Spectral Conversion function

The Spectral Conversion function applies a matrix to a multiband image to affect the spectral values of the output. This can be used, for example, to convert a false color image to a pseudo color image.

The inputs for this function are the following:

The equation used to perform this conversion is:

Output Band_R = Weight_P * Band_C


False color versus pseudo color

A false color image is created by combining three available bands into a red, green, and blue (RGB) display in which the output spectral values each represent red, green, or blue. For example, you could convert a SPOT image that lacks a blue band into what will appear as a true color image by generating a blue band from the other available bands and using the red and green bands that are part of the SPOT image dataset.

A pseudo color image is created from a single-band image (grayscale) or a multiband image by applying a transformation to create colors where there are none. For example, a thermal image may be displayed as a pseudo color image using a continuous, three-color-toned color ramp to produce an image displaying three classifications of heat. A pseudo color image can be created from multispectral images by applying the Spectral Matrix process to determine color bands from other bands.

The following matrix can be used to convert a false color (near infrared, red, and green) image to a pseudo color (RGB) image:

0.1 0.9 0.0 
0.3 0.0 0.7 
0.1 0.1 0.8

Using the conversion equation and our false color to pseudo color matrix, the output bands would be the following:

The image below uses a SPOTView ORTHO Basic image, with four bands. The first three bands are displayed, creating an infrared image on the right side. Using the Spectral Conversion function with the matrix above, this image can be converted to a true-color image, as shown on the left side.

Spectral Conversion function example
Spectral Conversion function example

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