Matlab PSNR calculation Example code | Matlab Peak Signal to Noise Ration calcylation

Peak signal to noise ration calculation used as following areas,

1. Image Compression
2. Watermarking
3. Signal processing
   

and more areas its used.PSNR Matlab code as follows

A = imread('input.jpg');
B = imread(output.jpg');

max2_A = max(max(A));
max2_B = max(max(B));
min2_A = min(min(A));
min2_B = min(min(B));

if max2_A > 255 || max2_B > 255 || min2_A < 0 || min2_B < 0
error('input matrices must have values in the interval [0,255]')
end

error_diff = A - B;
decibels = 20*log10(255/(sqrt(mean(mean(error_diff.^2)))));
disp(sprintf('PSNR = +%5.2f dB',decibels))


In above PSNR code only used in Image processing area.

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Matlab multiple Plots on one Figure Window | Matlab multiple Plots on same Figure window

Here we see multiple Plots on same Figure window on Matlab. This type of graphs used for comparisons.You have put legend for each comparison. Its very simple to make it easy ,just use following syntax .Its very helpful to you.

>>figure;
>>plot(x1,y1);
>>hold on
>>drawnow
>>plot(x2,y2);
>>plot(x3,y3);
>> "
>> "
>> " ect..

example as follows
>> x1 = 1:5;
>> y1 = rand(1,5);
>> y2 = rand(1,5);
>> y3 = rand(1,5);
>> figure;plot(x1,y1);
>> hold on
>> drawnow
>> plot(x1,y2,'color','red');
>> plot(x1,y3,'color','green');

out put as follows. after plotting you have put the legend for each color plot comparison. ie( legend ('Blue','Red','Green')).

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Multilevel 2-D Wavelet Decomposition Example code | Multilevel Matlab 2-D Wavelet examples

In below example to support for multilevel 2-D wavelet decomposition on Matlab.below syntax used to create your Multilevel 2-D Wavelet.

In matlab wavedec2 use this function for multilevel 2d- wavelet example as below.

>>N = 3; % 3-level 2d wavelet....

>>X = imread('input.jpg');

>>imshow(X);

>> [C,S] = wavedec2(X,N,'haar'); % we choosing haar wavelet.. C is band ,S is coefficients of bands

C is band value .Change bands values

In below we applying inverse multilevel 2d wavelet....

>>output = waverec2(C,S,'haar');

>>imshow(output);

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Single Level 2d Discrete Wavelet Transform Matlab Example code | Single Level 2d Wavelet Transform Code on Matlab

In below example to applying single level wavelet transform.

Wavelets are convert the signal into more sub bands like low frequency and high frequency. wavelets used in stenography and watermarking techniques.

>> input = imread('input.jpg');

>> imshow(input);

>>[LL,LH,HL,HH] = idwt2(input,'haar'); % here we use haar wavelet applying

then process and covert any one bands.then applying inverse operation,example as below

>>out_img = idwt2(LL,LH,HL,HH);

>>imshow(out_img );

Finally we construct new image.

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