Mise-en-scene is a French word meaning "putting into the scene." It refers to the way a director arranges the visual components in the frame of the shot. The main elements of mise-en-scene are the sets, costumes, lighting, color and actor's performance. The chief members responsible for the manipulation of objects in the shot are the director, cinematographer and production designer.
One aspect of mise-en-scene which signified a change in time during the beginning of the 1939 masterpiece, "The Wizard of Oz," is noted in the first 1/2 hour of the film when everything is filmed in black and white, colored in a unique sepia tone process. The opening and closing credits, as well as the Kansas sequences, were designed to distinguish the extreme differences between Kansas and Oz. Every scene which takes place in Kansas was filmed in black and white. The grass in the farmhouses garden was dry from the burning heat of the sun, the coat of paint on the house had turned to a fading gray and Aunt Em and Uncle Henry were 'gray with age'. The setting in Kansas was another way to imply how dull life was at the farmhouse and to emphasize Dorothy's solitude.
The cinematographer, Harold Rosson, wanted to make the distinction clear that Kansas and Oz were from two very different worlds. For the sequences based in Kansas, he emphasized on the realism of it to make it more dull and boring to create a world any teenager wouldn't be satisfied with. As soon as Dorothy lands in Oz, everything is in Technicolor and everything is painted with bright colours to signify the joyousness that Munchkin Land had to offer. The total change in space here helps bring the audience out of a gloomy state that life in Kansas gave them, and replace it with a fresh clear mindset of what Oz can offer them.
The supporting characters in "The Wizard of Oz" do change throughout the film but the supporting character I'd like to focus on is Scarecrow.