NARA Guidelines for Digitizing Archival Materials for Electronic Access

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

NARA Guidelines for Digitizing

Archival Materials for Electronic Access

National Archives and Records Administration Date: January 1998

8601 Adelphi Road, College Park, MD 20740, USA

Researched, Written, and Compiled By: Steven Puglia, Preservation and Imaging Specialist,

and Barry Roginski, Computer Specialist

NOTE: The NARA Guidelines for Digitizing Archival Materials for Electronic Access presented here have

been developed solely for internal NARA use in our pilot Electronic Access Project. We are posting the

Guidelines on this site in response to requests. We welcome your comments and suggestions. In review-

ing this document, please keep in mind the following:

•The Guidelines are not intended to be promulgated as a standard for digital imaging. The Guide-

lines cover only the process of digitizing archival materials for on-line access through the Elec-

tronic Access Project. Other issues that must be considered in conducting digital imaging projects,

including preservation, are not addressed here.

•The Guidelines do not constitute, in any way, guidance to Federal agencies on records creation or

transfer to the National Archives of the United States.

Digital Imaging Requirements

The goal of the National Archives and Records Administration’s Electronic Access Project (EAP)

is to produce an on-line catalog that will provide information about NARA holdings and a core

collection of digital copies of selected high-interest documents.

These digitizing specifications have been developed to provide a method of evaluating the qual-

ity of images produced, to estimate the data storage for access files (on-line) and master files (off-

line), and to assist in determining upgrades to the NARA network infrastructure. Inherent dif-

ferences in document types dictate different approaches to scanning. Due to inconsistent legibil-

ity throughout NARA’s holdings, due to the desire to image documents in a consistent manner,

and due to the limited number of records to be digitized (approximately 120,000 to 200,000 in the

initial phase), all scanning will be 8-bit grayscale or 24-bit color.

The tone reproduction approach for digitizing images has been geared toward providing good

monitor representation, based on an “average” computer monitor determined by the visual evalu-

ation of a selection and variety of monitors. The tone reproduction is to be done consistently for

all images to facilitate the batch processing of derivative files or future adjustments to the distri-

bution of the tones.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

Specifications have been developed for the following types of materials-

Textual Documents

Media formats to be provided for scanning include, original records, photo-

copies, photographic copy negatives or copy transparencies, or microfilm.

The scanning resolution for the master files of 300 dpi for smaller docu-

ments was selected to be compatible with OCR software. The lower scan-

ning resolution of 200 dpi for larger documents was selected to be of repro-

duction quality and to save file storage space.

Photographs

Media formats to be provided for scanning include B&W and color photo-

graphic prints, negatives, or transparencies. The digital image size for the

master files of 3,000 pixels across the long dimension was selected to be of

reproduction quality. A magazine quality halftone reproduction at 11”x14”

in size and 133 lpi is achievable from this file size.

Maps, Plans, and Oversized Records

Media formats to be provided for scanning includes original records, photo-

copies, photographic copy negatives or copy transparencies, or microfilm.

The scanning resolution for the master files of 300 dpi for smaller docu-

ments was selected to be compatible with OCR software. The lower scan-

ning resolution of 200 dpi for larger documents was selected to be of repro-

duction quality and to save file storage space.

Graphic Records

Line drawings, artistic illustrations, and other similar records. Media for-

mats to be provided for scanning include original records, photocopies, pho-

tographic copy negatives or copy transparencies, or microfilm. Smaller

graphic records are scanned in the same manner as photographs and larger

graphic records are scanned in the same manner as maps, plans, and over-

sized records.

Comments on Derivative Files

The resolution or size and the file formats for the access files and thumbnail files have been

selected to facilitate speed of transfer via the Internet and to minimize the requirement for high

speed CPUs and large amounts of memory on the end users computer. Optional large access file

requirements are proposed here and may be added to NARA’s EAP at some point in the future as

Internet bandwidth increases. All derivative files are intended to be produced in an automated

batch processing mode.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

MASTER IMAGE FILES

Pixel Depth:

8 bit grayscale or 24 bit color, RGB mode.

Resolution and Image Size- Textual Documents and Maps/Plans/Oversized Records:

300 dpi effective resolution for original documents SMALLER than or EQUAL to

11”x17” or 187 sq. inches in size and 200 dpi effective resolution for original docu-

ments LARGER than 11”x17” or 187 sq. inches. Image size shall be the size of the

original document at the scan resolution; examples: 8”x12” at 300 dpi or 16.5”x20.5”

at 200 dpi.

