What Exactly is Television?  A process of transmitting images through a signal from one place or another

How Motion Pictures Work  Motion Pictures/Movies  the process of projecting moving images to a wall or screen  Like TV, based on principles of persistence of vision and phi phenomenon  The illusion of motion is created by a series of frames presented sequentially  Film  originally 16 fps (frames per second), but standardized as 24 fps

How Television Differs from Motion Pictures  Not one standard international frame rate  Frame rates range from fps  U.S. – National Television Standards Committee (NTSC): 30 fps  Europe – PAL/SECAM: 25 fps  Digital Switchover: ATSC/DVB  Frames are not complete, but are composed of dots that are displayed/scanned horizontally.  Interleaved lines: fields—together make up a frame

What the Picture Tube Does  A projected (scanned) beam is made up of electrons that produced light when they strike the phosphorous coating on the inside of the glass inside the tube  Electrons respond to a magnetic charge, so electromagnets are used to control the aim of the beam in a very precise manner.  Gausing  TV picture tube images are made up of dots  Raster – the entire 280 X 525 field of dots  4 x 3: aspect ratio

What is RGB Chroma?  Three scanning beams activate three basic colors of a prism: RGB (Red, Green, Blue) Chroma.  Together the colors of light create a white beam

The Role of Color Bars  Color Bars: The basic calibration and reference signal used in color television developed by NTSC.  They permit adjustment of color intensity, tine, and black level (brightness and contrast) on a monitor.

How a Television Camera Works  Early cameras were quite large because the imaging device was similar to a picture tube  Eventually, this expensive, hot, and heavy tube was replaced by a charge coupled device (CCD)

How a Television Picture Gets to You (Transmission)  In land-based trans- mission methods, radio waves make it possible to the signal from the studio to your home.  Rise of use led to the digital conversion we discussed during the webquest.  In terms of satellite, there are 2 major systems: Traditional  Microwave-based frequencies DSS  higher frequency  HDTV  more resolution  Digital Television The digital channel carries a megabit- per-second stream of digital data

Transmission (cont’d): Digital, cont’d  The reason that broadcasters can create sub-channels is because digital TV standards allow several different formats. Broadcasters can choose between three formats:  480i - The picture is 704x480 pixels, sent at 60 interlaced frames per second (30 complete frames per second).  480p - The picture is 704x480 pixels, sent at 60 complete frames per second.  720p - The picture is 1280x720 pixels, sent at 60 complete frames per second.  1080i - The picture is 1920x1080 pixels, sent at 60 interlaced frames per second (30 complete frames per second).  1080p - The picture is 1920x1080 pixels, sent at 60 complete frames per second.  (The "p" and "i" designations stand for "progressive" and "interlaced." In a progressive format, the full picture updates every 60th of a second. In an interlaced format, half of the picture updates every 60th of a second.)  The 480p and 480i formats are called the SD (standard definition), while the 720p, 1080i and 1080p formats are HD (high definition) formats.

Digital Television (cont’d)  The idea of sending multiple programs within the Mbps stream is unique to digital TV and is made possible by the digital compression system being used.  To compress the image for transmission, broadcasters use MPEG-2 compression  MPEG-2 allows you to pick both the screen size and bit rate when encoding the show.  A broadcaster can choose a variety of bit rates within any of the three resolutions.

Computer Video vs. Television Video  Computer screens have many times more dots  They do not interlace 2 fields (not needed with flicker)  Computer screen frame-rate can vary from 60fps to 120 fps

Complete the Chart TelevisionMotion PicturesComputers Purpose (original) # Frames Composition Aspect Ratio

How Videotape Works  Videotape was a plastic-covered magnetic tape that is coated with a layer of microscopic metal particles. These particles were capable of holding a magnetic charge.  The VHS format came into prominence.

Videotape (cont’d)  In the early 1990s, a camcorder was invented that combined the aspects and features of a VCR and a camera.  The recording surface of a VCR is called a head.  Two types of recording processes: Composite Component  Generations: copies of an original  Footage: first generation tape Analog Technology

Digital

Move over analog….  Digital Media  CD-ROMS  CD-RW  DVD  BLU-RAY  However, that is not necessarily the direction TV/video production is heading now

So how do we record now?  Now, we record directly into the camera’s internal memory OR use memory cards  SD Card  Secure Digital Memory Card  SDHC Card  High Capacity Class 2: minimum sustained DTS of 2MB/sec Class 4: minimum sustained DTS of 4MB/sec Class 6: minimum sustained DTS of 6MB/sec Class 10: minimum sustained DTS of 10MB/sec  SD/SDHC Cards are examples of flash memory:   Then we save it onto a Hard Drive

Compression Tsw

Review  Answer Questions #1-14  Quiz Time!: ○ History of Television ○ How the Technology Works ○ Webquest ○ This packet  Next week: Cameras & Composition