Several methods are there for merging satellite images. In satellite imagery we can have two types of images
- Panchromatic images - An image collected in the broad visual wavelength range but rendered in black and white.
- Multispectral images - Images optically acquired in more than one spectral or wavelength interval. Each individual image is usually of the same physical area and scale but of a different spectral band.
The SPOT PAN satellite provides high resolution (10m pixel) panchromatic data. While the LANDSAT TM satellite provides low resolution (30m pixel) multispectral images. Image fusion attempts to merge these images and produce a single high resolution multispectral image.
The standard merging methods of image fusion are based on Red-Green-Blue (RGB) to Intensity-Hue-Saturation (IHS) transformation. The usual steps involved in satellite image fusion are as follows:
- Resize the low resolution multispectral images to the same size as the panchromatic image.
- Transform the R,G and B bands of the multispectral image into IHS components.
- Modify the panchromatic image with respect to the multispectral image. This is usually performed by histogram matching of the panchromatic image with Intensity component of the multispectral images as reference.
- Replace the intensity component by the panchromatic image and perform inverse transformation to obtain a high resolution multispectral image.
An explanation of how to do Pan-sharpening in Photoshop.
Read more about this topic: Image Fusion
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