Scanner or digital camera shall provide true optical resolution of at least 300 dpi

effective resolution for the original documents; interpolating to a higher resolution

from a lower resolution scan shall not be permitted.

Resolution and Image Size- Photographs:

Adjust scanning resolution to produce files with pixel arrays of 3000 pixels across

the long image dimension by the proportional number of pixels for the specific

photo format; example: 3000 pixels by 2400 pixels for 8”x10” or 4”x5” prints or

negatives, 3000 pixels by 2000 pixels for 35mm slides or negatives or 4”x6” prints.

For square images, adjust resolution to produce files with pixel arrays of 2700 pix-

els by 2700 pixels.

Final image size shall be set to a standard 10” across the long dimension at 300 dpi;

examples: 8”x10” at 300 dpi for a 4”x5” negative or 6.7”x10” at 300 dpi for a 35mm

slide. Square images shall be set to a standard 9”x9” at 300 dpi.

Scanner or digital camera shall provide true optical resolution of at least 3000 pix-

els across the long dimension of the image; interpolating to a higher resolution

from a lower resolution scan shall not be permitted.

Resolution and Image Size- Graphic Records:

Adjust scanning resolution to produce files with pixel arrays of 3000 pixels across

the long image dimension by the proportional number of pixels for original docu-

ments SMALLER than or EQUAL to 11”x17” or 187 sq. inches in size. Final image

size shall be set to a standard 10” across the long dimension at 300 dpi and square

images shall be set to a standard 9”x9” at 300 dpi.

200 dpi effective resolution for original documents LARGER than 11”x17” or 187

sq. inches. Image size shall be the size of the original document at the scan resolu-

tion; example: 16.5”x20.5” at 200 dpi.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

Scanner or digital camera shall provide true optical resolution of at least 3000 lines

or 300 dpi effective resolution for the original documents; interpolating to a higher

resolution from a lower resolution scan shall not be permitted.

File Format:

Uncompressed TIFF files with Intel byte order and header version 6.

Scanning Aimpoint Values:

•Using a Kodak Gray Scale (Q-13 or Q-14) or equivalent photographic reflection

gray scale- The gray scale is preferred because it is photographic and is more con-

sistent from one copy of the gray scale to another.

Patch “A” or visual density of 0 to 0.10 to be rendered at RGB levels of

247 - 247 - 247 or at a % black of 3%.

Patch “M” or visual density of 0.70 to 0.80 to be rendered at RGB levels of

105 - 105 - 105 or at a % black of 59%.

Patch “19” or visual density of 1.90 to 2.00 to be rendered at RGB levels of

8 - 8 - 8 or at a % black of 97%.

•Using Kodak Color Control Patches (Q-13 or Q-14)- It is less desirable to use the

color patches because they are printed on a printing press, they tend to be less

accurate in color and density and to be less consistent from one copy of the color

patches to another. The RGB values cited below are the average values for theKodak

color bars measured from actual scans that were adjusted for the Kodak gray scale.

White patch to be rendered at RGB levels of 241 - 241 - 241 or at a % black

of 5%.

Gray background to be rendered at RGB levels of 101 - 101 - 101 or at a

% black of 60%.

Single color black to be rendered at RGB levels of 19 - 19 - 19 or at a % black

of 93%.

•Minimum and maximum RGB or % black levels when scanning materials with no

reference gray scale or color patches, such as original photographic negatives:

For RGB scanning the highlight not to go above RGB levels of 247 - 247 - 247

and shadow not to go below RGB levels of 8 - 8 - 8.

For grayscale scanning the highlight not to go below % black of 3 % and

shadow not to go above % black of 97%.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

Scanning Aimpoint Variability:

•For RGB scanning- No more than a

+ 3 RGB level variance from each aimpoint

and no more than a 3 RGB level difference in the individual channels within each

specified patch on the Kodak Gray Scale or Color Patches.

•For grayscale scanning- No more than a

+ 1% variation in % black from each

aimpoint for the specified patches on the Kodak Gray Scale.

