1. Color is unperceivable to the touch.

2. Steganograhy is to embed unperceivable data in Medias of images, audio or video.

3. However, love is unperceivable. You can only know what love is when it's understood and translated.

4. By this approach, we enhanced the unperceivable property as well as robustness.

5. However, scientists find that when people hear the name of the object in the question, these unperceivable visual images can become perceivable.

6. One quick way to solve this problem is to use fast digital servos to make the motion differential unperceivable .