To view an image, click on the appropriate link (after noting the size and inferring its potential Internet transfer time). In most web browsers, to download the same file for local use, right-click on the same link and choose "Save Link As..." or a similar command. In general, the "full size" images are most suited for downloading and closer analysis; the screen width images are intended only for Internet access.
Sizes are given for full size images for purposes of comparison between the different image formats. The sizes of screen width images, however, are given only to allow network transfer time to be estimated. These sizes are given in parentheses.
Original 8-bit Grayscale, No Contrast Stretch
|Screen width as an interlaced GIF||(17 KB)||
|Full size as a grayscale TIFF||8231 KB|
All of the images below have been contrast stretched. Without this, some of the originals are extremely dark and of low contrast. To get an accurate sense of the inherent difficulty in imaging some of these pages, it is important to have a look at the original.
Three different JPEG compression levels are shown in the next three tables. The precise meaning (or even the name) of the parameter "quality level" is specific to a given piece of JPEG software; it has no absolute meaning, but is a relative measure of how highly compressed an image is. Compression ratio is the only useful absolute measure.
Several screen width viewing copies of the "quality level" = 50 JPEG file have been prepared for presentation here.
The full size JPEG is in sequential JPEG form as are all the Phase II production images. A means exists to convert a sequential to a progressive JPEG losslessly, provided both are the same size. This was not done here, since the purpose of the full size image is to permit close inspection of the final resolution image. While it is a slow process, sequential display (or downloading) is better for this purpose.
JPEG "Quality Level" = 50
|Compression ratio:||50.8 to 1||
|Screen width as a progressive JPEG||(11 KB)|
|Screen width as a sequential JPEG||(9 KB)|
|Full size as a sequential JPEG||162 KB|
No thumbnails or screen width images are provided for the following two JPEG files, since they would be indistinguishable from the set just above.
JPEG "Quality Level" = 40
|Compression ratio:||45.2 to 1|
|Full size as a sequential JPEG||182 KB|
JPEG "Quality Level" = 30
|Compression ratio:||37 to 1|
|Full size as a sequential JPEG||222 KB|
Binarized, 1-Bit per Pixel
|Screen width as a "scale to gray" (anti-aliased), interlaced GIF||(9 KB)||
|Full size as a Group 4 compressed binary TIFF||13 KB|
|Full size as a two color binary GIF||33 KB|
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