Maximum Tonal Range:

Generally, the RGB levels for a color image should range from 8 to 247 for a total of

240 levels or shades per channel and the % black for a grey scale image should

range between 3% to 97%. The dynamic head-room at both ends of the scale is to

ensure no loss of detail or clipping in scanning and to accommodate the slight

expansion of the tonal range due to unsharp mask filtering. However, to accu-

rately represent some digital images of certain documents, such as faded ink on

darkened paper for a textual document or a low contrast photographic print, the

tonal range may be significantly less than the maximum range cited above.

Tone Reproduction Control:

Use scanner controls to place white-point (patch “A” on Kodak gray scale or high-

light detail on an original photographic negative) and black-point (patch “19” on

Kodak gray scale or shadow detail on an original photographic negative) at de-

sired RGB levels or % black. Use scanner gamma control to place “M” step value or

to adjust tonal distribution for good monitor representation of the image. After

scanning use Adobe Photoshop “levels” control for minor correction only; use the

place black-point, place white-point, place mid-point and slider controls in that

order.

Scanner Calibration:

For original documents, photocopies, and photographic prints (B&W and color),

calibrate the scanner to a Kodak gray scale. Sometimes when scanning photographic

prints the low and high densities of the print are lighter and/or darker than those

on the gray scale; check the RGB levels or % black of the image area on a preview

scan and, if the print densities are lighter and/or darker, place the those densities

at the appropriate aimpoint values cited above rather than using the gray scale.

For copy negatives (B&W and color), if the copy negative has a Kodak gray scale

in the image, adjust the scanner settings using the image of the gray scale to meet

the above requirements. If there is no gray scale, the scanner software shall be used

to match the tonal scale of the digital image to the density range of the specific

negative being scanned and to provide an image adjusted for monitor representa-

tion.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

For color copy transparencies and color microfilm, if the copy transparency has a

Kodak gray scale in the image, adjust the scanner settings using the image of the

gray scale to meet the above requirements. If there is no gray scale, the scanner

software shall be used to match the tonal scale and color balance of the digital

image to the specific transparency being scanned to provide an accurate monitor

representation of the image on the transparency.

For original color transparencies, the scanner software shall be used to match the

tonal scale and color balance of the digital image to the specific transparency being

scanned to provide accurate monitor representation of the image on the transpar-

ency.

For B&W microfilm, scanner software shall be used to match the tonal scale of the

digital image to the density range of the specific negative or positive microfilm

being scanned; example: the minimum density of negative microfilm placed at a %

black value of 97% and the high density placed at a % black value of 3% (% black

values as indicated in Adobe Photoshop).

For original photographic negatives (B&W and color), scanner software shall be

used to match the tonal scale of the digital image to the density range of the nega-

tive being scanned and to adjust color balance for color negatives. Use place white-

point, place black-point, and scanner gamma control or use histogram control to

adjust or control tones in a manner similar to making a photographic print in the

darkroom.

Monitor Calibration:

The monitors of the scanning and quality control workstations shall be set to 24

bits (millions of colors), a gamma of 2.2, and a color temperature of 6500˚K. Con-

sider calibrating monitor to proposed sRGB color space.

The monitors of the scanning and quality control workstations shall be adjusted,

using visual evaluation, to the NARA Monitor Adjustment Target. Second, the

monitors shall be calibrated using a photosensor-based color calibrator to ensure

neutral color balance and linearity of the red, green, and blue representation on the

monitor. Finally, a Kodak grayscale shall be scanned, the aimpoint values matched,

and then final contrast and brightness adjustments shall be made on the monitors

while visually comparing the scan and the Kodak gray scale.

National Archives Monitor Adjustment Target:

NARA shall provide a monitor adjustment target as a digital image file for use with

all types of computer monitors. The NARA target shall be used to adjust all scan-

ning and viewing workstation monitors.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

This target has been designed to allow computer users to adjust the contrast and

brightness of their computer monitor so that graphic images, such as scans of pho-

tographs, textual documents, or maps look their best. The digital images for NARA’s

Electronic Access Project have been scanned to provide a reasonably accurate ren-

dition of the documents when viewed on an “average” computer monitor that has

been adjusted to the target. The generic or “average” monitor representation was

determined by visual evaluation of a large selection and variety of monitors, in-

cluding both Windows computers set to a default gamma of 2.2 and Macintosh

computers set to gammas of both 1.8 and 2.2.

