How can I modify this picture to make it seem like the pizza is shown from above?
You can't change the actual viewing angle of a 2D photograph in Photoshop. It's not possible.
You could only distort the image by stretching it, but it wouldn't be a true top view. At a push, you could try to remove the distortion using the Liquify filter, but ultimately it would be better to take photos of the pizza from different angles.
An example: Image stretched vertically (left). Removed distortion using the Liquify filter (right)
What I did here was use the Liquify filter's Forward Warp tool, to move the centre of the cuts into the middle, and using the same tool set to a smaller size, I also thinned the crust and board by moving them a little at a time. There's still a little stretchy distortion around the top edge, which could also be removed similarly if you have more time.
You'd need to recreate details that would be revealed if the photo was taken from a different angle (and hide some others). There are already some AI applications that can guess those missing details, but probably not yet for 3D transformations applications...
However, if you'd like to do that manually anyway, here's a very rough plan:
- Correct the perspective of the main object.
- Add non-existing details by reusing those already existing, that look similar, making sure that the lighting is correct.
- Remove any unwanted details or squash those that would take much less space in the new view.
- Correct any perspective-related issues at the detail level.