Video is created by capturing sequential still images called frames rapidly enough to create the illusion of motion when played back. Frames are made up of pixels which are tiny light-sensitive dots that capture color. Images are drawn by scanning across pixels from left to right and top to bottom using either progressive or interlaced scanning. Higher frame rates and resolutions provide smoother motion and more detail but require more storage space. Playing back video at the same rate it was captured maintains normal speed, while changing the rate can create slow or fast motion effects.

1. EMC 3130
Lecture One
Digital Video – How Does This Work?
Pixels to Scenes
Edward Bowen

2. How Television Works
http://www.youtube.com/watch?v=UivqdpliyA0

3. How Digital Cameras Work
http://www.youtube.com/watch?v=VP__-EKrkbk

4. Digital Camera Deconstructed
http://videos.howstuffworks.com/science-channel/37727-
deconstructed-digital-cameras-video.htm

6. What is Video?
Video is electronically captured and
disseminated sequential still images
(frames) in rapid enough succession to
create the illusion of motion, stored
either analog or digitally, and
synchronized with sound.

7. What is Video?
Video is electronically captured and
disseminated sequential still images
(frames) in rapid enough succession to
create the illusion of motion, stored
either analog or digitally, and
synchronized with sound.

8. Analog
• A wave is recorded or used in its original form
• Light or sound are converted to a fluctuating electrical wave that
is directly recorded, usually to a magnetic tape
medium, mirroring the original stimulus.
• It produces an electrical copy of an original stimulus.
• Analog signal fluctuates exactly like the original stimulus.
• Analog signal is continuous.

9. Digital
• The analog wave is sampled at some interval, and then turned
into numbers that are stored in the digital device
• Light and sound are recorded not as an identical copy of the
original stimulus, but as discrete on-and-off pulses, zeros and
ones, binary digits.
• It is a representation rather than a copy.
• Discontinuous. Signal is sampled.
• Advantage: Resists data distortion and error in duplication. No
generational loss.
• Advantage: Allows for manipulation of sound and image.

10. Digital
http://youtu.be/kR7227_ndqQ

11. Digital
http://www.dailymotion.com/video/xkgkkv_dr-michio-
kaku-on-the-conversion-from-analog-to-digital_tech

12. Digital

13. Digital
• Sampling/Quantizing
• Compression and Codecs (Compression-
Decompression, Encoding-Decoding)
• Downloading and Streaming
Advantages
• Lossless Copying
• Compression
• Manipulation

14. Basic Image Formation
Compression
• CODEC – a device or program for encoding and/or
decoding digital information
(DivX, Xvid, H.264, WMV, etc.)
• Container of Wrapper Format
(AVI, FLV, QuickTIme, MPEG, MP4, etc.)
• Lossy vs. Lossless
• Lossy - Permanently removes information, such as
repeated pixels.
• Lossless - Compresses and decompressed without
loss of information.
• Compression Ratio - the higher the ratio, the smaller
the file; the lower the ratio, the higher the quality.

15. Digital Compression
http://vimeo.com/1172256

16. Digital Compression
http://youtu.be/nH3nmBEPIHY

17. What is Video?
Video is electronically captured and
disseminated sequential still images
(frames) in rapid enough succession to
create the illusion of motion, stored
either analog or digitally, and
synchronized with sound.

18. Sequential Still Images (Frames)
• The individual pictures that make up
video are “frames.”

19. Sequential Still Images (Frames)
• The individual pictures that make up
video are “frames.”
• The frames are comprised of millions of
electrically excitable “pixels” (picture
elements)

20. Pixels
• The individual pictures that make up
video are “frames.”
• The frames are comprised of millions of
electrically excitable “pixels” (picture
elements)
• For color, each pixel is comprised of
three parts (red, blue, green)

21. Pixels
http://youtu.be/ugV6cLgwomo

22. Pixels
http://youtu.be/DCTRk5a0aJg

23. Pixels
http://vimeo.com/18881890

24. Sequential Still Images (Frames)
• The individual pictures that make up
video are “frames.”
• The frames are comprised of millions of
electrically excitable “pixels” (picture
elements)
• For color, each pixel is comprised of
three dots (red, blue, green)
• Individual images are drawn by
scanning along these pixels from left to
right, top to bottom.