Tonal Scale and Color Balance Adjustments:

All tonal scale and color balance adjustments should be controlled with the scan-

ner software, minimal tonal scale and color balance adjustments shall be done to

the image after scanning.

Sharpening:

Image files shall be sharpened as needed to achieve the approximate appearance of

the original. All sharpening shall be done with an unsharp mask algorithm. Level

of filtering will vary depending on the scanner and the material being scanned.

Typical unsharp mask parameters- Amount 100% to 200%

Radius 1 to 2 pixels

Threshold 2 to 8 levels

For master file images, the amount of sharpening is usually at the higher end and

the radius is usually at the lower end of the ranges cited above. Usually threshold

can be set and used at a single value, such as 4 levels.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

TIFF Header Information:

Common usage for specific header tags shall be followed, “typical” or “expected”

data shall be provided for most tags and exceptions are noted in the following list.

The following list conforms to Library of Congress TIFF header tag requirements-

Description Tag Comments/Required Data

NewSubfileType 254

ImageWidth 256 actual pixel count

ImageLength 257 actual pixel count

BitsPerSample 258

Compression 259

PhotometricInterpretation 262

DocumentName 269 NARA assigned doc. name

ImageDescription 270 orientation- portrait, landscape, or

square

StripOffsets 273

SamplesPerPixel 277

RowsPerStrip 278

StripByteCounts 279

XResolution 282 actual pixel count

YResolution 283 actual pixel count

ResolutionUnit 296

DateTime 306 date and time scanned

Artist 315 NARA

In order for the digital images to open in all software packages, the TIFF header

tags shall be sorted in ascending numerical order.

OPTIONAL: LARGE ACCESS FILES (Not being produced for NARA’s EAP at this time.)

Textual Documents- For documents LARGER than 8.5”x14” or 119 sq. inches in size regardless

of character height and for documents SMALLER than or EQUAL to 8.5”x14” or 119 sq. inches

with character height of SMALLER than or EQUAL to 1.5mm.

Pixel Depth and File Format:

8 bit grayscale JPEG for grayscale images and 24 bit color JPEG, RGB mode,

for color images for documents LARGER than 8.5”x14” or 119 sq. inches in

size regardless of character height* and for documents SMALLER than or

EQUAL to 8.5”x14” or 119 sq. inches with character height* of SMALLER

than or EQUAL to 1.5mm. JPEG compression shall be set at medium or low

quality or approximately 10:1 to 20:1 compression. The image size shall be

the size of the original document at a resolution as specified below; example:

8”x12” at 125 dpi.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Image Size:

Images shall be resized from 300 dpi or 200 dpi master files to a smaller

image size using the following settings-

90 dpi for 2.0 mm or larger character height.*

125 dpi for 1.5 mm character height.*

200 dpi for 1.0 mm or smaller character height.*

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Photographs-

Pixel Depth and File Format:

8 bit grayscale JPEG for grayscale images and 24 bit color JPEG, RGB mode,

for color images. JPEG compression shall be set at medium to low quality or

approximately 10:1 to 20:1 compression.

Image Size:

3000 pixel dimension of master files shall be reduced to 1500 pixels across

the long image dimension by the proportional number of pixels for the spe-

cific photo format; example: 1500 pixels by 1200 pixels for 8”x10” or 4”x5”

prints or negatives, 1500 pixels by 1000 pixels for 35mm slides or negatives

or 4”x6” prints. For square images, files shall be reduced to 1340 pixels by

1340 pixels.

Final image resolution for large access files shall be a default resolution of

150 dpi and the image size shall be 10” across the long dimension for rectan-

gular images and 9”x9” for square images.

Maps, Plans, and Oversized Records-

Pixel Depth and File Format:

4 bit interlaced/89a GIF files for 8 bit grayscale images and 8 bit interlaced/

89a GIF files for 24 bit color images for documents SMALLER than or EQUAL

to 8.5”x14” or 119 sq. inches with character height* of LARGER than 1.5mm.

The image size shall be the size of the original document at a resolution as

specified below; example: 8”x12” at 125 dpi.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

8 bit grayscale JPEG for grayscale images and 24 bit color JPEG, RGB mode,

for color images for documents LARGER than 8.5”x14” or 119 sq. inches in

size regardless of character height* and for documents SMALLER than or

EQUAL to 8.5”x14” or 119 sq. inches with character height* of SMALLER

than or EQUAL to 1.5mm. JPEG compression shall be set at low quality or

approximately 20:1 or higher compression. The image size shall be the size

of the original document at a resolution as specified below; example: 20”x24”

at 90 dpi.

