Triton Isis - Manual (Page 287)

June 2004 Isis® Sonar User's Manual, Volume 1
273
DC Offset
(slider bar)
Use this if you want to offset your signal voltage by an amount in
the range 5V, in increments of 0.01V, before you apply TVG.
This function appears in the “Custom” view of the TVG and
Balance dialog box (right panel of Figure 10-26). The advantage
of having this function in the TVG dialog box is that your voltage
signal won’t be unduly affected by sudden or extreme changes,
such as scrolling through imagery that changes from a rough to
smooth seafloor (or vice versa).
Balance
(check box)
When this box is checked, you can normalize the effects of your
TVG through these controls:
• Channel-to-channel: By calculating the average
darkness value of channels, this makes your channels
have the same darkness value. This is a useful setting to
use if one channel is lighter or darker than another.
• Pixel-to-pixel: By calculating the average value of a
single column of pixels, this makes the pixels have the
same value. Effectively this levels the signal across track.
If your imagery contains striping, applying a pixel-to-pixel
normalization will help eliminate the striping.
• Darkness: This slider bar controls the degree of light or
dark that you want to be applied to your imagery. The left-
most point on the bar applies maximum brightness (0%,
or white) to your imagery; the right-most position gives
maximum darkness (100%, or black).
• Decay Rate: This controls the speed at which your TVG
settings are applied across your imagery. As this value
increases, more pings are considered when computing an
average. The left-most position on the slider bar is 0,
meaning no decay rate is applied; the right-most position
is 50, which is the maximum amount of decay rate that
can be applied.
The What’s this? button summarizes the foregoing. The default
for Balance is an unchecked box (no TVG balancing to be done).
Chapter 10: Using the Window Menu