Slide Scanning

Slide Scanning
Converting Your Film Photographs
to Digital
Presentation to UCHUG - 8/06/08
G. Skalka
Why Scan?
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Film and prints degrade - bits do not
Infinite identical copies of digital image
Storage space is reduced
Easier to edit and enhance digital photos
Easier to view (with computer vs. projector)
Easier to share
Film Photography
• Color photographic film contains three
emulsion layers
– Each contains silver salts that are sensitive to a
particular frequency range (color) of light
– Blue, Red and Green are recorded separately
– Colored dyes replace the silver salts in the film
during developing, forming color images
• The dyes break down over time, accelerated
by heat and light
Film Types
• Negative Film
– Produces color negatives, from which color
prints are made
– Most cost-effective film type when prints are
needed
• Reversal Film
– Produces color transparencies (slides)
– Less expensive to use than negative or print
film (unless prints are needed)
Film Size
• 35 mm (also called 135) was and is the most
popular type of roll film
• 35 mm wide film strip
– Image size is 36 mm x 24 mm
Digital Photography
• Images are recorded in pixels, the smallest
piece of information in the image
• Digital cameras use an image sensor to
convert the visual image directly to digital
bits
– Sensors consist of a large number of single
sensor elements, in an array
• Scanners use image sensors to convert the
image recorded on film to digital
Resolution
• Rendering an optical view (in a digital
camera) or image (in a scanner) with more
pixels (higher resolution) results in a more
accurate representation
• Digital Camera Resolution
– Measured in pixels (or typically megapixels)
– 3072 x 2304 pixels provides 7.1 megapixels
Resolution
• Scanner Resolution
– Measured in dpi (dots per inch), or more
accurately, ppi (pixels per inch) or spi (samples
per inch)
• Film Resolution
– Measured in lines, the number of adjacent lines
(paired as one light and one dark) that can be
resolved). Photographic film has 3000 - 6000
lines per inch.
Resolution
• Print Resolution
– Measured in dpi
– Typical resolution for photographic print paper
is 300 dpi
Should You Scan Prints or Film?
• Film is original - Print is second generation
copy
• Film is higher resolution (10x, 3000 dpi
min. vs. 300 dpi)
– At 300 dpi, the equivalent full-resolution print
from 35 mm film would be 14” x 9.4”
– Only scanning a large print yields a better
digital image (assumes scanners can take
advantage of full resolution in each case)
If Scanning a Print Makes the
Most Sense
• Scan the largest print available
• Make sure the scanner glass is clean
• Scan at 300 dpi maximum
– At 300 dpi print resolution, no additional
information is available for higher resolution
scans
– Higher scanning resolution makes file size
unnecessarily large
Film Scanning Options
• Two basic choices
– Flatbed scanner with transparency adapter
– Dedicated film scanner
• Third choice - use a scanning service
Flatbed Scanners
• Require a transparency adapter to scan film
– An additional calibrated light source opposite
the film from the sensor
– Light from transparency adapter passes through
film to sensor
– Light must also pass through glass plate
• Resolutions of 4800 dpi to 9600 dpi
• $80 to $500
• Can also scan prints and documents
Film Scanners
• Dedicated to slide / negative scanning
(typically 35 mm only)
• Generally higher image quality for film
• Resolutions up to 5400 dpi
• $100 to $5000
• Can include auto-feed for both mounted
slides and strip film
Film Scanning Service
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You send in film - they digitize
Can provide digital editing and optimization
Can provide on CD, DVD or online
$0.50 - $0.90 per slide or negative
Many services available - probably many
results as well
• Ask about scan resolutions and file formats
How Much Resolution is
Needed?
• 35 mm film is 3000 to 6000 dpi, or
equivalent to 12 to 48 megapixels
• To print from scan of film
– 11” x 14” print requires minimum 3000 dpi
scan or 12 megapixel file
– 8” x 10” print requires minimum 2400 dpi scan
or 7.7 megapixel file
– 5” x 7” print requires minimum 1400 dpi scan
or 2.6 megapixel file
Digital Image File Formats
• PNG - Portable Network Graphics - .png
– Lossless compression - approx. 75% of TIFF
– Fairly well supported
• TIFF - Tag Image File Format - .tif
– Uncompressed; can have lossless compression
– Most universal commercial format
• JPEG - Joint Photographic Experts Group
– Lossy compression provides files 10% of TIFF
– Most popular for digital photo exchange
What File Format to Use?
