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195 Cards in this Set
- Front
- Back
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What is the speed of light? |
3*10^8 |
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What speed do all electromagnetic waves travel at? |
The Speed of Light (3*10^8) |
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What is the equation for wave speed? |
c=f*lambda |
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What is Luminance? |
Light Strength perceived by the human eye |
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What is Radiance? |
Total Energy Emitted |
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What is the wavelength range of visible light? |
400-700 nanometers |
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Short visible light wavelengths produce what colour light? |
Blue |
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Long visible light wavelengths produce what colour light? |
Red |
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In the retina, what do the Rods do? |
Perceive Black and White |
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In the retina, what do the cones do? |
Perceive Colour |
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How many Rods are there in the retina? |
120 million |
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How any cones are there in the retina? |
6 to 7 million |
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Where are the Rods located in the Retina? |
The peripheral area
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Where are the cones located in the retina? |
The central area |
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How many electromagnetic radiation bands are the cones in the retina sensitive to? |
3 |
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What is an active colour source? |
Something that emits different wavelengths of light to produce different colours |
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What is a passive colour source? |
Something that absorbs and reflects wavelengths of light |
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What colours do active displays use? |
RGB |
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What colours do passive displays use? |
Cyan, Magenta, Yellow |
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What is the colour gamut? |
The range of colours that can be produced by a particular display |
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What is the value of red sensitivity in our eyes? |
0.299 |
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What is the value of green sensitivity in our eyes? |
0.587 |
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What is the value of blue sensitivity in our eyes? |
0.114 |
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What does HLS stand for? |
Hue (pure dominant colour), Lightness, Saturation (dilution with white) |
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Define Resolution |
The number of pixels or samples in an image |
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What is the resolution of a digital compact camera? |
1-16 megapixels |
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What is the resolution of a wide screen TV? |
1024 x 576 (16:9) |
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What is the resolution of a HDTV? |
1080i or 720p |
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How many bits are used in a true colour pixel? |
24 bits (3 * 8 bit values for RGB ranging from 0 to 255) |
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What does GIF stand for? |
Graphics Interchange Format |
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What are the names of the two GIF formats? |
GIF87A and GIF89A |
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Does GIF use True Colour or Palette Colour? |
Palette |
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How many colours is GIF limited to? |
256 |
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What is the name of the compression that GIF uses? |
LZW (Lempel-Ziv-Welch) |
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Is LZW compression lossy or lossless? |
Lossless |
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What does GIF support? |
Transparency |
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What is the first part of a GIF file? |
Signature |
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What is the second part of a GIF file? |
Screen Descriptor |
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What is the third (and optional) part of a GIF file? |
Global Colour Map |
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What is required for the Global Colour Map to be left out of a GIF file? |
For each frame in the picture, a local colour map needs to be given |
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What is the first part of EACH FRAME in a GIF file? |
Image Descriptor |
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What is the second (and sometimes optional) part of EACH FRAME in a GIF file? |
Local Colour Map |
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What is the third part of EACH FRAME in a GIF file? |
Image Data |
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What is the last part of a GIF file? |
File Terminator |
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What do the first two bytes in the Screen Descriptor of a GIF file describe? |
Screen Width |
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What do the third and fourth bytes in the Screen Descriptor of a GIF file describe? |
Screen Height |
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What four things does the 5th byte of the Screen Descriptor of a GIF file describe? |
1) Whether the global colour map follows 2) Bits per pixel in the image 3) Whether the global colour table (GCT) is sorted 4) the size of the GCT |
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What does the sixth byte of the Screen Descriptor of a GIF file describe? |
The background colour (represented using the index of the colour in the GCT) |
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What does the seventh byte of the Screen Descriptor of a GIF file describe? |
The Aspect Ratio |
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What is an example of lossless compression that isn't LZW? |
Run Length Encoding |
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How does Lossy Compression work? (what does it take advantage of?) |
Vision and Hearing |
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What does JPEG stand for? |
Joint Photographic Experts Group |
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Is JPEG true colour or Palette? |
True Colour |
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What is the first step of JPEG compression? |
Convert RGB to Brightness and Chromiance (Y, Cb, Cr) |
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What is Y in Y, Cb, Cr? |
Luma/Brightness |
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What are Cb and Cr in Y, Cb, Cr? |
Chroma |
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What is the second step in JPEG compression? |
Subsample by factor 2 (half resolution/share pixel values) |
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What is the third step in JPEG compression? |
Split image into 8 x 8 blocks and use Discrete Cosine Transform (DCT) |
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What is the fourth step in JPEG compression? |
Quantize Frequency Data (small variations in strength of high frequency brightness) |
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What is the eye more sensitive to; >Small variations in Brightness / colour >Strength of high frequency brightness changes |
Small variations in Brightness / Colour |
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What is the fifth step in JPEG compression? |
Use the huffman compression since there is now more repetition in the data |
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Is the first step in JPEG compression lossy or lossless? |
lossless |
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Is the second step in JPEG compression lossy or lossless? |
lossy |
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Is the third step in JPEG compression lossy or lossless? |
lossless |
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Is the fourth step in JPEG compression lossy or lossless? |
lossy |
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What does PNG stand for? |
