Hello seems like a good idea. I will let you know here because it's very simple, I've tried it once and worked perfectly.
Create a Hue/Saturation adjustment layer and bring the saturation to -100, duplicate this layer and convert the blending mode to screen, keep duplicating the screen layer until your dress turns white; this depends on its original colour. Remember to mask all layers to the layer of the dress.
I hope I helped! Let me know if you faced any problems concerning this.