What is the difference between PCM and quantization?

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Discussion Overview

The discussion revolves around the differences between Pulse Code Modulation (PCM) and quantization, particularly in the context of applying PCM to image processing in MATLAB. Participants explore the implications of using PCM for reducing bits per pixel in images.

Discussion Character

  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • Some participants assert that PCM is a method for coding analog data into a digital stream, referencing its definition.
  • One participant questions the appropriateness of a professor's assignment to apply PCM to image data, expressing frustration and seeking confirmation on the task's validity.
  • Another participant elaborates on PCM, suggesting it involves selecting a sampling rate and quantization interval, and proposes that the professor may simply be asking for a grouping of pixel values into coarser levels.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the appropriateness of the professor's assignment, with some expressing doubt while others provide potential clarifications on what PCM entails.

Contextual Notes

There are unresolved assumptions regarding the definitions of PCM and quantization, as well as the specific requirements of the professor's assignment.

Boltzman Oscillation
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TL;DR
For a project I am asked to do PCM on a 255 by 255 image. I don't understand, PCM is used to convert analog to digital. As it turns out, the answer to the project was to use quantization of the image. So is PCM just another term for quantization?
Summary
 
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Svein said:
No, PCM is a very simple way of coding analog data into a digital data stream. See https://en.wikipedia.org/wiki/Pulse-code_modulation.
Then is it fair for my professor to want me to do PCM on an image in MATLAB to reduce the bits per pixel? I think not but I want confirmation because this is driving me insane.
 
Boltzmann Oscillation said:
Then is it fair for my professor to want me to do PCM on an image in MATLAB to reduce the bits per pixel? I think not but I want confirmation because this is driving me insane.
The PCM I know is Pulse Code Modulation, which I understand to be the catch-all term for all digitisation. Before we go further, is this what your lecture notes are telling you? On the face of it, he seems to be making an unreasonable demand - but perhaps it's not actually what he said / wrote.
PCM entails choosing a sampling rate (pixel size) and a quantisation interval. Perhaps all your Prof wants you to do is to group your finely spaced levels of the original into coarser levels. So levels 1,2,3,4,5,6,7,8 become 1,1,1,1,5,5,5,5 etc. Easy to do and the results will show, particularly where you have a gently graded surface which starts to show contours.
 

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