motion detection?

Posted on 2001-09-13
Last Modified: 2010-05-18
any algorithm for analysing pictures and reporting if any motion detected? any ideas where to start searching on this subject?

Question by:zastava101

Expert Comment

ID: 6481318
As a start, you can subtract an image from a later one. Only moving objects and noise will appear in the difference. The edges are highlighted for the objects that move, in the direction of motion. You can use this to measure the motion.

Cross correlation will let you pick similar obejcts out between two images.

You should learn about fourier transforms to understand some of the details.


Jaehne Digital image processing 1991 Springer
Pratt Digital image processing 1991 Wiley
Gonzalez, Woods Digital image processing 1992 Adison Wesley
and Lim

To experiment you could start with subrtaction, use an offset to stop numbers going negative.

One way of looking at motion is that you are looking at tited objects in the 3D space of images. (stationary objects form pillars in this space, the same in every plane)

Good motion detection is critical to Mpeg4 encoding, so it is a very current field.


Expert Comment

ID: 6481344
the logitech quickcam (a very inexpensive webcam) has some algorithms for motion detection.  Check for more info about webcams and the SDK for quickcam programming (there is a way to link it to delphi. Search also here for webcam programming and Delphi).

Hope this help.
Manuel Lopez (lopem)
LVL 11

Expert Comment

ID: 6481492
OpenCV from Intel is a Open Source project for image algorithms. It is in C, but accessing the DLLs from Delphi should be possible.
Search Intels website for "OpenCV". There is a mailinglist at
Join by sending an empty message to
LVL 12

Accepted Solution

Lee_Nover earned 100 total points
ID: 6482044
hi .. I have the code made in Delphi
it uses FastLib components (free)
here it is

add fastdib, fastblend, FConvert, FastFX to uses clause

  oldDIB, newDIB, diffDIB: TFastDIB;
  lastBMP: TBitmap;

// I just took the code out and put it in this dummy procedure
procedure DetectMotion;
var C, w, h, x, y, t: Integer;
    // load the new bitmap from anywhere

     if lastBMP.Handle = 0 then exit;
        oldDib.MakeCopy(newDib, true);

        // load the source .. then copy it grayscale to newDIB

        FConvert.ConvertTo(diffDIB, 16);
        FastFX.Grayscale(diffDIB, newDIB);

        diffDIB.MakeCopy(oldDIB, true);
        FastFX.Grayscale(diffDIB, oldDIB);
        FConvert.ConvertTo(diffDIB, 8);

        FastBlend.DifBlend(diffDIB, oldDIB, newDIB);


        for x:=0 to w do
            for y:=0 to h do
                Inc(C, diffDIB.GetPixelB(y, x));


     if (c = 0) then
     else// number of pixels * number of bits
        t:=Trunc((C * 100) / ((h+1) * (w+1) * 8));
     // we get the average lightness in t

... now just check your ratio (change percent)

this works great for me :)
about 0-1% cpu usage on (pIII 550) 100 msec check intervals

Expert Comment

ID: 6484040
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LVL 14

Expert Comment

ID: 6485618
Lee_Nover, welcome to Experts Exchange.

I think it was not appropriate to make your post an answer because of the following:
* As I can see, your code does only detect whether motion was present, but not WHAT has moved. In many application it's important to detect WHAT has moved.
* Only post something as answer if you are "300% certain" that this is the one and only answer to the
question, and no other exuert has answered it already (maybe as comment).

Comments can be accepted as answer by the person which asked the initial question, so that you don't
have to be afraid of posting comments. If your comment is the one which answers the question best, you'll
get rewarded even though you did not post an answer. Comments do not lock the question for others, that's
why most experts choose to comment only so that other experts have a chance of seeing the question and post their opinions.

For more information, please read 
LVL 12

Expert Comment

ID: 6486712
well looking at the question (any algorithm for analysing pictures and reporting if any motion detected) ...

in the future i will post comments not answers

I just hope it does what zastava101 wanted

Expert Comment

ID: 6489572

Expert Comment

ID: 6499221

Expert Comment

ID: 6872423
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Expert Comment

ID: 7071432
Zero response, finalized.

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