Enlarging the canvas using Preview

I wanted to create an image containing two other images of about the same size. Preview doesn’t have a tool for enlarging the canvas. I found this workaround on apple.stackexchange:

  1. Select all (cmd+A) and cut (cmd+X) the image from its canvas (convert to png if asked). 
  2. Resize the image as desired from the “Tools” menu (unlock the proportions if desired)
  3. Re-paste original image from the clipboard (cmd+V) and move it where you want it on the resized canvas
  4. Use cmd+- if necessary to zoom out (you’ll see checkerboard where the canvas is and white beyond)
  5. Paste in other images, etc, as you like