<Ul> <Li> an image that is not rectangular can be filled to the required rectangle using transparent surroundings; the image can even have holes (e.g. be ring - shaped) </Li> <Li> in a run of text, a special symbol for which an image is used because it is not available in the character set, can be given a transparent background, resulting in a matching background . </Li> </Ul> <Li> an image that is not rectangular can be filled to the required rectangle using transparent surroundings; the image can even have holes (e.g. be ring - shaped) </Li> <Li> in a run of text, a special symbol for which an image is used because it is not available in the character set, can be given a transparent background, resulting in a matching background . </Li> <P> The transparent color should be chosen carefully, to avoid items that just happen to be the same color vanishing . </P>

What is the best image format for transparent background