Hi sorry im new to image processing. Need some explanation , which 2 video attachment should I use for this MATLAB code and which reference image i should use? thank you

Question

Amirullah Bin Abdul Razak 2023-1-19

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https://ww2.mathworks.cn/matlabcentral/answers/1896975-hi-sorry-im-new-to-image-processing-need-some-explanation-which-2-video-attachment-should-i-use-f

评论： Walter Roberson 2023-1-22

clc;
close all;
inputvideo=vision.VideoFileReader('traffic.avi');%<<<<<<<<<<<<
vid1=vision.VideoPlayer;
while~isDone(inputvideo)
    frame1=step(inputvideo);
    step(vid1,frame1);
    pause(0.005);
end
imwrite(frame1,'D:\referenceimage.jpg','jpg');%<<<<<<<<<<<<<<
release(inputvideo);
release(vid1);
referenceimage=imread('D:\referenceimage.jpg');<<<<<<<<<<<<
vid2=vision.VideoFileReader('Traffic.avi');%<<<<<<<<<<<<<
X=zeros(2,121);
Y=zeros(2,121);
Z=zeros;
for i=2:121
    clc
    frame=step(vid2);
    frame2=((im2double(frame))-(im2double(referenceimage)));
    frame1=im2bw(frame2,0.2);
    [labelimage]=bwlabel(frame1);
    stats=regionprops(labelimage,'basic');
    BB=stats.BoundingBox;
    X(i)=BB(1);
    Y(i)=BB(2);
    Dist=((X(i)-X(i-1))^2+(Y(i)-Y(i-1))^2)^(1/2);
    Z(i)=Dist;
    if(Dist>10&&Dist<20)
        display('MEDIUM SPEED');
    elseif(Dist<10)
        display('SLOW SPEED');
    else
        display('FAST SPEED');
    end
    S=strel('disk',6);
    frame3=imclose(frame1,S);
    step(vid1,frame1);
    pause(0.05);
end
M=median(Z);
Speed=(M)*(120/8);
release(vid1)

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Answer 1

Walter Roberson 2023-1-19

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traffic.avi is supplied with the Image Processing Toolbox.

The code reads and displays the content of the avi. The last frame is written to a file and then the file is read back in. It is not clear why the code bothers to write to a file and read back when it could have just used the content of frame1

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Amirullah Bin Abdul Razak 2023-1-22

Hi ,

Should I just delete off these two lines of just leave as it is from the program code? ''

imwrite(frame1,'D:\referenceimage.jpg','jpg');%<<<<<<<<<<<<<<

release(inputvideo);

release(vid1);

referenceimage=imread('D:\referenceimage.jpg');<<<<<<<<<<<<

vid2=vision.VideoFileReader('Traffic.avi');%<<<<<<<<<<<<<

X=zeros(2,121);

Y=zeros(2,121);

Z=zeros;

for i=2:121

clc

frame=step(vid2);

frame2=((im2double(frame))-(im2double(referenceimage)));

Walter Roberson 2023-1-22

在 MATLAB Online 中打开

FramesToProcess = 121;    %don't ask me why
videoname = 'traffic.avi';
inputvideo = VideoReader(videoname);
vid1 = vision.VideoPlayer;
while hasFrame(inputvideo)
    frame1 = readFrame(inputvideo);
    step(vid1,frame1);
    pause(0.005);
end
referenceimage = frame1;
inputvideo.CurrentTime = 0;  %reset to beginning instead of release and reopen
vidlength = inputvideo.NumFrames;
if vidlength < FramesToProcess
    clear inputvideo
    error('video only has %d frames, need %d', vidlength, FramesToProcess);
end
X = zeros(2,FramesToProcess);
Y = zeros(2,FramesToProcess);
Z=zeros;
for i = 2:FramesToProcess
    frame = read(inputvideo, i);
    frame2=((im2double(frame))-(im2double(referenceimage)));
    frame1=im2bw(frame2,0.2);
    [labelimage]=bwlabel(frame1);
    stats=regionprops(labelimage,'basic');
    BB=stats.BoundingBox;
    X(i)=BB(1);
    Y(i)=BB(2);
    Dist=((X(i)-X(i-1))^2+(Y(i)-Y(i-1))^2)^(1/2);
    Z(i)=Dist;
    if(Dist>10&&Dist<20)
        display('MEDIUM SPEED');
    elseif(Dist<10)
        display('SLOW SPEED');
    else
        display('FAST SPEED');
    end
    S=strel('disk',6);
    frame3=imclose(frame1,S);
    step(vid1, frame3);     %not frame1 !
    pause(0.05);
end
M=median(Z);
Speed=(M)*(120/8);
release(vid1)
clear inputvideo