Transferring photo from iPhone to computer ?

Simplest way? 

Send an email to the PC adding the photo as an attachment. The iPhone will give you the choice of photo resolution, always choose “Original” to preserve the full resolution. A single photo in a single email will not normally breach the file size limit.

Just unlock the phone and connect it with the USB cable.

If itunes starts, close that.

If the phone asks to trust the computer, OK it, wait a minute then disconnect and re-connect the phone. (And close itunes again).

Go to Computer or File explorer etc., look down the left column and you should see the phone listed somewhere in there, just like a USB drive.

In there, it will have a DCIM folder - that's where the photos are, just like any digital camera.

They are likely grouped in folders.

You can view them and copy them as you like.

Make sure the phone stays unlocked until everything shows up, which can take some time.

The folders in the phone item may not appear instantly, give it a minute or two, or right-click and refresh it if nothing happens.