A digital image is processed to hide information, by generally inconspicuous adjustments of pixel values. Prior to initiating the \u201creal time\u201d synthesis process, a database is created of all possible triphone contexts by inputting a continuous stream of speech. A reconstructed image of the imaging region is computed from the acquired echo data 104, and the reconstructed image is then be stored andor displayed on a display monitor 106. An apparatus can include a lamp and fixture with a visor length that is shorter than most conventional spill and glare control visors. Then, the time for forming an image includes a plurality of frame periods . The present invention also provides the NOx trap composition used in the method.