1 October 2003
c. Moving the NIR band into the green gun and adding band 5 to the red gun changes the
vegetation to green.
Figure 2-32. Three band combinations of Landsat imagery of 3/2/1, 4/3/2, and 5/4/3 in the
RGB. Images developed for Prospect (2002 and 2003).
k. Interpreting the Image. When interpreting the brightness of a gray scale image
(Figure 2-33), the brightness simply represents the amount of reflectance. For bright pix-
els the reflectance is high, while dark pixels represent areas of low reflectance. By exam-
ple, in a gray scale display of Landsat 7 band 4, the brightest pixels represent areas where
there is a high reflectance in the wavelength range of 0.76 to 0.90 m. This can be inter-
preted to indicate the presence of healthy vegetation (lawns and golf courses).
(1) A color composite can be somewhat difficult to interpret owing to the mixing of
color. Similar to gray scale, the bright regions have high reflectance, and dark areas have
low reflectance. The interpretation becomes more difficult when we combine different
bands of data to produce what is known as false-color composites (Figure 2-33).
(2) White and black are the end members of the band color mixing. White pixels in
a color composite represent areas where reflectance is high in all three of the bands dis-
played. White is produced when 100% or each color (red, green, and blue) are mixed in
equal proportions. Black pixels are areas where there is an absence of color due to the
low DN or reflectance. The remaining color variations represent the mixing of three band
DNs. A magenta pixel is one that contains equal portions of blue and red, while lacking
green. Yellow pixels are those that are high in reflectance for the bands in the green and
red planes. (Go to Appendix C for a paper model of the color cube/space.)