Spectral Band Usage
Further information: False-color.For different purposes, different combinations of spectral bands can be used. They are usually represented with red, green, and blue channels. Mapping of bands to colors depends on the purpose of the image and the personal preferences of the analysts. Thermal infrared is often omitted from consideration due to poor spatial resolution, except for special purposes.
- True-color uses only red, green, and blue channels, mapped to their respective colors. As a plain color photograph, it is good for analyzing man-made objects, and is easy to understand for beginner analysts.
- Green-red-infrared, where the blue channel is replaced with near infrared, is used for vegetation, which is highly reflective in near IR; it then shows as blue. This combination is often used for detection of vegetation and camouflage.
- Blue-NIR-MIR, where the blue channel uses visible blue, green uses NIR (so vegetation stays green), and MIR is shown as red. Such images allow seeing the water depth, vegetation coverage, soil moisture content, and presence of fires, all in a single image.
Many other combinations are in use. NIR is often shown as red, making vegetation-covered areas appear red.
Read more about this topic: Multispectral Image
Famous quotes containing the words spectral, band and/or usage:
“How does one kill fear, I wonder? How do you shoot a spectre through the heart, slash off its spectral head, take it by its spectral throat?”
—Joseph Conrad (1857–1924)
“What passes for identity in America is a series of myths about one’s heroic ancestors. It’s astounding to me, for example, that so many people really seem to believe that the country was founded by a band of heroes who wanted to be free. That happens not to be true. What happened was that some people left Europe because they couldn’t stay there any longer and had to go someplace else to make it. They were hungry, they were poor, they were convicts.”
—James Baldwin (1924–1987)
“I am using it [the word ‘perceive’] here in such a way that to say of an object that it is perceived does not entail saying that it exists in any sense at all. And this is a perfectly correct and familiar usage of the word.”
—A.J. (Alfred Jules)