Image 1.  This is principal component 1 (PC-1) of the three visible bands.  It looks pretty much the same as any of the three bands viewed individually in grayscale.

Image 2.  This is principal component 1 (PC-1) of the two middle-infrared bands.  It looks pretty much the same as either of the bands viewed individually in grayscale.

Image 3.  This is the original Thematic Mapper Band 4 (near-infrared).  Vegetation is light-toned because of its high response in this region of the spectrum.

Image 4.  This is the soil brightness index (SBI).  As you can see, the lightest-toned features are the open urban areas and the bare agricultural fields.

Image 5.  This is the green vegetation index (GVI).  As you can see, the forests are much lighter than the surrounding features.  This image is almost like a negative of the soil brightness index shown above (Image 4).

Image 6.  This is the merged image with the five layers of spectrally enhanced data.  It is displayed here in true color with layers 2,4,1 (RGB).  This means that TM Band 4 (near-IR) is in the red color gun, the soil brightness index (SBI) is in the green, and PC-1 of the visible bands is in the blue.  I think that this image is interesting because it shows how the various types of features all have quite distinguishable signatures.  Notice especially how well the Country Club, the industrial district, and the water features stand out.