Roll and Implode Frame

  

The above frames were created by manipulating a regular frame at IM using roll and implode.

First I took this frame to Image Magick Studio.

Click on Transform. In the box enter the parameters for half of the width and half of the height, preceded by plus signs. This frame was 300x300, so I entered +150+150. Click roll and transform.

Next click on FX. Enter 0.5 in the parameter box and click implode (for the frame on the left). Enter -0.5 for the frame on the right.

The images should appear as below at this point.

Go back to transform and roll again at the same parameters as before. The results are below.

You can experiment with the implode values or just roll the width (+150+0) or the height (+0+150), so that only the sides or the top and bottom are curved.