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

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)

Answer 1

[Walter Roberson]

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

[Amirullah Bin Abdul Razak]

Hi, There are a total of 750 frames for my video file.. just to clarify,is vid1 and vid2 referring to the same video file? Coz I see it's using different file name.. as for the reference image should I just attached the first frame only? Thanks..

[Walter Roberson]

D:\ is a give-away that this code is intended for a Windows system. For Windows NTFS file systems the default is not case sensitive, so Traffic and traffic would be the same file.

You do not attach any reference image. The code automatically takes the last image of the video as the reference image. It would be more efficient to use the first image but the code was not designed for efficiency.

[Amirullah Bin Abdul Razak]

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]

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