1. Conventional “analog” TV
• Commercially available since late 1930’
• Picture formed by sweeping an electrical signal
ITMA 11 horizontally across the screen one line at a time.
Introduction to Video and Film
Krates Ng
Fall 2008
from www.maxim-ic.com
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Interlaced scanning
• TV uses interlaced
scanning
• Each picture, referred
to as a frame, is
divided into two
separate sub-pictures,
referred to as fields.
Two fields, odd and
even, make up a frame.
from www.maxim-ic.com
3 4
Progressive Scanning
• Used in delivering
computer signals.
• Picture is painted on
the screen by scanning
all of the horizontal
lines of the picture in
one pass from the top
to the bottom.
from www.maxim-ic.com
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2. Resolution Standard Video Resolution
• Computer visual signals use pixel resolution.
• Standardized computer display resolutions:
Name Width Height
QVGA 320 240
VGA 640 480
SVGA 800 600
XGA 1024 768
SXGA 1280 1024
WXGA 1366 768
UXGA 1600 1200
WUXGA 1920 1200
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3 major world TV systems
• TV uses lines • NTSC
– National Television Systems Committee
– e.g. 525 lines in NTSC, 625 lines in PAL
– Used in USA and Japan
• PAL
– Phase Alternating Line
– Used in UK and Asia
• SECAM
– Sequential Coleur Avec Memoire
• Many sub systems under each major system.
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Which country uses which? NTSC
• Interlaced into two fields
• 525 scan lines per frame ( 485 visible lines
max.).
• Ordinary TV has about 320 lines.
• Vertical frame rate: 29.97 frame/sec.
• Bandwidth 4.2MHz
• Used to use YIQ color model (now YUV)
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from wikipedia.org
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3. PAL Visible raster area
Vertical blanking period
• Interlaced into two fields
Horizontal blanking period
• 625 scan lines per frame (≈ 575 visible max.)
525 lines (NTSC)
• Vertical frame rate: 25 frame/sec.
625 lines (PAL)
About 480 visible
About 576 visible
• Bandwidth 5.5MHz Visible raster area
• Uses YUV color model
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NTSC and PAL YUV Color Model
• NTSC • YUV model defines a
– Less flicker color space in terms of
one luminance
– Poorer resolution
(brightness) and two
• PAL chrominance (color)
– Sharper resolution components.
– More flicker • Models human color
reception better than
RGB.
from wikipedia.org
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YUV from RGB YUV
• Y= 0.299R + 0.587G + 0.114B
Original U
• U= 0.492(B − Y)
= − 0.147R − 0.289G + 0.436B
• V= 0.877(R − Y) V
Y
= 0.615R − 0.515G − 0.100B
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4. Advantages of YUV Digital TV in HK
• Compatible with black & white analog TV • 31 Dec 2007: Digital Terrestrial Television
sets: Transmit Y and ignore U and V. (DTT)
• Can easily discard color information • Four major systems:
according to the available bandwidth since – ATSC (adv. Tv systems committee): US, .kr, .ca
humans are more sensitive to luminance. – DVB-T (digital video broadcasting – terrestrial): EU,
.sg, .au, .nz
– ISDB-T (integrated services digital broadcasting –
terrestrial): JP
– GB20600-2006: CN, HK
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What do you need to get DTTV? References
1. Check your coverage • www.digitaltv.gov.hk
2. Check your building • www.hkdtt.tv
3. Set-top box or iDTV • Coverage in HK:
– http://www.digitaltv.gov.hk/general/pdf/covera
ge.pdf
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Film to Video Transfer
Film
Squeezing 24
film frames into
• Progressive scanning 30 video frames
is achieved by
• Run as 24 frame/sec. (fps) repeating fields
• Film formats: in a 3:2
sequence (AKA
– http://www.widescreenmuseum.com/widescree 3:2 pulldown)
n/apertures.htm
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