Put some background pixel into top and bottom of a image

I have a image like this and I want to put some background pixels to top and bottom of the image. How to do this??

Answer 1

[Image Analyst]

Expand the canvass with padarray(). Then use copy and paste, like my attached demo.

[Malan Jayanka]

Expand the canvass with padarray() mena this?

And also this code is work only for gray scale images??how to do this with RGB images??

[Image Analyst]

The newly attached version also handles color and indexed images.