Appendix B
StillColor
PCI/PXI-1408 and NI-IMAQ for Win95/NT
B-8
©
National Instruments Corporation
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Luminance, which is the brightness information in the video
picture. The luminance signal amplitude varies in proportion to the
brightness of the video signal and corresponds exactly to the
monochrome picture.
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Intensity, which is the brightness of a color and which is usually
expressed as light or dark. For example, orange and brown may
have the same hue and saturation; however, orange has a greater
intensity than brown.
Image Representations
Color images can be represented in several different formats. These
formats can contain all color information from the image or they can
consist of just one aspect of the color information, such as hue or
luminance. The following image representations can be produced using
NI-IMAQ and StillColor.
RGB
The most common image representation is 32-bit RGB format. In this
representation, the three 8-bit color planes—red, green and blue—are
packed into an array of 32-bit integers. This representation is useful for
displaying the image on your monitor. The 32-bit integer organized as:
where the high-order byte is not used and blue is the low-order byte.
The system also supports a 24-bit and a 16-bit representation of the
RGB image. The 24-bit representation is equivalent to the 32-bit
representation; however, there is no unused byte. For the 16-bit
representation, the image is packed into an array of 16-bit integers
where each 16-bit pixel contains red, green, and blue, encoded with
only five bits each. The most significant bit of the integer is always 0.
Color Planes
Each color plane can be returned individually. The red, green, or blue
plane is extracted from the RGB image and represented as an array of
8-bit integers.
0
RED
GREEN
BLUE