Yeah, like I explained you CAN use an image from a docker daemon if you WANT to:

    trufflehog docker --image docker://new_image:tag

If you don't want to scan from a docker daemon then, you can pull from docker hub:

    trufflehog docker --image trufflesecurity/secrets 

or from a tarball:

    trufflehog docker --image file://path_to_image.tar