I'm trying to create a function to implement border (frame) for images. in Matlab. So far I have been able to create a plain border around the image, but I would like to different shapes like a frame around the picture. A frame like this for example:

I am not supposed to use many functions from the image processing toolbox. I think I am supposed to do it basically by writing a code without the use of functions other than imread() and imshow().

Here's my code for the plain black frame:

Thanks!