Color registration was done from the scanned high resolution files available from the Library of Congress server (16 bit black and white tiff files, approximately 70 Mb each, image width and height about 3800 by 9500 pixels.) The resulting color files: 48 bit tiff files, approximately 70 Mb each, image width and height 3800 x 3200 pixels. No image editing was applied to registered images (in particular, there was no color correction and no removal of any image defects).