What you are describing is a general computer vision algorithm that is not covered by our sdk. However with our upcoming SDK release 5.0, through our Plugins API you can integrate your own custom algorithm into our environment and use it in your application.
We currently develop applications using Ionic with Cordova/PhoneGap and have used the Wikitude plugin succesfully on another project. I'm trying to work out a way of doing colour detection on the camera stream from the user's camera and then replace certain colours (or overaly) with another colour or even a repeating image. A good example of this is the Dulux Visualiser.
I was wondering if there is a way of doing colour detection through Wikitude - is the API open enough to allow this. If not, does anyone have another solution? I'm looking into using http://trackingjs.com/ library, but it would require getting the camera feed as a canvas element in the WebView, which I'm struggling to achieve.