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Digital Support Services (DSS)
Smathers Libraries
University of Florida
P.O Box 117003
Gainesville, FL 32611 USA

P: 352.273.2900
F: 352.392.6597
UFDC@uflib.ufl.edu



Digital Library Center Documentation: Imaging Standards

 

Master TIFF Images:
TIFF files created through a process of scanning are archived as masters and used to derive other file formats for Web delivery.
File Format: ITU TIFF (Tagged Image File Format)

Encoding:

6.0 (ITU T.6)
Specification: TIFF 6.0 Specification (PDF file version)

Compression:

Uncompressed

Bit-depth:

Appropriate to the source document and for intended uses (e.g., facsimile reproduction)

DPI:

Appropriate to the source document and for intended uses (e.g., high resolution printing, optical character recognition, etc.)

Scale/Image Dimensions:

Scan scaled to 100% of source document dimensions

Color Space: sRGB
Scanning software calibrated to standard RGB palate
Derived JPEG Images: automatically created by the toolkit during PreQC
File Format: JPEG
Specification: ISO 10918-1/2
Reference:
Encoding

Compression:

Minimum (highest image quality),
Not greater than 15% (image quality not less than 85% of source file)

Bit-depth:

Same as source file

DPI:

Same as source file.
Mitigation of scaling may require down-sampling or Gaussian blur. These processes require skill and experience.

Scale/Image Dimensions:

Width = 630 pixels; Height = variable
Maintain original image aspect ratio

Interpolation: Resample
Derived JPEG2000 Images: automatically created by the toolkit during PreQC
File Format: JPEG 2000
Specification: ISO/IEC 15444-1
Reference: http://www.jpeg.org/jpeg2000/

Encoding:

6.0 (ITU T.6)
Specification: TIFF 6.0 Specification (PDF file version)

Compression:

Minimum (highest image quality),
Range from 10% to 15% (image quality not less than 85% of source file)

Bit-depth:

Same as source file

DPI:

Same as source file

Scale/Image Dimensions:

Same as source file

Derived JPEG Thumbnails: automatically created by the toolkit during PreQC
File Format: JPEG (Joint Photographic Expert Group)
Specification: ISO 10918-1/2

Encoding:

Standard

Compression:

Minimum (highest image quality)
Not greater than 15% (image quality not less than 85% of source file)

Bit-depth:

Same as source file

DPI:

Same as source file

Scale/Image Dimensions:

Width = 100 pixels; Height = variable
Maintain original image aspect ratio

Interpolation:

Resample

All images are captured at bit depths and resolutions appropriate to textual and binding characteristics. Tightness of binding, fragility of paper and/or binding, type face characteristics, and physical size of the item necessitate use of various capture devices. Past experience indicates that only 50% of the Baldwin volumes are likely to be suitable for capture by the fastest method: the Copibook scanner. Other volumes will need to be scanned by slower but less rigorous methods using the Microtek 9800 XL flatbed scanner, an Epson 1640 XL flatbed scanner, or a 13.7-MP (mega-pixel) Kodak DCS 14n planetary digital camera. When appropriately calibrated, this equipment achieves highly accurate capture in grey scale and color. Capture is sufficient to meet Quality Index requirements as calculated by Cornell University and widely used within the library digitization community as a standard for determining requisite digital resolution, i.e., dpi. (See Benchmarking for Digital Capture (http://www.library.cornell.edu/preservation/tutorial/conversion/conversion-04.html) and Establishing a Central Depository for Preserving Digital Image Collections (http://www.library.cornell.edu/imls/image%20deposit%20guidelines.pdf) Specifications for the capture equipment and the book cradle used with the Kodak camera are given in Appendices for grant proposals.

Scanning methods chosen depend on the document characteristics, but follow the principals and recommendations set forth in Moving Theory into Practice: Digital Imaging for
Libraries and Archives (Anne R. Kenney and Oya Y. Rieger [Mountain View, Ca : Research Libraries group, 2000]) and Cornell University’s Digital Imaging Tutorial
(http://www.library.cornell.edu/preservation/tutorial/contents.html).

Digital Images: The Guidelines for Master TIFF Image Files employed by this project are those established by the University of Florida for the Digital Library of the Caribbean cooperative, and by the World Digital Library for partners (http://project.wdl.org/standards/imagestandards.html). The master files are uncompressed TIFF (ITU T.6) images. Scans are scaled to 100% of the source document dimensions. Bit-depth is 24-bit color or 8-bit gray scale; dpi is 300 at a minimum. Color space is sRGB with scanning software calibrated to a standard RGB palate. Derivative jpg2000 zoomable images and jpg files are created for use for web serving.

Images are captured onto 8 TB (terabyte) storage area network (SAN) connected via network cabling to computer workstations running Microsoft Windows XP or higher and Adobe Photoshop CS 4 or higher. Image processing routines are conservative and are intended to maintain original image quality. Image de-skew, cropping, and color correction are the common corrections needed.

Because color management of images is important in this project, calibration of equipment are monitored continuously. Digital camera color fidelity is achieved by color balancing the digital camera with ANSI IT8.7/2-1993 (Graphic Technology _Color Reflection Target for Input Scanner Calibration. Washington, D.C.: American National Standards Institute, last revised 1993) compliant specifications through the use of targets such as Kodak Q-60 and Q-13. Flatbed scanner color fidelity is achieved through bundled Q-60 based calibration programs, and the CopiBook is calibrated through its integrated calibration utility. Monitor gamma and color calibration is achieved through Monaco Optix 2.0. The supervising technicians have academic training in both photographic and digital imaging techniques and will determine the correct tonal values for the 24-bit image according to Q-60 and Q-13 calibrations and adjust each image to optimize tone and contrast, assuring color fidelity.

Resources

Evaluating Digital Image Performance

Last modified: Tuesday December 06 2011 lnt