In Java , Exclude a string while encode using base64

问题

Is there a way that I can exclude particular string (II*) while encode a tiff file and keep that String as it is and also during the decode ?

Or

How can I specify the encoding to always encode (II*) as three characters and not to combine with any other characters ?

Below code to replace the string II* with ( II* ), however tiff got corrupted after that.

           Path path = Paths.get("D:\\Users\\Vinoth\\workspace\\Testing\\Testing.tiff");
            Charset charset = StandardCharsets.UTF_8;

            String content = new String(Files.readAllBytes(path), charset);
            content = content.replace("II*", "  II  ");
            content = content.replace("  II  ","  II*  ");
            Files.write(path, content.getBytes(charset));

来源：https://stackoverflow.com/questions/38431971/in-java-exclude-a-string-while-encode-using-base64