Following this interesting link Project 6 beep boop bop a love story. I found another way to integrate images generated in Blender and real images. The process is very fluid and effective. so much so that the author of this Blog so used to a very good animation.
The process is very similar to that described in the entry Integracion de imagen real con imagenes. Change is in the manner intengran leftovers and the actual image. This mask is used for shadows and so this does not affect picture quality. Being the end result of very good quality.
As always comments and suggestions are most welcome.
In my blog describes the process of creating this image and displays the nodes and materials.