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Image Size:

Images shall be resized from 300 dpi to a smaller image size using the fol-

lowing settings-

90 dpi for 2.0 mm or larger character height.*

125 dpi for 1.5 mm character height.*

200 dpi for 1.0 mm or smaller character height.*

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Graphic Records-

Pixel Depth and File Format:

8 bit grayscale JPEG for grayscale images and 24 bit color JPEG, RGB mode,

for color images. JPEG compression shall be set at medium to low quality or

approximately 10:1 to 20:1 compression.

Image Size:

For documents SMALLER than or EQUAL to 11”x17” or 187 sq. inches, the

3000 pixel dimension of master files shall be reduced to 1500 pixels across

the long image dimension by the proportional number of pixels for the spe-

cific photo format; for example- 1500 pixels by 1200 pixels for 8”x10” or

4”x5” prints or negatives, 1500 pixels by 1000 pixels for 35mm slides or nega-

tives or 4”x6” prints. For square images, files shall be reduced to 1340 pixels

by 1340 pixels. Final image resolution for large access files shall be a default

resolution of 150 dpi and the image size shall be 10” across the long dimen-

sion for rectangular images and 9”x9” for square images.

For documents LARGER than 11”x17” or 187 sq. inches, the images shall be

resized from 200 dpi to a smaller image size using the following settings.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

The image size shall be the size of the original document at a resolution as

specified below; example- 20”x24” at 90 dpi:

90 dpi for 2.0 mm or larger character height.*

125 dpi for 1.5 mm character height.*

200 dpi for 1.0 mm or smaller character height.*

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Resizing:

The large access files shall be produced by resizing from the master image files; an

interpolation algorithm that provides high quality results, such as bicubic interpo-

lation, shall be used.

Blurring and Resharpening:

All files will be blurred prior to resizing using a blur filter. After resizing, all files

shall be sharpened as needed to achieve the approximate appearance of the origi-

nal. All sharpening shall be done with an unsharp mask algorithm.

See typical unsharp mask parameters cited above.

Tonal Scale and Color Balance:

Since the large access files are derived from the master files, there should not be a

need for adjustments to the tonal scale or color balance, all adjustments should be

done to the master image files. If any tonal scale and color balance adjustments are

needed, the tonal scale and color balance shall be adjusted using “levels” control to

produce a compromise setting for viewing on monitor set to a gamma of 2.2 and

visually calibrated to the NARA Monitor Calibration Target.

Global adjustments using “brightness”, “contrast”, and “color balance” controls

should not be used.

Color Palette and Dithering:

8 bit color files shall use a custom/adaptive 256 color palette generated from each

individual image. All dithering shall be done using a diffusion dither algorithm

and all dithering shall be performed after sharpening the image.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

ACCESS FILES

Textual Documents-

Pixel Depth and File Format:

4 bit interlaced/89a GIF files for 8 bit grayscale images or 8 bit interlaced/

89a GIF files for 24 bit color images for documents SMALLER than or EQUAL

to 8.5”x14” or 119 sq. inches. Resize image to 90 dpi at original size and let

GIF file default to 72 dpi at larger than original size.

8 bit grayscale JPEG for grayscale images or 24 bit color JPEG, RGB mode,

for color images for documents LARGER than 8.5”x14” or 119 sq. inches in

size. The image size shall be the size of the original document at the dpi

specified below; example: 16.5”x20.5” at 90 dpi.

Image Size:

Images shall be resized from 300 dpi or 200 dpi master files to a smaller

image size using the following settings-

90 dpi regardless of character height*.

OPTIONAL-

72 dpi for character height* of 1.5mm or larger.

90 dpi for character height* smaller than 1.5 mm.

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Photographs-

Pixel Depth and File Format:

4 bit interlaced/89a GIF files for 8 bit grayscale images.

8 bit interlaced/89a GIF files for 24 bit color images.

Image Size:

3000 pixel dimension of master files shall be reduced to 600 pixels across the

long image dimension by the proportional number of pixels for the specific

photo format; example: 600 pixels by 480 pixels for 8”x10” or 4”x5” prints or

negatives, 600 pixels by 400 pixels for 35mm slides or negatives or 4”x6”

prints. For square images, files shall be reduced to 540 pixels by 540 pixels.

