CSE 126/228F: FIRST HOMEWORK

DUE May 4  IN CLASS Write a short discussion for each of the following questions. This homework is due at the beginning of class on May 4; no late homeworks will be accepted. Typed homeworks are preferred. If you do turn in handwritten material it must be extremely legible. Please use a stapler.


  1. Multimedia: Color Concepts: 2 points
    1. Compare three systems for color image representation. Give two techniques for reducing the number of bits in color representation.


  2. Television Data Rates: 4 points
    1. How does television solve the problem of flicker in display?
    2. Compute the data rates in bits per second for uncompressed video captured in the following formats: NTSC, PAL, and HDTV. If you know of several sub-formats for each of the above three formats, go ahead and use one of those sub-formats.


  3. Audio Coding: 6 points
    1. Describe the various steps in digitization and coding of audio signals.
    2. The following sequence of real numbers has been obtained sampling an audio signal:
      1.8, 2.2, 2.2, 3.2, 3.3, 3.3, 2.5, 2.8, 2.8, 2.8, 1.5, 1.0, 1.2, 1.2, 1.8, 2.2, 2.2, 2.2, 1.9, 2.3, 1.2, 0.2, -1.2, -1.2, -1.7, -1.1, -2.2, -1.5, -1.5, -0.7, 0.1, 0.9
      Quantize this sequence by dividing the interval [-4, 4] into 32 uniformly distributed levels (place the level 0 at -3.75, the level 1 at -3.5, and so on. This should simplify your calculations). Write down the quantized sequence. How many bits do you need to transmit it?
    3. Encode the quantized sequence using DPCM and use a Huffman code on the difference samples. How many bits do you need now to encode the sequence?
    4. What is the compression ratio you have achieved?


  4. Video Coding: 4 points
    1. Differentiate between Subband coding and Subsampling.
    2. Will Transform coding always result in compression? Explain with an example.


  5. JPEG: 4 points
    1. Are the 8x8 blocks within an image coded independently of each other? In other words, if for example, if a decoder receives all blocks except the first one, can it go ahead and construct most of the image (except of course the region covered by the first block)? Explain.
    2. What is the reason for zig-zag coding of AC Coefficients?
    3. Give 3 methods for encoding multiple resolutions in JPEG.


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