Yes! The Wizard of Oz was filmed that way to give it the "Over the Rainbow" effect. The Black and White parts were actually filmed on Sepia Tone film, It has a more brownish tint to it. Which if you have the DVD you will see the true color of the Sepia Tone. The color parts of the movie were filmed on 3 strip Technicolor film. It was extremely expensive back then but they decided to do it right. The Wizard Of Oz was NOT the first color movie, there were quite a few others before. Where the black and white turns to color those few frames on the film were hand painted to give the transition a smooth effect (where Dorothy is looking out of the house door). So to sum this up, The Wizard Of Oz was purposly filmed that way, and was never changed. Some people thought it was later "colored" in. Which it wasn't, even this day and age that is nearly impossible*. Also the 3 strip technicolor film offered the apsolute best rich color and resolution. Today we use a single strip which isn't nearly as good of quality, but it is cheaper and more economical. When I say 3 strip technicolor, that is for Red, Green, Blue. 3 diffrent films running through the camera at the same time. The cameras were loud, large and expensive for that time.

* When I said nearly impossible I mean to have it look as colorful as the Wizard Of Oz is. I beleive Ted Turner had some movies "colorized", but they are no wheres near the comparason of a true color film. Computers are pretty good at colorizing, however they still can't seem to give it the right depth and effect to make it look as though it was filmed in color. So generally speaking, with the technology available I think it is safe to say it would be nearly impossible to colorize a Black & White film and give it the true rich color that is seen in The Wizard Of Oz.