Final image resolution for access files shall be a default resolution of 72 dpi.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

Maps, Plans, and Oversized Records-

Pixel Depth and File Format:

8 bit grayscale JPEG for grayscale images or 24 bit color JPEG, RGB mode,

for color images for documents. JPEG compression shall be set at low qual-

ity or approximately 20:1 or higher compression.

Image Size:

Files shall be resized to 1200 pixels across the long image dimension by the

proportional number of pixels for the specific document; for example- 1200

pixels by 960 pixels for 16”x20” or 24”x30” documents, 1200 pixels by 800

pixels for 40”x60” documents. For square documents, files shall be reduced

to 1070 pixels by 1070 pixels.

Final image size shall be set to a standard 10” across the long dimension at

120 dpi and square images shall be set to a standard 9”x9” at 120 dpi.

Graphic Records-

Pixel Depth and File Format:

4 bit interlaced/89a GIF files for 8 bit grayscale images or 8 bit interlaced/

89a GIF files for 24 bit color images for documents SMALLER than or EQUAL

to 11”x17” or 187 sq. inches.

8 bit grayscale JPEG for grayscale images or 24 bit color JPEG, RGB mode,

for color images for documents LARGER than 11”x17” or 187 sq. inches in

size.

Image Size:

For documents SMALLER than or EQUAL to 11”x17” or 187 sq. inches, the

3000 pixel dimension of master files shall be reduced to 600 pixels across the

long image dimension by the proportional number of pixels at a default

resolution of 72 dpi. For square images, files shall be reduced to 540 pixels

by 540 pixels at a default resolution of 72 dpi.

For documents LARGER than 11”x17” or 187 sq. inches, files shall be resized

to 1200 pixels across the long image dimension by the proportional number

of pixels for the specific document; example: 1200 pixels by 960 pixels for

16”x20” or 24”x30” documents, 1200 pixels by 800 pixels for 40”x60” docu-

ments. For square documents, files shall be reduced to 1070 pixels by 1070

pixels.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

Final image size shall be set to a standard 10” across the long dimension at

120 dpi and square images shall be set to a standard 9”x9” at 120 dpi.

OPTIONAL-

For documents LARGER than 11”x17” or 187 sq. inches, images shall be

resized from 200 dpi master files to a smaller image size using the following

settings and image size shall be the size of the original document at 72 dpi or

90 dpi-

72 dpi for character height* of 1.5mm or larger.

90 dpi for character height* smaller than 1.5 mm.

*Height of lower case character (usually lower case “e”) of the small-

est type size on the document.

Resizing:

The access files shall be produced by resizing from the master files, or the large

access files if produced; an interpolation algorithm that provides high quality re-

sults, such as bicubic interpolation, shall be used.

Blurring and Resharpening:

All files will be blurred prior to resizing using a blur filter. After resizing, all files

shall be sharpened as needed to achieve the approximate appearance of the origi-

nal. All sharpening shall be done with an unsharp mask algorithm.

See typical unsharp mask parameters cited above.

Tonal Scale and Color Balance:

Since the access files are derived from the master files or large access files, there

should not be a need for adjustments to the tonal scale or color balance, all adjust-

ments should be done to the master image files. If any tonal scale and color balance

adjustments are needed, the tonal scale and color balance shall be adjusted using

“levels” control to produce a compromise setting for viewing on monitors set to a

gamma of 2.2 and visually calibrated to the NARA Monitor Calibration Target.

Global adjustments using “brightness”, “contrast”, and “color balance” controls

shall not be used.

Color Palette and Dithering:

8 bit color files shall use a custom/adaptive 256 color palette generated from each

individual image. All dithering shall be done using a diffusion dither algorithm

and all dithering shall be performed after sharpening the image.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

THUMBNAIL FILES:

Textual Documents, Photographs, Maps, Plans, Oversized Records, and

Graphic Records-

Pixel Depth and File Format:

4 bit interlaced/89a GIF files for 8 bit grayscale images.

8 bit interlaced/89a GIF files for 24 bit color images.

Image Size:

Not to exceed a pixel array of 200 pixels by 200 pixels, at a default resolution

of 72 dpi.

