National Instruments Image Acquisition Software - Manual (Page 43)

Appendix A StillColor
NI-IMAQ User Manual A-6 © National Instruments Corporation
StillColor RGB
RGB cameras output a color image using three lines. StillColor RGB will
acquire the three signals and construct a color image. The three lines are
connected to three channels on the PCI/PXI-1408. One frame is acquired
from each of the three channels, which represent the red, green, and blue
planes of the image. StillColor combines these frames to construct the color
image.
RGB Color Acquisition
The PCI/PXI-1408, in conjunction with NI-IMAQ, supports acquisition of
color images from an RGB camera.
The NI-IMAQ driver can acquire the three frames and rebuild the image
automatically. The output image can be a simple RGB color image or
one of many image representations supported by the driver. See the
Introduction to Color section later in this appendix for more information
on image representations.
For a StillColor RGB snap, connect the three camera channels—red, green,
and blue—to Video 1, Video 2, and Video 3, respectively, on the
PCI/PXI-1408 device. Specify a channel for the video synchronization
signal by selecting that channel as the sync source using the Operating
Mode tab in the IMAQ Configuration Utility. A typical RGB camera
includes the composite video synchronization signal in the green signal.
You can also use other synchronization sources, such as an external
composite video signal that can be connected to Video 0 or an external TTL
composite synchronization signal that can be connected to the CSYNCIN
pin of the DSUB connector. (See Chapter 4, Signal Connections, of your
hardware user manual for signal connection information.)
Introduction to Color
Color is the wavelength of the light we receive in our eye when we look at
an object. In theory, the color spectrum is infinite. Humans, however, can
see only a small portion of this spectrum—the portion that goes from the
red edge of infrared light (the longest wavelength) to the blue edge of
ultraviolet light (the shortest wavelength). This continuous spectrum is
called the visible spectrum, as shown in Figure A-3.
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