Motion Detection - background image subtraction

One of the most common approaches is to compare the current frame with the previous one. It's useful in video compression when you need to estimate changes and to write only the changes, not the whole frame. But it is not the best one for motion detection applications.

here the process i used:

1. get each frames pixel and normalize to 255
2. Convert it to gray scale
3. subtract pixels from previous pixels (previous post subtracted images)
4. show each image in a sequence

heres the code:

clear all
close all
clc;
disp('Testing Purposes Only....');
fin = 'smallVersion.avi';
avi = aviread(fin);

% Convert to RGB to GRAY SCALE image.
avi = aviread(fin);
pixels = double(cat(4,avi(1:2:end).cdata))/255; %get all pixels (normalize)
nFrames = size(pixels,4); %get number of frames

for f = 1:nFrames
pixel(:,:,f) = (rgb2gray(pixels(:,:,:,f))); %convert images to gray scale
end

nrames=f;
for l = 2:nrames
%d(:,:,l)=(abs(pixel(:,:,l)-pixel(:,:,1))); %subtract current pixel from background
z(:,:,l)=(abs(pixel(:,:,l)-pixel(:,:,l-1))); %subtract current pixel from previous pixel

%imshow(d(:,:,l));
imshow(z(:,:,l));

hold on
drawnow;
hold off

end

Results:

Image 1: Frame subtracted from Background or first frame (overlaps)

Image 2: Frame subtracted from previous Frame