Scan a book or photos. I scanned at 300 dpi, but you can scan at 600 dpi too so that you can blow up the picture.
Print out the images of your choice and trim them to fit the canvases. If inkjet, spray with clear acrylic sealer or hairspray on both sides and let dry before trimming.
Paint the canvases with the colors of your choice and let dry.
Spread a medium layer of Mod Podge down on the canvas and smooth the design down to the top. Let dry for 15 - 20 minutes.
Put a top coat on the image and then the entire canvas. Let dry completely before hanging.
Notes
If you are having a hard time smoothing the image to canvas, turn over on a non-stick work surface and smooth from the inside. This helps since canvas is flexible.