Sony Xray cameras

SXIR is the technology, which allows spy equipment such as the Sony Nightshot Xray filter, or xray cameras to see through clothes, dark windows and sunglasses as well as detecting forged documents.

SXIR technology has been adapted and marketed as xray cameras , x-ray vision, and infrared pass filters. Unlike the x-Ray Glasses you probably saw advertised in the back of comic books however, this technology really does see through many types of clothing. They are ideal for law enforcement officers, security personnel and other surveillance such as looking for hidden objects, without being too intrusive.

The way it works is rather simple really. Many types of clothing allow light and infrared light to pass through the fabric. This light is reflected back through the clothing, off the skin, to our naked eyes. What we normally see is both the reflected normal light (off the clothing and the skin underneath) mixed with the Infrared light (off the skin). The lens filters the normal light out, leaving only the Infrared light and some other ambient light waves. The effect is , the clothing looks something like glass.
Not all clothing allows xray camera IR light to pass through. The clothing, which works best with these IR filters, is Silks, swimwear (most swimwear is designed to allow some UV light to pass through to help with tan lines, and in doing so, allows the IR to pass through as well), and most types of synthetic material.

Since it is IR and not xray vision (which is good, because who wants to look at bones?), what you see is in color.