Portable Network Graphics |
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What format is PNG similar to? |
GIF |
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Why was PNG originally created? |
To replace GIF due to patent issues |
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What can GIF do that PNG cannot |
Animation |
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What does TIFF stand for? |
Tagged Image File Format |
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By default does TIFF used lossy or lossless compression? |
Lossless or no compression |
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Does TIFF have one compression method available to it? |
No, it has a variety |
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What are bitmaps better at than vectors? |
Photorealism |
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Are vectors larger or smaller in size than bitmaps? |
smaller |
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What advantages are there to vectors rather than bitmaps? |
Searchable, modifiable at runtime, better for 3D, shiny and clean look |
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What does anti-aliasing do to pixels? |
Adds intensity
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What six shapes do vectors use? |
Lines, Rectangles, Ellipses, Regular Polygons, PolyLines, Bezier Curves |
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Is TrueType a bitmap or a vector font format? |
Vector |
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Define Internet |
An interconnected set of networks
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What does NIC stand for? |
Network Interface Card |
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How does a computer connect to an ISP? |
Computer -> NIC -> LAN -> ISP |
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What does JANET stand for? |
Joint Academic Network |
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What is the speed of JANET? |
2Tbit/s |
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What is the use of JANET |
To connect academic LANS |
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ARPAnet was the first ____. |
WAN |
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TCP/IP were introduced in _________ |
The early 80's |
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DNS was introduced in ________ |
The late 80's |
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The first WWW software was created by ____ in _____ |
CERN in 1992 |
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Define Interoperable in the context of the internet |
Any computer on the internet can communicate with any other computer |
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Name the five internet concepts. |
Interoperability Uniform Naming & Addressing Layering Abstraction End-to-End protocols |
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What is DNS used for? |
Translating human readable names to IP addresses |
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Are IPv4 and IPv6 interoperable? |
No |
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What are the four layers? |
Applications, Transport, Network, Link |
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Name a protocol associated with the Application layer |
HTTP/FTP... |
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Name the protocol associated with the Transport layer |
TCP/IP |
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What is associated with the Network Layer? |
IP |
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What three things are associated with the Link Layer? |
Ethernet, Token Ring, Asynchronous Transfer Mode |
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How many bits are used in an IPv4 address? |
32 bits |
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How many bits are used in an IPv6 address? |
128 - 4 groups of 4 hex values |
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What does MAC stand for? |
Media Access Control |
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What does EHA stand for? |
Ethernet Hardware Address |
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What is the MAC address associated with? |
The Network Interface Card or Adapter |
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What is a HUB used for? |
Connecting segments of LAN |
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What happens when a packet arrives at a HUB? |
It is copied to all Cegments of the LAN connected to the HUB. |
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What are three problems with HUBs? |
Bandwidth is quickly consumed as hosts are added Latency One device can cause problems (wrong broadcast speed) |
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What is the first piece of data in a packet? |
Control Info (Header) |
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What three things does the Header of a packet specify? |
Source, Destination, Error Detection Codes (such as Checksums) |
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What layer does the Router connect at? |
Network Layer |
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How does a router know where to send a packet? |
It has a local map of the network and uses it to forward the packet based on the IP |
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What is the second piece of information in a packet? |
User Data (Payload) |
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What is the transport layer useful for? |
Maintaining flow control of data error checking reliable byte stream |
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What can IP not support? |
Connection of two nodes |
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What does TCP do that IP cannot? |
Establish an initial connection between two nodes
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When a computer receives a TCP connection initiation request, what does it send back? |
An acceptance message containing its own IP and Port number. |
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If a server doesn't reply with an acknowledgement (ACK) message, what does the client do? |
Resend the TCP initiation packet |
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What does UDP stand for? |
User Datagram Protocol |
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What does TCP stand for? |
Transmission Control Protocol |
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What is the End-to-End principal |
Where data interpretation occurs on sending/receiving machines |
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What does the end-to-end principal mean in terms of abstraction? |
It hides the internal network structure |
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HTTP is Stateless. What does that mean? |
No connection info is maintained between transactions |
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What happens when a visitor to a website has no cookie? |
A new cookie is created for the user and a new ID is put into the database. |
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Why is XHTML considered stricter? |
It provides XML conformity and therefore is both case sensitive and requires terminating a tag |
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Why is XHTML not worth using? |
Not all browsers support it |
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What does ASP stand for? |
Active Server Pages |
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What does JSP stand for? |
JavaServer Pages |
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What does CGI stand for? |
Common Gateway Interface |
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What can a CGI be written in? |
Any language |
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What do Common Gateway Interfaces interface between? |
The server and an independent application |
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What are some problems with CGI? |
>Must be launched independent for each request >No convenient place to store state info >starting/stopping applications is difficult >Status and error reporting |
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Why is Java restricted in browsers? |
To avoid damage to client machines |
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What does RIA stand for? |
Rich Internet Application |
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Why are formats required in the context of video? |