26. Scanning
High speed video showing the fluorescent screen of
CRT television being scanned by electron gun.
http://youtu.be/zVS6QewZsi4

27. Scanning
http://www.dailymotion.com/video/xjoyzr_cbs-entertainment-productions-
london-films-persistence-of-vision-mgm-television_shortfilms

28. Scanning
• Interlaced Scanning - Two fields
comprise a frame.

29. Scanning
• Interlaced Scanning
Misaligned fields

30. Scanning
• Progressive Scanning (Computers and
Most Digital Video)
• Refresh Rate: Frames scanned per
second.

31. Scanning
• Progressive v Interlaced Scanning

32. Scanning
• Progressive v Interlaced Scanning

33. Scanning
• Progressive v Interlaced Scanning
http://youtu.be/gbtBP8QxGg8

34. Scanning
http://video.answers.com/how-ntsc-interlaced-video-works-291907666

35. Resolution
Standard Television
• 480i (480 horizontal lines visible, interlaced;
30 frames per second)

36. Resolution
Digital Television (DTV)
• Higher Picture Resolution
• Truer Color
• Wider Contrast Ratio
Four prominent systems:
• 480p (progressive, 480 visible lines, 60 frames per
second)
• 720p (progressive, 720 visible lines, 60 frames per
second, High Definition Television [HDTV]
• 1080i (interlaced, 60 fields/30 frames per
second, High Definition Television [HDTV]
• 1080p (progressive, 60 frames per second, [HDTV]

37. Resolution

38. Resolution
720p 1080p

39. Resolution

42. Resolution
Additional Systems
24p - 1080 lines of resolution, 24 frames per second.
• For use in conjunction with motion picture film
• Or to create a “film look.”

43. Resolution
http://vimeo.com/3388256

44. Resolution
Additional Systems
2K, 4K and 5K – 2000, 4000 and 5000 lines of
resolution
• For use in theatrical screening and 35mm scanning

45. Resolution
Resolution – The Detail an Image Contains
• Horizontal lines of pixels times vertical lines of pixels
• VHS - 200 by 480
• Mini-DV - 720 by 480
• CineAlta 24p - 1920 by 1080
• 35mm film - 4000 by 3000
• Red One - 4520 by 2540

46. Resolution
Resolution – The Detail an Image Contains
• Horizontal lines of pixels times vertical lines of pixels
Analog and early digital
• 300×480 : VHS,
• 500×480 : Analog broadcast

47. Resolution
Resolution – The Detail an Image Contains
• Horizontal lines of pixels times vertical lines of pixels
Digital
• 720×480 :DVD, miniDV
• 1280×720 (-1MP) : HD DVD, Blu-ray, HDV (miniDV)
• 1440×1080 (1.5 MP) : HDV (miniDV)
• 1920×1080 (2MP) : HDV (miniDV), AVCHD, HD DVD, Blu-ray,
• 2048×1080 : 2K Digital Cinema
• 4096×2160 : 4K Digital Cinema
• Sequences from newer films are scanned at 2,000, 4,000, or
even 8,000 columns, called 2K, 4K, and 8K, for quality visual-
effects editing on computers

48. What is Video?
Video is electronically captured and
disseminated sequential still images
(frames) in rapid enough succession to
create the illusion of motion, stored
either analog or digitally, and
synchronized with sound.

49. Frame Rates
(frames per second)
Shutter Speed
(fraction of a second)

50. Frame Rates
The number of frames captured in a
second
(frames per second)
Shutter Speed -
The time light is allowed to strike the
image sensor to create a single
image.
(fraction of a second)

51. Frame Rates
(frames per second)
Higher frame capture and playback rates result in more
information and higher picture quality with increased
sharpness, less stutter and flicker, and less motion blur.

53. Frame Rates
(frames per second)
Impact on Image Quality and Smoothness of Motion
http://youtu.be/e54Q1KXRmX0

54. Frame Rates
(frames per second)
Impact on Image Quality and Smoothness of Motion
http://youtu.be/-nU2_ERC_oE

55. Frame Rates
(frames per second)
Impact on Image Quality and Smoothness of Motion
http://youtu.be/3xsSSsVqSA0

56. Frame Rates
(frames per second)
Impact on Video Speed
When video is played back at the same frame rate as it
was captured, motion appears normal.
When video capture speed is faster than it is played
back, slow motion results, since the video is playing
back at a SLOWER speed than it was captured.
30fps Capture - 30fps Playback: Normal Motion
60fps Capture - 60fps Playback: Normal Motion
60fps Capture - 30fps Playback: Slow Motion
300fps Capture - 30fps Playback: Slow Motion

