how can i write a matlab programme that exracte keypoints (points of interest ) from an image ?

i want to write a matlab programme that exracte keypoints (points of interest ) from an image, but i don't have the basics, i mean the theorie and the maths, means that i'm a bigginer :p so pleaz can anyone guide me ! where can i start ?

[Geoff Hayes]

Houssam - please clarify what you mean by points of interest. Do you want the user to pick out objects from the image or do you want some automated code to pick out the objects for you? You need to provide more details.

[Houssam]

Well i've been doing a lot of reaserch about it and i found a lot of algorithmes to do it such as Harris, SURF SIFT ... but my goal is, like you sad, is to automatically detecte specefic objects from an image using keypoints (corners, eadges ...) !!