A straightforward data layout is used in these algorithms for all
platforms. The input image is an 
matrix of integers. We
assign tiles of the image as equally as possible among the processors.
If p is an even power of two, i.e. 
, for even d, the
processors will be arranged in a 
logical
grid. For future reference, we will denote the number of rows in this
logical grid as v and the number of columns as w. For odd d, we
assign the number of rows of the logical processor grid to be 
, and the number of columns
to be 
. Each processor
initially owns a tile of size 
. For
future reference, we assign 
and 
.
We assume that the p processors are labeled consecutively from 0
to p-1 and are assigned in row-major order to the logical processor
grid just described.
Our test images shown in Appendix A are divided into two
categories, artificial and real. The artificial images, given in
Figures 6 and 7, range in size from
to 
pixels. We use Landsat satellite
data to represent real images; Figure 8 is from band 5
of a South American scene, and Figure 9 is band 4 taken
from a view of New Orleans. Both of these images are 256 grey level,
pixel arrays from single bands of the Landsat
Thematic Mapper (TM) satellite data.