What does the cube that I image processed have to do with your interpretation of the letters you found? You posted it in such a way that it seems to imply support of your idea that John Dee signed this, but it does not.
There are letters in many of the images so I did some image processing on the folio you posted.
Here's what happened. If there's text in there (it looks like there might be but it's extremely small) it doesn't look anything like "John Dee" (regardless of whether it's viewed upside-down or rightside-up):
![[Image: F53rText.png]](http://voynichportal.com/wp-content/uploads/2016/10/F53rText.png)
There are letters in many of the images so I did some image processing on the folio you posted.
Here's what happened. If there's text in there (it looks like there might be but it's extremely small) it doesn't look anything like "John Dee" (regardless of whether it's viewed upside-down or rightside-up):