[R] How to flip image?

[Ernie Adorio]

I am displaying some image of a person's head stored as a matrix, using 

  image(Face, col=gray((0:255)/255))

but the image is flipped, the nose is above the eyes. How can I 
correct  this without  making changes to the matrix Face?
If not possible, is there any built-in R command to reverse the rows of a 
matrix?

Ernie Adorio
Math Department
U.P. Diliman