Image Flicker with USB IMAQ vision

[Edivad]

Hi Randall

I've just finished to redraw my vi's.

Now all the flicker effect are totally removed, and

the video result, is exactly what i want to obtain.

Your Diagram, was almost perfect, the only impreciness

regard the frame differencing. In fact if you compare 

the image difference module output result, you can 

note that, in your case the moving object isn't evident 

in the output, because the difference is performed, 

among two equals frame, while, i want to compute the 

difference among successive frame.

I've substantially modified the diagram. With some test,

i've noted that the canny filtering was totally useless

to the aim of better identify the object in the scene, 

so i removed it. Moreover i've added a control to the 

speed computing to compute speed only in the case that

there is only one object in the scene among successive 

frame.

I'm attaching the finally .llb of my vi, if you want

view the final result

Well at last the work is finished, i thank you very 

much for your support, thank to you i've learned a methodology 

to draw ordered diagram in Labview. Thank you very much again.

Davide 

[rpursley8 · Accepted solution]

You still have some issues with your block diagram.  You have three USB Grab functions running each time through your while loop.  That means that you have to acquire three images before you cycle through the loop again.  That means your are only processing the motion detection algorithm every third frame.  You only need one USB Grab since you are only using one camera.  In the vi that I attached, I do not perform the difference on the same frame.  I use two image references and write the new frame to them in an alternate fashion.  Also, especially in a case like this, do not use local variables for your image references.  You cannot be sure if the data that is being read into your motion detection algorithm is previous data or new data (or a combination).  Besides, it is not needed for this application.

I use a shift register to keep the previous reference for the image subtraction (i.e. image0 is a new frame, subtract from image1, pass image0 through shift register, image1 is a new frame, subtract from image0, pass image1 through shift register, image0 is a new frame, subtract from image1, pass image0 through shift register, etc.....)

When I remove the edge detection vis from the vi I posted, my output looks the same as yours but with a faster frame rate.  Attached is one final version.

[rpursley8]

By the way, this is a very interesting application.

[Edivad]

Great result, i'm seeing your vi and i must confirm your statement

sorry for my punctualization, i've derived some conclusion hastily.

For what concern my method for computing frame difference i can say 

that i saw this methodology in an example, and i was very trustfull 

to the correctness of the same. Your solution is surely more correct

and more performant. Now i'm going to analyze more carefully your 

diagram 

By the way, i've confirmed your 

second-last post as a solution of my thread. Thank you for the 

"very interesting application", this is a project that i've thinked 

to develop for a subject at university.

Thank you very much for your interest

See you

Davide

[Nitoruiz]

Hi.

Is there any chance that you could send me this code for labview 8.5?

Thanks in advance.

Vinicius.

[NIquist]

That thread is a couple years old so they may not still be around.  Save the file and post it to the downconvert thread and someone will get to it.

http://forums.ni.com/t5/LabVIEW/Downconvert-VI-Requests/td-p/1067229

[Nitoruiz]

Ok.

Thanks NIquist. I added the files there.

[shifali]

hello  

we are doing a project on vehicle tracking using lab view 

i have completed the following steps

1)color to grayscale conversion

2)threshilding

3)morphological operations

my problem is that how do i get a bounding box around the vehicle and track the vehicle?

please help.

an immediste reply would be of great help to us.

thank you

[NIquist]

You are posting an unrelated question on an old, SOLVED thread.  If you want some response you should start your own new thread so that it will be noticed.