To have the user upload an image for their own pass requires some custom work and can't be done straight from the Pass Designer. This requires a custom form and the PassKit API.
Your tech team will need to create a custom form (which contains fields that the customer needs to complete) and a 'choose file' button for the image. This will then upload the image to our servers, then add it to the pass when it is created - which is all done via the API. Please click here for more information on our API Documentation.