Jailers are photographing tattoos (http://www.thesmokinggun.com/documents/crime/very-revealing-mug-shots-914205) for identification purposes.
QuoteMug shot sessions are becoming more revealing as jail personnel photograph a suspect's tattoos for identification purposes, a process that reveals and catalogs ink not normally visible.
In addition to getting fingerprinted and posing for head-on and profile images, arrestees may also have to remove or adjust their clothing so that their tattoos can be photographed.
And some of the people in the gallery look like <sarcasm> fine upstanding members of the master race. </sarcasm>