What is the difference between PCM and quantization?

[Boltzman Oscillation]

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

 

[Svein]

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.

 

[Boltzman Oscillation]

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.

 

[sophiecentaur]

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.