(Work on just pan/tilt footage with the object fixed on position) i.e. object still but just camera move
In PS:
-Open PS with the original image
-Drag and Line up the background stock image to fit the original (foreground) image, a new layer will be created → Drop its opacity to 50% to check if the fit is ok
-Use Quick Selection tool W) to select the area want to composite (reduce brush size for edge area selection, hold Alt to remove unwanted selection) → Add layer mask
On the created Layer Mask →Use Brush tool to modify the edge of blending area (Black box on top means paint out the mask don’t want, white box means paint back in)
On modified Layer Mask → Ctrl+L click → Add adjustment layer → On adjustment layer, add Hue/Saturation layer → Tune the color
-Cut out the unwanted background, Save the key out image by tick Alpha channels
In AE
8:00 to 10:15
-Track Camera on the footage (start analyze) → Advanced → Solve Method: Tripod Pan, Tick Detail Analysis (In 3d Camera Tracker setting) → If happy with the trackers shown on screen → Create Camera
Better way: Select tracker points wanted (a disc is formed on screen) → R click, Create Null
So a Null layer above 3D Tracker Camera layer above footage layer
-Drag the composite photo on top of all layers → Turn on 3d effect cube → Parent the photo layer to the Null layer
-To make the edge of photo blend/assimilate to the footage
Duplicate the footage and put on top of photo layer → Add Luma Key → Key Type: Key Out Brighter → Adjust Threshold until the edge part hide behind the footage → Mask the part where don’t want the photo hide behind the footage