• PNG or TIFF for archiving
• JPEG for displaying or sharing
• I recommend storing masters as PNG, and
converting to JPEG for use and display
– Not all my scanning software supports PNG, so
conversion from TIFF may be necessary
– I may need to look for better scanning software
My Four Film Scanners
• HP ScanJet 5370 Cxi Flatbed w/TMA
– 1200 dpi (1.9 megapixel), $300 in 1998
• PrimeFilm 1800u Film Scanner
– 1800 dpi (4.4 megapixel), $120 in 2003
• Microtek ScanMaker S400 Flatbed w/TMA
– 4800 dpi (30.8 megapixel), $80 in 2006
• PrimeFilm 3600u Film Scanner
– 3600 dpi (17.4 megapixel), $120 in 2008
HP ScanJet Cxi Flatbed
• 1200 dpi flatbed, scan time = 1 min
HP ScanJet Cxi Flatbed
• Has transparent media adapter (TMA) and
holders for both mounted slider and strip
film / negatives
Test Slide
Resolution Test
75 dpi
300 dpi
0.7 MB
10.2 MB
100 dpi
1.2 MB
600 dpi
37.4 MB
150 dpi
1200 dpi
2.6 MB
123.8 MB
200 dpi
Auto
4.7 MB
(200 dpi)
4.7 MB
Test Negative (as Slide)
Test Negative (as Negative)
Pacific Image Electronics
PrimeFilm 1800u
• 1800 dpi film scanner
• Subset of 3600u capabilities
Microtek ScanMaker S400
• 4800 dpi flatbed, scan time = 4 - 9 minutes
Microtek ScanMaker S400
• Has transparent media adapter (TMA),
which holds both mounted slides and strip
film / negatives
Resolution Test
100 dpi
1200 dpi
0.042 MB
5.1 MB
150 dpi
0.088 MB
2400 dpi
19.5 MB
300 dpi
3200 dpi
0.33 MB
33.9 MB
600 dpi
4800 dpi
1.3 MB
72.7 MB
Test Negative (as Slide)
Test Negative (as Negative)
Pacific Image Electronics
PrimeFilm 3600u
• 3600 dpi film scanner for film and slides
• Scan times of 1 - 4 minutes
Resolution Test
72 dpi
1800 dpi
0.022 MB
9.8 MB
300 dpi
0.32 MB
2400 dpi
18.1 MB
720 dpi
3000 dpi
1.7 MB
28.0 MB
1200 dpi
3600 dpi
4.5 MB
39.7 MB
Test Negative (as Slide)
Test Negative (as Negative)
Relative Negative Scan Quality
HP
Microtek
PrimeFilm
Relative Resolution Quality
1200 dpi
HP
4800 dpi
Microtek
3600 dpi
PrimeFilm
Scan Capacities
• HP can scan 1-4 mounted slides or 1-8 strip
film images (negatives)
• Microtek can scan 1-4 mounted slides or 16 film images (negatives)
• PrimeFilm can scan 1 mounted slide or strip
film image
Scanning Multiple Images
• Reduces loading time per scan
• Scanning time is proportionally larger than
single slide
• Photo editing software time is required to
crop and save individual images separately
Develop a Scan Methodology
• Determine the minimum resolution you
need
– For future printing
– For display and general use
• Consider scanning at multiple resolutions
– High resolution for important or significant
photos
– Lower resolution for less significant shots
– Consider which slides are not significant
enough to warrant scanning at all
Hints for Better Scans
• Clean the glass on flatbed scanners
• Blow dust out of film scanner with canned
air periodically
• Remove dust from film with a photo brush
or canned air just before scanning
Acknowledgements
• World Book Encyclopedia, “Photography”,
1970, Field Enterprises Educational Corp.
• Wikipedia - 135 Film, 35 mm, Image
Resolution, Pixel, Image Scanner
• Scantips.com, Wayne Fulton
• Hewlett Packard, hp.com
• Pacific Image Electronics, scanace.com