The BSD license does not contain a definition of what is meant by "source form" and what by "binary form", although it does make the assumption that the "source form" can include the license text directly.
As "source form" and "binary form" are also not defined in any relevant laws, it essentially boils down to using common sense in determining if something is "source form", "binary form" or not covered at all by the BSD license.
Copyright law does not distinguish which forms of copyright license can be applied to which kinds of works, so there is nothing in the law stopping the BSD license from being applicable to the images. The only other case where the images would not be under the BSD license is when the license documentation of the project explicitly mentions that the images are under a different license.
Given the nature of most image file formats, it is reasonable to treat images as being in binary form.
Printing the image is a transformation onto a different medium, which is allowed under the BSD license but you still have to comply with the license terms of the BSD license.