For storage and transmission of video data. |
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How many encoding methods can a format have? |
One or more |
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Algorithms that handle compression and decompression of video are known as what? |
Codecs |
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What does M-JPEG compression ratio range from? |
2:1 to 12:1 |
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What is the first part of a video file? |
The header |
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What is the second part of a video file? |
The codec |
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What is the third part of a video file? |
The data |
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What does MPEG stand for? |
Motion Picture Experts Group |
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What spatial compression algorithm does MPEG use? |
Discrete Cosine Transform (DCT) |
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Are MPEG formats Symmetrical or Asymmetrical? |
Asymmetrical |
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What does an "Asymmetric Format" mean in terms of MPEG? |
It takes longer to compress than to decompress |
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What is temporal compression in terms of MPEG? |
Removing data that does not change between frames |
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What is the name of the sets of frames in MPEG videos? |
Group of Pictures |
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How many frames does each GOP hold? |
8 to 24 |
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What is the name of the first full frame in a GOP |
I Frame |
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What does I Frame stand for? |
Intra Frame |
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What is the first step of temporal compression? |
Split the image into 16 x 16 macroblocks |
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What is the second step of temporal compression? |
The reference frame (for example, the I frame) is scanned for the best match in the new frame |
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What are the three possibilities that can occur during the image scanning stage of Temporal Compression? |
> The part required is identical to the same area in the I Frame so no data needs to be stored > The part is different to any part of the I Frame and the new part is encoded as an I-Macroblock > The part is similar to part of the I-Frame so difference values and the motion vectors are stored |
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What two things could a P-Frame be encoded as? |
I-Macroblock or P-Macroblock |
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What is a P-Macroblock? |
An encoded area of a past reference frame, plus an error term |
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How is the previous location of a macroblock known? |
A motion vector is used |
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What does it mean if a macroblock's motion vector is 0? |
It has no movement |
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If the difference between the value of a macroblock and the reference frame is 0, what happens? |
The macroblock is not encoded |
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If a macroblock is not exactly the same as the area in the reference frame, what is stored? |
The difference values |
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What are the names of the two vector frames in MPEG? |
P-Frames and B-Frames |
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What does P-Frame stand for? |
Predictive Frame |
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What does B-Frame stand for? |
Bi-Directional Frame |
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Which Frame/Frames does/do P Frames refer to? |
The previous frame |
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Which Frame/Frames does/do B Frames refer to? |
Previous and subsequent frames |
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What resolution did MPEG-1 support? |
352 x 288 @ 25 fps |
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What resolutions did MPEG-2 support? |
720 x 576 @ 50 fps 1280 x 720 @ 50 fps |
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How many Kbit/s audio did MPEG-1 support? |
192 |
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Which MPEG format did DVD-ROMs use? |
MPEG-2 |
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What does ASP stand for in terms of MPEG-4? |
Advanced Simple Profile |
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What does AVC stand for? |
Advanced Video Coding |
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What is part 14 for MPEG-4? |
A multimedia container standard (MP4) |
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How many reference frames could be used for B frames before MPEG-4? |
2 |
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How many reference frames could be used for B frames with MPEG-4? |
16 |
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What does VBSMC stand for? |
Variable Block Size Motion Compression |
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What size blocks does VBSMC support? |
16 x 16 to 4 x 4 |
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What does AVI stand for? |
Audio Video Interlace |
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What does WMV stand for? |
Windows Media Video |
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Why is WMV considered popular? |
It's the format used for blue-ray discs |
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What is the aim of web video? |
To provide searchable and immediately available network content |
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What are the 4 web video categories? |
Downloadable File Progressive Download Real-time streaming Multicasting |
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Is Progressive Download lossy or lossless? |
lossless |
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Can playing ever catch up with downloading in Progressive Downloads? |
In theory, no |
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What is a problem with viewing a video using Progressive Downloads? |
Users cannot navigate beyond the point downloaded |
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Why is Real-Time streaming more costly? |
It requires a dedicated server |
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What are the three streaming components? |
Players Encoders Servers |
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In terms of Streaming Components, what is between Players and Servers? |
Compatible Protocols |
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In terms of Streaming Components, what is between Players and Encoders? |
Compatible Codec |
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In terms of Streaming Components, what is between Encoders and Servers? |
Compatible File Format |
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What is a Streaming Media Server? |
An Application that runs on an internet server |
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What is the benefit of using a Streaming Media Server? |
It can handle large traffic loads Can Identify users speed and supply appropriate files Enables the broadcast of live events |
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What does RTSP stand for? |
Real-Time Streaming Protocol |
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What does RTP stand for? |
Real-Time Transport Protocol |
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Does RTSP handle the sending of streaming data? |
No |
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What does RTSP use to handle the sending of streaming data? |
RTP |
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Does RTP guarantee quality? |
No |
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When enough packets have been received by the client, what three things can the user's software do? |
Play one packet Decompress another Download a third |
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What can RTSPs not achieve? |
end-to-end interoperability |
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What is the layout for a live streamed broadcast? |
Camera > Encoder > streaming format > server > video stream > player |
