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% this code is able to track an object within a video, to plot the
% trajectory and to calculate the velocity of the object
% initialisations
template_rows = 1;
template_columns = 1;
template_xmin = 1;
template_ymin = 1;
% importation of the video
video = aviread('number 2.avi');
% video_info is used to store the information about the video
% (number of frames, format of frames, number of frames per second...)
video_info = aviinfo('number 2.avi');
NumFrames = video_info.NumFrames;
FPS = video_info.FramesPerSecond;
% the crop function is used here to extract the ultrasound image from all
% frames
% for example sometimes the frames have a Title and some comments that the
% program doesn't need for the processing
% this enables to reduce the running time of the program
% the user selects a rectangle containing the ultrasound image
[crop,rect_image2] = imcrop(video(1).cdata);
% the loop extract the ultrasound image part of each frames
for j=1:NumFrames
video(j).cdata = imcrop(video(j).cdata,rect_image2);
video(j).cdata = rgb2gray(video(j).cdata);
end
image1 = video(1).cdata;
[frame_rows,frame_columns] = size(image1);
% the crop function is used here to select the object that he is interested
% in finding the trajectory and velocity of
[template,rect_image1] = imcrop(image1);
% the code below is saving informations about the rectangle selected by the
% user (size, position ...)
size_template = size(template);
template_rows = size_template(1);
template_columns = size_template(2);
template_width = template_columns - 1;
template_height = template_rows - 1;
if rect_image1(1)<1
rect_image1(1)=1;
end
if rect_image1(2)<1
rect_image1(2)=1;
end
% the coordinates of the object are saved
x_coordinates(1,1) = round(rect_image1(1))+((template_columns-1)/2);
y_coordinates(1,1) = round(rect_image1(2))+((template_rows-1)/2);
% the loop below computes the cross-correlation and finds the coordinates of
% the object in all frames of the video
for k=2:NumFrames
image2 = video(k).cdata;
corr = normxcorr2(template,image2);
% the program using the function max_corr
[corr_max_row,corr_max_column]=max_corr(corr);
% this part is computing the updating of the template
template_xmin = corr_max_column - template_width;
template_ymin = corr_max_row - template_height;
rect_template = [template_xmin, template_ymin, template_width, template_height];
template = imcrop(image2,rect_template);
% the coordinates of the object are saved
x_coordinates(1,k) = corr_max_column - ((template_columns-1)/2);
y_coordinates(1,k) = corr_max_row - ((template_rows-1)/2);
end
for i=1:NumFrames
y_coordinates(1,i)=frame_rows - y_coordinates(1,i);
end
% the program asks the user to enter the frame length scale
Scale = input('Dimension of the frames (in mm):\n');
% the pixel length and the time between two consecutive frames are
% calculated
pixel_length = Scale/frame_columns;
deltaT = 1/FPS;
% the loop below calculates the velocity of the object for each frames
for k=2:NumFrames-1
offset_x = sqrt((x_coordinates(1,k+1)-x_coordinates(1,k-1))^2);
offset_y = sqrt((y_coordinates(1,k+1)-y_coordinates(1,k-1))^2);
velocity(1,k-1) = (sqrt(offset_x^2 + offset_y^2))/(2*deltaT);
end
% this corresponds to the plotting of the trajectory
subplot(2,1,1), plot(x_coordinates,y_coordinates,'o');
axis([0 frame_columns 0 frame_rows]);
xlabel('Pixels in the x axis');
ylabel('Pixels in the y axis');
title('trajectory of the object')
subplot (2,1,2), plot(velocity);
title ('velocity of the object');
% the code below displays the velocity table
velocity(:,:) |
Vitesse et déplacement de nerfs humains à partir d'une vidéo ultrason
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ton poste tu dois marquer quand la bonne réponse tu as obtenu.
il n'y a pas un bug quelque part ? 
Tu peux l'essayer pour commencer mais j'ai un doute.
Envoyé par muchon
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