Thank you for the advices. in my application the target are bubbles, they are circles but slightly deformed in shape also. Some comes in elliptical shape also; some are over lapped also, this is a new information that convolution but is it like cross-correlation? i have tried that but it is not suitable if the objects are of different scale. if any one can give an idea i have a plan to make a new algorithm also. i am looking for ideas; i have some but i want to discuss it with u people YOurs SaRIn.... On Mon, May 17, 2010 at 10:21 PM, Marcel Birthelmer wrote: > On Mon, May 17, 2010 at 6:47 PM, Olin Lathrop > wrote: > > Marcel Birthelmer wrote: > >> One way of detecting symmetric objects is convolution. > > > > There is no need for objects to be symmetric to detect their signature > with > > convolution. It does, however, alleviate orientation issues. > > > > > > If you don't know the shape of the object, but you do know that it's > symmetric (which, granted, is not the case in this scenario), you can > still use convolution. This is useful for example when detecting > street signs in automotive vision applications, since pretty much all > signs are symmetric in shape. > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist