Pixel-The smallest single picture element with which an image is constructed. The light-sensitive elements in a CCD (chip) camera. Preroll-To start a videotape and let it roll for a few seconds before it is put in the playback or record mode so  that  the  electronic  system  has  time  to  stabilize. RGB-The  separate  red,  green,  and  blue  color (chrominance), or “C,” video signals. Slant  Track-Same  as  helical  scan. Time  Base  Corrector  (TBC)-An   electronic accessory to a videotape recorder that helps make playbacks  or  transfers  electronically  stable.  A  TBC helps to maintain picture stability even in dubbing-up operations. Video Cassette-A plastic container in which a videotape moves from a supply reel to a take-up reel. Used in all but the 1-inch VTRs. VTR-Videotape  recorder  or  recording.  Includes video  cassette  recorders. Y/C-The separate processing of the luminance (Y) and  chrominance  (C)  signals. VIDEOTAPE RECORDERS RECORDING SYSTEMS Analog  and  Digital  Systems Both analog and digital systems are used in naval imaging facilities. The analog system is easier to understand if you think of it in the same terms as a record and   a   phonograph.   Analog   systems   record   the continually fluctuating video signal that is created and processed by a video source (camera) on videotape. 13-5 Videotaping is similar to audiotape recording. The electronic  impulses  of  television  pictures  (video  signal) and sound (audio signal) are recorded on the videotape by magnetizing the iron oxide coating on the videotape. During playback, the recorded video and audio signals are  converted  again  by  the  television  set  into  television pictures and sounds. However, the amount of electronic information is many times greater for video than for audio  recording. There are many different systems of treating and recording  the  video  signals.  Videotape  recording systems can be divided roughly into three subsections: analog and digital; composite (Y/C), and component; and  tape  formats. In a true component system, the R, G, B channels are kept separate and treated as separate red, green, and blue video signals throughout the entire recording process. Each of the three signals remains separate even when laid down on the videotape. The component system requires three wires to transport a video signal. This means that all equipment used in the component system requires three wires to handle the video signal that  is  incompatible  with  the  NTSC  system. When the video is going to be televised, the signals of the Y/C and component systems must be combined into a single NTSC composite signal before it can be broadcast. During playback, the recorded information is retrieved as an identical, continually fluctuating signal from the videotape. Digital-video systems work on the same principle as compact disks (CD) used in your home stereo or office  computer.  Digital-video  systems  convert  the analog video signals by sampling (selecting parts of) the scanned image. It then translates the scanned image into millions of independent, fixed, values called pixels. A pixel is the smallest single picture element from which images are constructed. Each pixel has its own color (hue and saturation) and luminance values. These values are expressed as binary numbers (series of zeros and ones). The binary numbers are then stored on, and retrieved from, videotape or other storage mediums, such  as  large-capacity  disks. Composite (Y/C) and Component Composite (Y/C) and component all refer to the way the video signal is treated in the videotape recorder. A composite video signal means that the luminance information  (“Y”  signal),  chrominance  information (“C” signal), and the sync information are combined into a single signal (Y+C+sync). Standard television information is designed to operate with composite video signals.  Only  one  wire  is  required  to  transport  a composite video signal. This composite signal is usually called NTSC, because the electronic specifications for a  composite  video  signal  were  adopted  by  the  National Television Standards Committee. The  major  disadvantage  of  a  composite  signal  is  that slight  interference  exists  between  the  chrominace  and luminance information. This interference becomes more  noticeable  through  each  videotape  generation.