How to calculate PSNR in Matlab Figure file?

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Star Rats 2020-4-23

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/520089-how-to-calculate-psnr-in-matlab-figure-file

评论： Star Rats 2020-7-18

采纳的回答： Mehmed Saad

在 MATLAB Online 中打开

I wish to calculate the PSNR between two signals.

The input file would be Matlab Figure file.

signal1 = openfig('Figure1.fig');
signal2 = openfig('Figure2.fig');
[R C]=size(signal1);
err = sum((signal1-signal2).^2)/(R*C); 
MSE=sqrt(err);
MAXVAL=65535;
PSNR = 20*log10(MAXVAL/MSE); 
disp(MSE);
disp(PSNR);

However, the error shows:

Operator '-' is not supported for operands of type 'matlab.ui.Figure'.
Error in file (line 4)
err = sum((signal1-signal2).^2)/(R*C);

How can I solve the error?

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Answer 1

Mehmed Saad 2020-4-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/520089-how-to-calculate-psnr-in-matlab-figure-file#answer_427849

在 MATLAB Online 中打开

signal1 = openfig('Figure1.fig');
signal2 = openfig('Figure2.fig');

signal1 contains the figure handle not the data

you have to extract data from figure handle, you cannot directly subtract two figures data by subtracting there handle

to extract data from figure handle (assuming they contain 1 line only)

data1 = signal1.Children(1).Children(1).YData;
data2 = signal2.Children(1).Children(1).YData;

Now you can process data1 and data2 from here after

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Mehmed Saad 2020-4-24

在 MATLAB Online 中打开

your matrix are not of same dimension.

There are two possible things in this contex which make there dimension different

sampling rate
time of signal

to get the time signal from plots

t1 = signal1.Children(1).Children(1).XData;
t2 = signal2.Children(1).Children(1).XData;

Now you have to check if their sampling rates are same or not and their ending times are same or not

if their sampling rate is same but ending time is not, truncate the longer time signal
f their time ends at the time then they have different sampling rate. you either have to upsample the low sampling signal or downsample the high sampling signal so that both signal are of same sampling rate
if ending time and sampling rate both are not matching, first match the time and then follow the step 2

Now you have to do it yourself. it is basic matrix operation.

Star Rats 2020-7-18