Resizing:

The thumbnail files shall be produced by resizing from the access image files; an

interpolation algorithm that provides high quality results, such as bicubic interpo-

lation, shall be used.

Blurring and Resharpening:

All files will be blurred prior to resizing using a blur filter. After resizing, all files

shall be sharpened as needed to achieve the approximate appearance of the origi-

nal. All sharpening shall be done with an unsharp mask algorithm.

See typical unsharp mask parameters cited above.

Tonal Scale and Color Balance:

Since the thumbnail files are derived from the access files there should be no need

for adjustments to the tonal scale or color balance; all adjustments should be done

to the master image files.

Color Palette and Dithering:

8 bit color files shall use a custom/adaptive 256 color palette generated from each

individual image. All dithering shall be done using a diffusion dither algorithm

and all dithering shall be performed after sharpening the image.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

Quality Assurance Procedures

A quality control program shall be initiated, documented, and maintained throughout all phases

of the digital conversion. The quality control plan shall address all specifications and reporting

requirements associated with each phase of the conversion project.

The unit/partner/contractor shall be responsible for performing all inspections or evaluations

of the quality of all digital images during production to ensure the quality of the digital images.

Reports

The unit/partner/contractor shall document all quality control procedures and actions taken

and the following specific reports shall be submitted.

Quality Control Summary: The unit/partner/contractor shall provide a summary report of all

quality control inspections performed for each batch of digital images produced. Report shall be

submitted with the digital files.

INSPECTION AND ACCEPTANCE/REJECTION

Inspection of Digital Files

Electronic Access Project/Digital Imaging Project shall require one (1) to two (2) weeks for evalu-

ating digital files, file name integrity, file header information, accuracy of tracking data, and

completeness of the batch prior to acceptance. Upon completion or receipt of a batch of digital

files, NARA will survey and evaluate a sampling of the digital images, including the master files,

the access files, and the thumbnail files. The overall quality of the digital images will be evalu-

ated using the following procedures.

At a minimum, 10 images or 10 % of each batch of digital images, whichever quantity is larger,

shall be inspected for compliance with the digital imaging specifications and for any one of the

following defects:

- image not the correct size

- image not the correct resolution

- incorrect file format

- incorrect mode, color image is a grayscale

- incorrect bit depth

- loss of detail in the highlights or shadows

- uneven tonal values or flare

- overall too light or too dark

- overall too low or too high contrast

- interference patterns (Newton's rings)

- lack of sharpness

- excessive sharpening, including unnatural appearance and halos around dark edges

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

- improper image orientation, such as backwards, up-side down, side-ways, etc.

- excessive noise, usually noticeable in the darker portions of the image

- misalignment of color channels in RGB images

- incomplete or cropped images

- excessively large border area

- image not centered or skewed images

- missing scan lines or dropped-out pixels

- image processing and scanner artifacts, such as extraneous lines, noise, banding, etc.

- dithering on master files or poor quality dithering on access or thumbnail files

- poor quality interpolation on small access files and thumbnail files

- overall color cast and inaccurate color balance

- improper file name

- incomplete or incorrect header information

The visual evaluation of the images shall be conducted while viewing the images at a 1 to 1 pixel

ratio or 100% magnification on the monitor.

Testing Results and Acceptance/Rejection

If more than 1% of the total number of images in a batch, based on the randomly selected sam-

pling, are found to be defective for any of the reasons listed above, the entire batch will be re-

turned to the unit/partner/contractor for reinspection of the batch and correction of the specific

errors found by NARA and any additional errors found by the unit/partner/contractor. If less

than 1% of the batch is found to be defective, then only the specific defective images that are

found shall be redone. The Electronic Access Project/Digital Imaging Project reserves the right to

reinspect the batch when it is resubmitted.

Document Handling Guidelines

The following instructions provide guidance on the proper handling of archival materials for

digitization.

