Render Shadow on Background Image Wall

[saddyrock]

I would like to place the 3d Object - a framed painting - on a wall in the "Image as Background." Placing the object can be accomplished but I can't figure out how to get the shadow of the object on the wall of the background! Driving me nuts. I made a plane but that shows up in the PSD render and there's no way to get rid of it and still keep the shadows.

[Ussnorway]

to make shadow you need light and the type of light I would use here is sunlight in a downward dirrection from about there that roof light is placed in the image

[saddyrock]

Thanks for your response, Ussnorway. I do use light but, when rendered, the shadow appears on the "floor" and not the wall in the background image. See this render and the arrow points to the shadow. 

[Ares Hovhannesyan · Accepted solution]

What I have get is the shadow on the back plane when use 3 point lights. See attachment. Did you try it. Finnally you can also use photoshop to add shadow effect behind picture (selection).

[saddyrock]

I did try the plane but then I couldn't get rid of the plane in Photoshop as you can see in the first photo I uploaded. The Photoshop solution seems to be the best. I placed a new layer under the painting then added a dropshadow and that seems to be the best option. Thank you for your help!