The colours of soap bubbles and soap films is a result of so-called interference of the light reflected from (and in some special cases transmitted through) the soap film. In photos below we have tried to optimized the illumination conditions to enhance the colours, for example by using a light table. Here we are using a white light source containing all colours.
NB: Click on the images to see them i full size.
See also our photos of soap bubbles illuminate by a single colour light source (so-called monochrome light).