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Chapter 5
Configuration Utility
PCI/PXI-1408 and NI-IMAQ for Win95/NT
5-14
©
National Instruments Corporation
before the active video part of each line. Figure 5-5 shows the
correct position of Blank Start and Blank Stop.
–
X Shift—The X Shift parameter defines the number of pixels
before the X value of the acquisition window, where the
physical acquisition of the picture must start in order to
acquire the information needed by the StillColor algorithm.
The acquisition of the picture should start just before the
beginning of the color burst, as shown in Figure 5-5.
–
Post Gain—Post Gain rescales the picture after StillColor
processing so the white level appears white. You should not
modify the default value of 0.79.
–
Hue Offset Angle—When the selected Image Representation
is Hue 8-bit (or Hue 16-bit), the hue value of a pixel is an angle
where the value 0 corresponds to an angle of 0° and the value
255 (or 32,767 in Hue 16-bit) corresponds to 360°. The
discontinuity point (0 modulo 360) corresponds, by default, to
the color red. You can move this point to another hue value by
adding or subtracting an offset angle. The Hue Offset Angle is
expressed in degrees.
–
Clean Chroma (NTSC only)—This parameter enables or
disables the bandpass filter that cleans the chroma information
before final demodulation. You can use this filter if the camera
delivers a poor quality signal that results in vertical color bars
in the image, especially for highly saturated colors.
–
Setup Correction (NTSC only)—In NTSC, the black level of
the image is not aligned with the blanking level. The black
level is set up as 7.5% of the white level (7.5 IRE). To correct
for this setup after StillColor decoding, enable the Setup
Correction control. This control has no effect in PAL.
–
Setup Value (NTSC only)—This parameter is the setup value
to be corrected when Setup Correction is enabled. The default
value is 7.5% of the white level (7.5 IRE).
–
Tint (NTSC only)—In NTSC, inaccuracies in the coding,
transmission, or decoding part of the system can cause tint
errors. You can use Tint to correct for eventual tint inaccuracy
in the resulting image. Tint corresponds to a rotation of the
UV plane and is measured in degrees. This correction is not
needed for PAL.