You ll probably need to apply some shadows in the corners to make it more realistic.
Surface blur photoshop to clean up floor.
That being said go to filters blur surface blur and when the window pops up change the radius to somewhere around 9 and the threshold to 27.
Automatic camera shake reduction takes into account the blur trace for just the default region of the image that photoshop has determined as most suitable for blur estimation.
It allows photographers to touch up their photos graphic designers to create images and facebook meme lovers to design their own internet sensations.
Then select a radius of 15 30 pixels depending on the amount of dirt and grime on the background.
Which as you can guess dodge and burn frequency separation and other techniques used by high.
As suggested in the comments you got find a similar floor and add it with the right perspective and shadow in photoshop.
Select the refine edge brush tool on the left side of the workspace.
There are a zillion buttons to push and.
In the preview window make sure the dirt completely vanishes but.
Then drag over the edge of the subject to clean up the mask edge.
Photoshop is a great program to use for just about everything.
Stamp a new merged layer shift cmd ctrl opt alt e and select the gaussian blur radius according to how much you want to smooth out the surrounding background.
In this case i ve used a radius of 80.
Don t forget to add the same noise to this layer using the steps as before.
The extensive selections of tools in photoshop can be daunting for novice users.
Being used to cleaning skin with dodge and burn for beauty i tend to do the same with weddings.
Just stick a new floor.
Click filter noise median.
To further fine tune the image you can have photoshop compute and consider blur traces for multiple regions.
A very basic and quick overview of using surface blur and smart sharpen to clean up the quality of gifs for tumblr.