Is there a converter from composite or s-video to component video?

There are many converters on the market, from a few dollars to many thousands of dollars for a studio quality decoder. There is a limited benefit in using a dedicated composite to component decoder: Once a signal has been encoded into a composite or an S-video signal, some of the picture detail is lost forever. Decoding the signal into component does not restore the quality.

Bear in mind that every television that has a composite or S-video input has a decoder to obtain a component signal. Using an external decoder simply moves the process to another point in the signal path. Having said that, a good quality decoder may give better results than a television's internal decoder.