Colour ... Wizard Of Oz

I looked at how the Wizard of Oz begins in black and white then changes into colour when she opens the door of her house in Oz. I think the use of using Black and white footage at the beginning of the film connotes that her life is dull, boring and possibly repetitive (she never moves away or leaves the farm she lives on). When she is taken to Oz the colour is very saturated and almost unreal ... this is to connote fantasy and adventure! She has gone beyond her boring life to somewhere new, fresh and exciting.