57. Frame Rates
(frames per second)
Impact on Video Speed
When video is played back at the same frame rate as it
was captured, motion appears normal.
When video capture speed is slower than it is played
back, fast motion results, since the video is playing back
at a FASTER speed than it was captured.
30fps Capture - 30fps Playback: Normal Motion
60fps Capture - 60fps Playback: Normal Motion
30fps Capture - 60fps Playback: Fast Motion
3fps Capture - 30fps Playback: Fast Motion

58. Frame Rates
(frames per second)
Impact on Video Speed
When video is played back at the same frame rate as it
was captured, motion appears normal.
When video playback speed is altered in post
production to a slower frame rate than it was
captured, slow motion results, since the video is playing
back at a SLOWER speed than it was captured.
30fps Capture - 30fps Playback: Normal Motion
60fps Capture - 60fps Playback: Normal Motion
60fps Capture -30fps (or 50%) Playback: Slow Motion
60fps Capture - 6fps (10%) Playback: Slow Motion

59. Frame Rates
(frames per second)
Impact on Video Speed
When video is played back at the same frame rate as it was
captured, motion appears normal.
When video playback speed is altered in post production to a faster
frame rate than it was captured, fast motion results, since the video
is playing back at a FASTER speed than it was captured.
30fps Capture - 30fps Playback: Normal Motion
60fps Capture -60fps Playback: Normal Motion
60fps Capture -120fps (or 200%) Playback: Fast Motion
60fps Capture - 600fps (1000%) Playback: FAST Motion

60. Frame Rates
(frames per second)
Impact on Image Speed
http://vimeo.com/11648907

61. Frame Rates
(frames per second)
Impact on Image Speed
http://youtu.be/kgdyBvHdNKY

65. Shutter Speed
(fraction of a second)
Generally, shutter speed must be at least half of the
frame rate. At 30 frames per second, the shutter speed
will be approximately 1/60th of a second.
It can be faster is the camera allows.
A higher frame rate requires a faster shutter speed.
Shutter speed can be increased independent of the
frame rate.
A faster the shutter speed results in diminished blur
A slower shutter speed results in added blur.

67. Shutter Speed
(fraction of a second)
Impact on Motion Blur

68. Shutter Speed
(fraction of a second)
Impact on Motion Blur

69. Shutter Speed
(fraction of a second)
Impact on Motion Blur

70. Shutter Speed
(fraction of a second)
Impact on Motion Blur

71. Shutter Speed
(fraction of a second)
Impact on Motion Blur

73. Shutter Speed
(fraction of a second)
Impact on Motion Blur
http://vimeo.com/18873243

74. Shutter Speed
(fraction of a second)
Impact on Motion Blur
http://youtu.be/gFjbVZJ275k

75. Shutter Speed
(fraction of a second)
Impact on Motion Blur
http://vimeo.com/20310729

77. What is Video?
Video is electronically captured and
disseminated sequential still images
(frames) in rapid enough succession to
create the illusion of motion, stored
either analog or digitally, and
synchronized with sound.

78. The Illusion of Motion
• Persistence of Vision, Beta Movement, Phi Phenomenon
http://www.youtube.com/watch?v=3veFqnnob0A

79. The Illusion of Motion
• Persistence of Vision, Beta Movement, Phi Phenomenon

80. The Illusion of Motion
• Flicker Fusion and Frequency - the
flickering of light rapidly enough to
merge or fuse the images
• Apparent motion - Creating the illusion
of motion

81. Basic Image Formation
• Scanning
• Fields / Frames
• Flicker Frequency: Flashes per second
• Apparent motion
• Frames per second
http://dsc.discovery.com/videos/assignment-discovery-
shorts-tv-tube-and-the-flicker-frequency.html

82. Reality
http://youtu.be/6jzNw4_2YGQ

83. Basic Image Formation
Recording Media
• Film Stock
• Analog Video Cassette tape
• Digital Video Cassette tape
• DVD discs
• Digital Hard Drives
• Digital Memory Cards

84. NTSC
National Television System Committee
• http://www.ehow.com/video_4751914_
what-ntsc-video.html
• http://www.ehow.com/video_4751915_
what-difference-between-ntsc-pal.html

85. NTSC
National Television System Committee

86. NTSC
National Television System Committee