hi, im trying to learn how to do a nice little trick

i need to make the transparent part of a photo embedded in a webpage change colour with a slider or a colour chart of some kind.

does anyone know what research i need to look at in order to learn this.

or if anyone has an easier or better what of doing this i would be most grateful

here is a site with what im looking for

http://www.loveglassuk.com/Colour-Designer.aspx

thank you