It's rather easy to use JSecureImage;

• Add jsecureimage.jar into your build path and then add a code piece like the one below;

import org.webguvenligi.jsecureimage.*;
...

try{
  // call the static method with directory, file name and image type
  JSecureImage.isValidImage("my_upload_directory", "uploaded_image.gif", "gif");
}
catch(JSecureImageException jsie){
  // invalid image
  // jsie.getMessage for detail exception message  
}

// valid image