I want a differential pulse code modulation(DPCM) matlab code for images

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tina jain
tina jain 2015-5-23
评论： Walter Roberson 2015-5-23
how to apply DPCM on images

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Walter Roberson
Walter Roberson 2015-5-23
See http://www.mathworks.com/help/comm/ug/differential-pulse-code-modulation.html
You can reshape() the image array into a vector in order to create a "signal" that you apply DPCM to. It might not be very effective, but if someone promised that DPCM is useful for images then you should write the code to follow their algorithm.
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tina jain
tina jain 2015-5-23
编辑：Walter Roberson 2015-5-23
see Walter sir, I used the code below
close all;
clear all;
clc;
predictor = [0 1]; % y(k)=x(k-1)
partition = [-1:.1:.9];
codebook = [-1:.1:1];
y=imread('lena256.bmp');
y=double(y);
x = y(:);
t = linspace(1, 2*pi, length(x));
% Quantize x using DPCM.
encodedx = dpcmenco(x,codebook,partition,predictor);
% Try to recover x from the modulated signal.
decodedx = dpcmdeco(encodedx,codebook,predictor);
plot(t,x,t,decodedx,'--')
xx =decodedx(:);
[psnrtest]=psnr(x,xx)
legend('Original signal','Decoded signal','Location','NorthOutside');
is it ok?
PSNR is only 15
Walter Roberson
Walter Roberson 2015-5-23
Shrug. I am not expecting a good PSNR for arbitrarily chosen codebook and partitions and arbitrary reordering of the image into a signal.

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