What is the difference between PCM and quantization?

In summary, PCM (Pulse Code Modulation) is a simple method of converting analog data into a digital data stream. Your professor may be asking you to use PCM on an image in MATLAB to reduce the bits per pixel, which may seem unreasonable at first glance. However, it is possible that he simply wants you to group the finely spaced levels of the original image into coarser levels, which is a relatively easy task and can enhance the visualization of certain surfaces. It would be helpful to refer to your lecture notes for further clarification on the specific requirements.
  • #1
Boltzman Oscillation
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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?
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  • #3
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.
 
  • #4
Boltzman 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.
 

What is the difference between PCM and quantization?

PCM (Pulse Code Modulation) is a method of converting analog signals into digital signals by sampling the signal at regular intervals and assigning numerical values to each sample. Quantization is the process of converting these numerical values into discrete levels to reduce the amount of data needed to represent the signal.

How does PCM work?

PCM works by sampling an analog signal at regular intervals and converting each sample into a binary number. These numbers are then transmitted or stored as digital data, which can be reconstructed back into an analog signal by a digital-to-analog converter.

What is the purpose of quantization in PCM?

The purpose of quantization in PCM is to reduce the amount of data needed to represent an analog signal. By converting the numerical values into discrete levels, the amount of data can be significantly reduced without losing too much information about the original signal.

What are the advantages of using PCM over analog signals?

There are several advantages of using PCM over analog signals. PCM allows for more efficient transmission and storage of data, as well as better error correction and noise reduction. It also allows for easier processing and manipulation of the signal, making it more versatile for various applications.

What are the limitations of quantization in PCM?

The main limitation of quantization in PCM is that it can introduce quantization error, which is the difference between the original analog signal and the reconstructed signal. This can result in a loss of fidelity and accuracy in the reconstructed signal. Additionally, quantization can also introduce distortion in the signal, particularly at lower bit depths.

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