Page 281 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

270 CHAPTER 10 Video
1.25 MHz
1.25 MHz
Luma carrier
Chroma carrier
Audio carrier
Luminance
3.579545 MHz
Chromas
Luma carrier
Chroma carrier
Audio carrier
4.5 MHz
Total: 6 MHz
Luminance
4.43361875 MHz 6 MHz
FIGURE 10.27
Total: 8 MHz
NTSC (top) and PAL (bottom) composite video signals.
images onto the screen in succession at a nominal rate. These images are also called frames (with the frame rate still reflected in fps), but a digital picture has a much deeper ability for embedding information and manipulating the image. The electron stream of the CRT projected pixels of light onto a fluorescent screen (i.e., the pixel was projected wherever the electron beam landed on the screen and, hence, could move around the screen), but the new digital pixels were fixed upon the screen in individual elements/locations.
Frames of an orthogonal raster bitmapped image (i.e., a raster of pixels), as with analog video frames, are measured as width versus height (W3H). The basic image is also made up of pixels, the arrangement of which determines the frame size/resolution. However, in digital video, pixels only have one characteristic and that is color. The color is represented by a fixed number of bits (e.g., 24-bit color). The color bit count is termed “color depth” (CD) with the depth of color varied by the number of bits (e.g., 8-bit color would have eight color balance intervals between white and
Chromas
250 kHz Guard band 250 kHz Guard band