where l is a correction factor ranging from 0 for very high
densities to 1 for very low densities. A value of 0.5 was
used in this study to produce enhanced vegetation image
as the study region has an intermediate vegetation density
(Figure 1b and 1f).
It is noted in this test that SAVI is really more sensitive
than NDVI in detecting vegetation in the low plant-covered
areas due largely to the increased data dynamic ranges of the
images (Table 1). The increased dynamic range is 85 when
the difference is rescaled between 0 and 255 to provide
output as unsigned 8-bit data. The increase in the range can
make the discrimination of vegetation from built-up land or
water easier. For example, the NDVI difference between
vegetation and built-up land in Quanzhou image is 0.61,
whereas the SAVI difference between them is 0.92 (Table 2).
A 0.31 or 50 percent contrast increase would greatly help in
the separation of these two classes.