motion estimation

Author: yolanda93

Motion-Estimation/Block_Matching.m

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+function [ x_predicted, y_predicted, min_MSE ] = Block_Matching( reference_frame, new_frame, p, x, y, block_size  )
+%Block_Matching Algorithm. Block Matching between 2 subsequent frames to detect motion estimation
+%   reference_frame   The frame{t-1}
+%   new_frame         The frame{t}
+%   p                 Search parameter
+%   x,y               Position withing the frame
+%   block_size        Size of the macroblock
+
+reference_block = reference_frame(x:x+block_size,y:y+block_size,:);
+MSE = zeros(p,p);
+
+for new_xpos=x-p:1:x+(p-1)
+    for new_ypos=y-p:1:y+(p-1)
+        if(new_xpos+block_size>size(reference_frame,1) || new_ypos+block_size>size(reference_frame,2) || new_xpos<=0 || new_ypos<=0)
+          MSE(new_xpos-(x-p)+1,new_ypos-(y-p)+1)=1000;
+        else
+          new_block =new_frame(new_xpos:new_xpos+block_size,new_ypos:new_ypos+block_size,:);
+          MSE(new_xpos-(x-p)+1,new_ypos-(y-p)+1)=double(mean2(((reference_block-new_block).^2)));
+        end
+    end
+end
+
+min_MSE = min(min(MSE));
+
+[min_x,min_y]=find(min_MSE);
+
+if(isempty(min_x)&&isempty(min_y)) % no movement detected
+ x_predicted = x;
+ y_predicted = y;
+else
+  x_predicted = min_x+(x-p);
+ y_predicted = min_y+(y-p);
+end    
+
+end
+

Motion-Estimation/script.asv

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+video=VideoReader('../Test-images/Xylophone.mp4');
+n=video.NumberofFrames;
+
+% Divide the video in frames
+for x=1:n
+frame=read(video,x);
+imwrite(frame,sprintf('../Test-images/Frames/image%d.jpg',x));
+end
+
+% Compute the motion vectors between 2 frames
+reference_frame = imread('../Test-images/Frames/image40.jpg');
+new_frame = imread('../Test-images/Frames/image41.jpg');
+
+figure;imshow(reference_frame),title('Reference Frame');imshow(new_frame),title('New Frame');
+
+tic
+% Motion Estimation
+p=3;block_size=16;
+predicted_pos = zeros(round(size(reference_frame,1)/block_size),round(size(reference_frame,2)/block_size),2);
+i=1;j=1;
+%Display the optical flow
+figure;imshow(reference_frame),title('Motion Vectors');
+hold on;
+for posx = 1:block_size:size(reference_frame,1)-block_size
+    for posy = 1:block_size:size(reference_frame,2)-block_size
+          [predicted_posx,predicted_posy,min_MSE]=Block_Matching( reference_frame, new_frame, p, posx, posy, block_size  );
+          if(min_MSE>=0.4)
+            fprintf('ovement detected, draw motion vectors')
+            quiver(posx, posy, predicted_posx,predicted_posy,'color', 'b', 'linewidth', 1);
+          end     
+    end
+end
+toc
+
+%Display the optical flow
+figure;imshow(reference_frame),title('Optical Flow');
+hold on;
+for i = 1:size(predicted_pos,1)
+    for j = 1:size(predicted_pos,2)
+        if(predicted_pos(i,j,1)~=i ||predicted_pos(i,j,2)~=j)
+           quiver(i, j, predicted_pos(i,j,1),predicted_pos(i,j,2),'color', 'b', 'linewidth', 1);
+        end
+    end
+end
+
+
+% Predict the next frame between 2 frames taken randomly
+reference_frame = imread('../Test-images/Frames/image1.jpg');
+
+tic
+% Predict image
+p=3;block_size=16;N=2;
+MSE_frames = zeros(1,N);
+for i = 1:1:N
+    min_MSE=0;
+    path = sprintf('../Test-images/Frames/image%d.jpg',i);
+    new_frame = imread(path);
+    for posx = 1:size(reference_frame,1)
+        for posy = 1:size(reference_frame,2)
+            if(posx+block_size<size(reference_frame,1) && posy+block_size<size(reference_frame,2))
+               [~,~,MSE]= Block_Matching( reference_frame, new_frame, p, posx, posy, block_size  );
+              min_MSE= min_MSE + MSE;
+            end
+        end
+    end
+    fprintf('Mean Square Error: %d \n',min_MSE);
+    MSE_frames(i) = min_MSE;
+end
+toc
+pred_frame = find(min(MSE_frames(i)));
+fprintf('The predicted frame is: %d \n',pred_frame);
+
+PSNR=10*(log(255^2/MSE_frames(pred_frame))/log(10));
+fprintf('Peak-Signal-To-Noise Rario of the predicted frame: %d \n',PSNR);

Motion-Estimation/script.m

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+video=VideoReader('../Test-images/Xylophone.mp4');
+n=video.NumberofFrames;
+
+% Divide the video in frames
+for x=1:n
+frame=read(video,x);
+imwrite(frame,sprintf('../Test-images/Frames/image%d.jpg',x));
+end
+
+% Compute the motion vectors between 2 frames
+reference_frame = imread('../Test-images/Frames/image40.jpg');
+new_frame = imread('../Test-images/Frames/image41.jpg');
+
+figure;imshow(reference_frame),title('Reference Frame');imshow(new_frame),title('New Frame');
+
+tic
+% Motion Estimation
+p=3;block_size=16;
+predicted_pos = zeros(round(size(reference_frame,1)/block_size),round(size(reference_frame,2)/block_size),2);
+i=1;j=1;
+%Display the optical flow
+figure;imshow(reference_frame),title('Motion Vectors');
+hold on;
+for posx = 1:block_size:size(reference_frame,1)-block_size
+    for posy = 1:block_size:size(reference_frame,2)-block_size
+          [predicted_posx,predicted_posy,min_MSE]=Block_Matching( reference_frame, new_frame, p, posx, posy, block_size  );
+          if(min_MSE>=0.4)
+            fprintf('Movement detected, draw motion vectors')
+            quiver(posx, posy, predicted_posx,predicted_posy,'color', 'b', 'linewidth', 1);
+          end     
+    end
+end
+toc
+
+% Predict the next frame between 2 frames taken randomly
+reference_frame = imread('../Test-images/Frames/image1.jpg');
+
+tic
+% Predict image
+p=3;block_size=16;N=2;
+MSE_frames = zeros(1,N);
+for i = 1:1:N
+    min_MSE=0;
+    path = sprintf('../Test-images/Frames/image%d.jpg',i);
+    new_frame = imread(path);
+    for posx = 1:size(reference_frame,1)
+        for posy = 1:size(reference_frame,2)
+            if(posx+block_size<size(reference_frame,1) && posy+block_size<size(reference_frame,2))
+               [~,~,MSE]= Block_Matching( reference_frame, new_frame, p, posx, posy, block_size  );
+              min_MSE= min_MSE + MSE; % Compute the sum between all macroblocks 
+            end
+        end
+    end
+    fprintf('Mean Square Error: %d \n',min_MSE);
+    MSE_frames(i) = min_MSE;
+end
+toc
+pred_frame = find(min(MSE_frames(i)));
+fprintf('The predicted frame is: %d \n',pred_frame);
+
+PSNR=10*(log(255^2/MSE_frames(pred_frame))/log(10));
+fprintf('Peak-Signal-To-Noise Rario of the predicted frame: %d \n',PSNR);