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Digital Petrographic Slide Collection
The thin section photomicrographs in the Digital Petrographic Slide Collection originated from Howard Wilshire and William Phinney.Howard Wilshire (USGS) was involved in astronaut training for Apollos 14-17 and was on the Preliminary Examination and Field Geology Teams. During this time he photographed many hundreds of lunar sample thin sections. Wilshire documented the slides with annotations directly on the slide mounts. In an effort to make this valuable slide collection readily accessible the Northwestern University Center for Planetary Sciences (CPS) scanned over 6000 slides and transcribed the annotations that form the basis of the searchable database.
William Phinney contributed 315 additional slides from Apollo missions 11, 12, 14, 15, and 17. Phinney was the Chief of the Geology Branch at Johnson Space Center and former Associate Curator for Lunar Samples. He was involved with the geological training of Apollo astronauts and the preliminary examination of samples.
Acknowledgements: Scanning was done by Sarah Braden, Joe Eckart, and Nick Seltzer. Joe Digilio, Emerson Speyerer, and Mark Robinson designed and implemented the web interface and Paul Spudis (Applied Physics Lab), Brad Jolliff (Washington University), and Gary Lofgren (Johnson Space Center) provided petrologic guidance. Finally Howard Wilshire helped interpret slide annotations. The originals are archived with the USGS Branch of Astrogeology in Flagstaff AZ, and were generously loaned to the CPS for scanning (thanks to L. Gaddis).
Description of Slide Scanning Process
Scanner: Nikon Super Coolscan 4000 ED with a Nikon SF-200 Slide Feeder attachment
Software: Nikon Scan 4
Scanner Settings:
For the Kodachrome slides the scan type was Kodachrome
For the Ektachrome slides the scan type was set to "Positive"
Color setting: "Calibrated RGB"
Scan size: 3469 pixels by 2367 pixels
File Size: 47 Mbytes
Analog Gain: Neutral
Digital ROC: Neutral
Digital GEM: Neutral
Digital ICE: Off
MultiSample Scanning: 8x
Bit Depth: 14 bits per color
Resolution: 2400 pixels/inch
File Format: 48 bit TIFF
Frequent jamming in the SF-200 auto feed mechanism occurred with both
Kodachrome and Ektachrome slides. After experimentation we found that slides
were much less likely to jam when placed in the scanner backwards (the beveled
edges of the slide mounts caught on the feed mechanism of the scanner when
oriented "correctly").
We compared scans of the same slide acquired both backwards and forwards and we
found them to be statistically identical.
Post processing of the slide scans included (Photoshop 7):
Orientating the images correctly
Converting color from 48 bit depth to 24 bit depth (14 bit per color to 8 bit per color)
Reformating the images into .png and .jpeg files
Resizing the images into 100% (2400 pixels), 50% (1700 pixels), 25% (1200 pixels), and thumbnail
sizes for .jpeg (400 pixels) and .png (100 pixels)
Color correction was applied with a histogram based stretch,
for each band the lower 0.1% dn values were set to 0 and the upper 0.1% were set
to 255.
The original unmodified 48-bit TIFF format scans are available at the bottom of each indiviual slide page.
Handwritten comments on each slide mount were transcribed into a database to
enable interactive image searches. Some of the handwriten annotations were hard
to decipher. The original notebook pages were scanned into PDF format files to
allow users to actually study the hand annotations. The page scans can be
downloaded using links at the top of each "Reconstructed Slide Notebook" page.