The "Signing of the Declaration of Independence" graphic is an adaptation of an image available from The Library of Congress (07/13/2006).  The copyright information for the original image is not clear.  The original image appears to be a digital conversion of a photograph by Theodor Horydczak of a painting by John Trumbull.  Interestingly, the subject matter of the painting isn't the signing of the Declaration of Independence; Theodore Horydczak misinterpreted the painting, and misnamed both the painting and the photograph.

The basic text of the Declaration of Independence, the high-resolution image of the actual document, and the high-resolution image of the William J. Stone engraving were obtained from The National Archives' "The Charters of Freedom" presentation (07/13/2006).