Band Correlation

In most images the radiation that you receive in one wavelength is strongly correlated to the radition amount in most other bands. Bright is bright across the spectrum, as is dark. We see color or spectral differentiation in IR when radiation varies from the correlation line.

Here are some band correlations for the Virginia scene. This shows how, for each pixel, the radiance in one band compares to the radiance in others.

- - - - - - -x = B1, y = B2 - - - - - - - - - - -x = B5, y = B3 - - - - - - - - - - -x = B7, y = B4 - - - - - - - - - - -

all bands compared for a different place and time
image from a tutorial http://www.sbg.ac.at/geo/idrisi/wwwtutor/improc4b.htm

Band correlation produces images without much contrast. To eliminate the "paisley" colored images, we remove the correlation in Hue-Saturation-Intensity space.

From the examples folder in ERMapper, here is a RGB_321 (left) and RGB to HSI transformation with the color Saturation stretched to enhance color. The RGB to HSI equation is built into the eqn editor.