Finding The Centre Of An Image In Photoshop

Quite often it is necessary to find the exact central point of an image.
There are a couple of ways of achieving this in Photoshop.

Approach #1
Open any image.
We are going to use guides and they only work when the Rulers are on an image.
Put the Rulers on the image with Ctrl + R / Cmd + R. Guides will snap to the centre of an image but it is a bit subtle.

To make the job easier, we’ll convert the Ruler measurements to percentage figures.
Right + click / Control + click one of the Ruler bars.
From the pop-up menu, choose percent.
Drag the cursor down from the top Ruler bar to create a new guide.
Drag it down to the 50% mark. It will snap into place.
Drag the cursor right from the vertical Ruler and move it to the 50% mark. It will snap into place.
Where they cross is the exact centre of the image.

Approach #2
The Transform tool has a centre mark in it.
Open an image.
The Transform function only works on a layer and not on a locked Background.
Using the Layers panel, hold Alt and double-click on the Background icon or label.
Bring the Rulers into view with Ctrl + R / Cmd + R.
Open Free Transform with Edit > Free Transform - Ctrl + T / Cmd + T.
Drag a guide down from the horizontal Ruler until it snaps on to the central point of the Transform.
Drag a guide to the right from the vertical Ruler until it snaps on to the central point of the Transform.
Remove the Transform with Ctrl + full stop / Cmd + full stop or use the Esc key.

Note: Copy an object from one image and paste it into another and it will automatically be pasted into the middle of the image.