How do I write a program that "talks" to a webcam and tells it when to take a photo?

[dearbear]

I need to write a program in C (on Linux) that tells a webcam when to take a photo. Can anyone give me some resources or tips for how to get started with this? I don't really know how to go about doing this.

I am using a Logitech webcam, so I looked at their website, and they suggest I use DirectShow, but that seems to be available only for Windows. Like I said, a few nudges in the right direction would be greatly appreciated. Thanks.

[Kennedy]

Open source is . . . well, open. So, let me search that on google for you.