There is no question of warranty getting void. Sai Colorium did a fantastic job on my Linea. The colour-matching was 100% perfect. Khan of Sai Colorium told me that they feed the car's manufacturer/brand/model/version/shade, etc., to their computer and it recommends the proportions of various colours of paints to arrive at the particular shade. It is similar to Asian Paints computerised system that I had seen in a hardware shop while buying Asian Paints for painting of my house. The shop owner mixed various paints at the proportion indicated by the system to arrive at a particular shade chosen by me.