Python camera movement detection...

[7e7en]

Hm.. I'm thinking of starting a project in Python a little something like this: Sentry Gun

But it will take input from a camera, (Possibly threshold it) and then the frame after (Threshold again) then compare the two frames (Which is why possible threshold for easier comparison) and if there is a major difference, I.E someone is now in-front of the camera, it will do something.

Not too sure how I'm going to do this.... Any idea?

 

[7e7en]

Without meaning to sound like a ****, learn how to do your own research, specifically - how to use Google:

http://negativeacknowledge.com/2010/06/automated-nerf-turret/

It's all very well asking specific questions on forums if you're having a problem and can't find any material about it, but questions like "Not too sure how I'm going to do this.... Any idea?" just strike me as lazy.

Here endeth the lecture

I've started doing a load this morning. Got the camera to take images and save them, just need to find a way to do a comparison on both. But thanks anyway, I was mostly asking if people had any ideas that would make this easier or whatever.

 

[7e7en]

Ok, I just set up a script that will check the two histrograms and look for a large difference.

Thanks for all the tips, I'll probably have the image split up into 4 and check each one to be more specific on where the movement is coming from.

 

[7e7en]

Going a bit further, why not be able to adjust the sensitivity? So say if you increase the sensitivity, your grid becomes smaller... maybe a 4x4...all the way up to say 1000x1000 - then you can adjust the percentage of grid areas required to show changes.

I think by being rigid with your grid sizes you may come up against problems with subtle changes.

Further, you may want to say, only look for changes in certain areas of the image - so look only at a pathway, not the trees and shrubbery around it - so you may want the ability to flag only certain areas of theimage.

Hm.. well there is only 76800 pixels(320x240) but if I can split the image up by 4x4 I could easily make it larger and more precise. I've also look and some servo controllers and some other things, that should be very easy to use once this part is finished.

 

[7e7en]

Ok, I switched it to greyscale and set it up to split into a 4x4 grid (Can easily be made larger, but for now it's 4x4) then when there is motion in one of the 4 squares I want it to be filled red, so when the grid is say 32x32 it will show whatever is moving covered in red pretty well. I.E:

Anyone know the best way to add a colour (Red) onto a greyscale image with python, had a look around but can't find anything to work.

Also once I figure out how to do add the red it will be pretty simple and will just take me a little while to put it all together and it should work quite well.

 

[7e7en]

You can process in grayscale, but you don't necessarily need to display it in grayscale as well. You can just take a copy of the captured frame, and work with that, and using the result of the processing you can alter the colour image that needs to be displayed.

How have you converted the image to grayscale, and what sort of object is the grayscale object? i.e. is it still an RGB image or is it an actual grayscale image object?

Using PIL (Python Image Library).

img = Image.open('image1.jpg')
img = ImageOps.grayscale(img)
img.save('image1.jpg', 'JPEG')

That opens the image converts it to a grayscale one, then saves it. So I'm guessing it is actual grayscale not RGB.


Quick Update:

It can now detect move in the top left corner. Soon to be top right/bottom left/ bottom right. Then I can hopefuly divide it up some more.

 

[7e7en]

Just installed Python to give this image conversion stuff a bash

Once you've got your grayscale image, you can convert it back into RGB colourspace (but still remain gray) with:

rgb_img = img.convert("RGB")

If you display a value of a pixel, you will get a tuple of three values which are all the same indicating it is gray:

img.getpixel((1,1))
(81, 81, 81)

Now if you want to shade an area of the image red, all you do is take the value of the pixel and set it to the same value in all channels but with the red channel set to something like 200.

Alternatively, you could try modifying a second image of the same dimension and add your red regions, then blend the two images together using blend method, which might get a nicer blended red effect with the background.

Thanks, I got a red image and blended it, which then turned it blue, so changed the red image to blue and turned the alpha to about 3. Got this:

Seems to work, now just a hell of a lot of testing and I'll see if I can get this working!