Advertisments - Emphasis of color

In this series of posters, Dior was clever in using color.
They jumped out from using black/dull color as background to emphasize the product, but try to use only one hue in the whole poster, including the background, even the Dior Icon were same color as the garment.
This is the "Emphasis of color". Designer made the background reflecting light at different angles, resulting hues with different tones/ saturations. Therefore the background color(s) will not be too close with the subject, this can make audiences more focus on the product.