We don't know of a product that converts graphic files between Apple II and Macintosh formats. This type of conversion is one of the most difficult, as the files are usually stored as an approximation of the hardware's display capabilities, which vary greatly between different computer lines.
Though we couldn't find a product that will do this, what you're probably looking for is a utility that will convert a file into a "standard format," such as Graphic Interchange Format (GIF). Once in this format, you could move it to the Macintosh and re-translate it.