The superheterodyne radio receiver is one of the most popular receivers used in a broad range of radio communication systems, from broadcast to high performance two way radio,to stationary and mobile radios. An important specification of the superheterodyne radio is its image rejection. In order to understand the image rejection challenge one has to understand the basis of the image frequency. A paper released by SIgnal Processing Group Inc., and available on the SPG website is an attempt to explain this specification and its ramifications. Interested readers may access the paper under the free items link on the SPG website.