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Sistemas-Multimedia / MRVC

A scable-in-resolution video codec
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(Week 5) Visual evaluation of the effects of quantization #32

Closed vicente-gonzalez-ruiz closed 5 years ago

vicente-gonzalez-ruiz commented 5 years ago

Objectives

  1. Understand the importance of quantization in image coding.
  2. Measure the visual impact of the quantization error in MCDWT.

Methodology

In groups, research the links provided below (and in general, use all the information that you can be found on the Internet) to see how quantization affects both, the quality of the reconstructions and the compression ratio. Next, implement a subband quantizer that inputs an image and outputs a quantized image, after providing the quantization step as a parameter. Use this quantizer to degrade the quality of the output of MCDWT applied to a sequence of images, in two cases: (1) when only the H subbands are quantized, and (2) when all the subbands (L included) are quantized. Visually determine the impact of quantization in both cases.

Contents

  1. MCDWT white paper.
  2. MCDWT.
  3. Introduction to Data Compression.
  4. Video compression.
  5. Quantization.

Activities

  1. Research on the Internet looking for quantization in image compression.
  2. Implement a script to quantize (PNG) images (implement an uniform scalar quantizer). The name of the file with the image and the quantization step should be provided as input parameters. The name of the quantized image is the only output.
  3. Compute an MCDWT of T temporal levels and K spatial levels.
  4. Quantize the H subbands.
  5. Compute the inverse MCDWT and visualize the reconstruction.
  6. Compare (visually) the reconstruction and the original sequence.
  7. Repeat this procedure for several T and K values.
  8. Repeat the procedure when all the subbands (L and H) are quantized.
  9. Write a report (use preferably Markdown) describing your experiments and your conclusions.
vicente-gonzalez-ruiz commented 5 years ago

Done