Manual

June 2004 Isis® Sonar User's Manual, Volume 2 88
Despeckle
(slider bar)
Removes “noise” from the image. Noise is defined as any pixel
that exceeds the median kernel value as defined by a median
kernel cell size and a sensitivity value. The median kernel cell
size can have values of 3, 5 or 7. Sensitivity is the number used
to determine how different the center pixel in the image region
must be before the pixel is replaced by the region's median
value. During despeckling, the image is examined in CellSize x
CellSize regions. The value in the center pixel is compared to the
median value for that region. If the difference between the center
value and the median value exceeds the value specified on the
Despeckle bar, the center pixel is replaced with the median
value. Otherwise, the center pixel keeps its original value. Every
pixel in the image is analyzed in this way.
Vignette
Lighting
(radio buttons)
Vignette lighting compensates for large variations of light (or lack
of it) in the background of the image. When vignetting is applied,
points furthest from the center of the image are darkest, and
points closest to the center are lightest.
Appendix E: Using the Target Utility