How to find a blob by color?
To be more precise, I'm trying to design an automated inspection system for a factory using a raspberry pi and simple cv. The system needs to detect defective parts in the line. They will pass through a conveyor belt and be photographed by a webcam. Mostly the parts are all dark, but we've instructed the personel here to put an adhesive sticker on the defective parts. They actually put it in an earlier manufacturing part, but the sticker is well visible on the final part and contrasts well with the dark hues of the parts. So what I want is to simply detect the colorful stickers within the dark, contrasting part. They're pretty much one color, e.g. all Yellow or all Blue, etc. So I'm looking for the simplest and fastest algorithm to detect a blob by a specific color. Although the stickers are all very round and maybe we could look for circles, there's a chance the sticker will be cut in the process, thus not being a circle anymore.
Any suggestions are greatly appreciated! Thanks in advance! Marcelo.