Getting a picture printed on canvas can be expensive, and the results are not always what you might have hoped for. A less expensive option is to take a poster; either ready-made or one you've have printed, and coat it with an acrylic gel medium to give it texture. You will be painting the gel medium directly on the poster, so the texture of the brushstrokes will make the surface three-dimensional.
Things You'll Need
Acrylic gel medium
Particle board, MDF or other stiff backing
Spray adhesive on particle board or other stiff backing on which you will mount your poster. Lay the poster, printed side up, on the board and smooth it down from the middle out toward the edges.
Cut around the edges of the poster to remove an excess border that you don't want to include in your finished work. Use a straight-edge to guide your cutting tool if necessary.
Add acrylic gel medium to the face of your poster. Use a paintbrush to create brush stokes. For a natural look, make the brush strokes correspond to the lines of the picture.
Let the poster dry. The gel will dry clear, so how much you use will depend on how thick you want the texture. You can always add more later.
As an alternative to brush strokes, use a piece of canvas to press texture into the gel.