Re: Comparing images and producing co-ordinates

James <[EMAIL PROTECTED]> wrote:
> I'm looking for free software that will allow me to take 2 images from
> a web cam and recognise the differences between them.
> For example in one image an LED would be off and in the next it will
> be illuminated. Is there any software that will be able to recognise
> such a difference - and produce coordinates to locate the item (in
> this case the LED)?

> I'm new to this kind of thing so it needs to be pretty simple!
> I've been told that certain image formats are better for this kind of
> processing. I'm not sure what they are and searching the internet
> hasn't produced any results.

I suppose you have an RGB image. Then calculate the difference image
for each color chanel. If you further know the color or the difference,
maybe approximately, you can extract the pixels of interest.
Maybe you need morphological filters or a median filter for erasing
pertubations. If your remaining object  is a circle (LED) you
just have to calculate the center of gravity (sum seperate over
x- and y-coordinates and normalize by the number of pixels of
your object)...

Greetings, Uwe

-- 
Dr. rer. nat. Uwe Schmitt   http://www.procoders.net                      
[EMAIL PROTECTED]      "A service to open source is a service to mankind."