1. Equipment

a. The unit/partner/contractor shall not use automatic feed devices, drum scanners or other

machines that require archival materials to be fed into rollers, that place more pressure on archi-

val materials than does an oversized electrostatic copier, or require the document to be taped to

a cylinder. The unit/partner/contractor may use automatic devices to digitize selected micro-

film or other materials identified by the Electronic Access Project Team/NARA.

b. The unit’s/partner’s/contractor's equipment shall have platens upon which physical items

are supported over their entire surface. The unit/partner/contractor shall ensure that no equip-

ment comes into contact with archival materials in a manner that causes friction.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

c. The unit/partner/contractor shall not use equipment having devices that exert pressure on or

that affix archival materials to any surface. The unit/partner/contractor shall not affix pressure

sensitive adhesive tape nor any other adhesive substance to any archival materials.

d. The unit/partner/contractor should not use equipment with light sources that raise the sur-

face temperature of the physical item being digitized. The unit/partner/contractor should filter

light sources that generate ultraviolet light.

e. The Electronic Access Project Team/NARA shall have the right to review and approve all

equipment.

2. Procedures

a. The unit/partner/contractor shall not leave archival materials unattended or uncovered on

digitizing equipment or elsewhere. The unit/partner/contractor shall return archival materials

left undigitized but needed for the next day’s work to their jackets and containers and place

them in the appropriate storage areas in the unit’s/partner’s/contractor’s work area. The unit/

partner/contractor shall return completed batches of archival materials to NARA staff in the

unit’s/partner’s/contractor’s work area.

b. The unit/partner/contractor shall place archival materials flat on the platen; rolling, pulling,

bending, or folding of archival materials is not permitted. The unit/partner/contractor shall

place only one physical item at a time on a surface appropriate for the item’s size and format,

except when scanning 35mm slides in a batch mode on a flat-bed scanner. The item shall be

supported over its entire surface on the platen; no part of an item shall overhang the platen so

that it is unsupported at any time. The unit/partner/contractor shall not place archival materi-

als that are warped, curling, or on warped and/or fragile mounts on the platen.

c. The unit/partner/contractor shall unroll and rewind or roll up archival materials carefully

(e.g., roll film, maps, etc.) as soon as the digitizing is finished. The unit/partner/contractor shall

rewind any rolls of film with the emulsion side in. The unit/partner/contractor shall rewind or

reroll archival materials in the same orientation as originally rolled.

d. The unit/partner/contractor shall handle archival materials in bound volumes carefully and

not force them open or place them face down. The unit/partner/contractor shall use book cradles

to support volumes.

e. The unit/partner/contractor shall not remove encapsulated archival materials from their en-

capsulation. The unit/partner/contractor may remove L-sleeves designated by NARA staff.

f. The unit/partner/contractor shall report archival materials which in his or her judgment can-

not be safely digitized and seek further guidance from the Electronic Access Project Team/NARA

staff before proceeding with digitizing.

US National Archives and Records Administration, 8601 Adelphi Road, College Park, MD 20740, USA. January 1998.

g. The unit/partner/contractor shall keep all archival materials in their original order and re-

turn them to their original jackets or containers. The unit/partner/contractor shall reinsert all

negatives removed from jackets in proper orientation with the emulsion side away from the

seams. The unit/partner/contractor shall keep any tracking paperwork with the archival mate-

rials or their containers.

h. The unit/partner/contractor shall not smoke, drink, or eat in the room where archival mate-

rials or their containers are located. Unit/partner/contractor staff shall clean their hands and

avoid the use of hand lotions before working with archival materials. The unit/partner/contrac-

tor shall not bring tobacco, liquids, and food into the room where archival materials or their

containers are located.

i. The unit/partner/contractor shall not place objects such as books, papers, pens, and pencils

on archival materials or their containers. The unit/partner/contractor shall use only lead pen-

cils as writing implements near archival materials or their containers. The unit/partner/con-

tractor shall not write on or otherwise mark archival materials, jackets, or containers.

j. The unit/partner/contractor shall not lean on, sit on, or otherwise apply pressure to archival

materials or their containers.

k. Unit/partner/contractor staff shall wear clean white cotton gloves at all times when handling

archival materials. The unit/partner/contractor shall provide gloves.

l. The Electronic Access Project Team/NARA staff shall have the right to inspect, without notice,

the unit/partner/contractor work areas and digitizing procedures or to be present at all times

when archival materials are being handled. Units/partners/contractors are encouraged to con-

sult the Electronic Access Project Team/NARA staff for clarification of these procedures or when

any difficulties or problems arise.

3. Training

a. Training may be provided by Preservation Programs, NWT, for archival material handling

and certification of unit/partner/contractor staff. Any new unit/partner/contractor staff as-

signed to this project after the start date shall be trained and certified before handling archival

materials.