The spell is recited while the witch, the victim and the painting are all inside the drawn fay circle. Once the recitation and dance is completed, the victim is sucked into the painting, becoming a character on the image itself. As long as they are imprisoned within the painting they cannot interact with the outside world in any way. Other individuals who are painted are just statues to the imprisoned victim. However, other victims who have been imprisoned in the same painting can be interacted with.
Anyone observing the painting get a feeling that something is wrong with it, but can't figure out what. If it's studied meticulously one can notice that sometimes one or more people in the painting change places from time to time.