DI-ALSS-81610

Scanning/Digitizing Data

Provides minimum scanning recommendations for responsible conversion of text, photographs, and graphic materials to achieve an acceptable level of image quality.

Approval DateJune 1, 2001

AMSC NumberG7440

Preparing Activity—

Project Number—

OPRG/DA12-TDM

DTIC Applicable—

GIDEP ApplicableNo

Limitation—

Applicable Forms—

Approval Limitation—

Form Version—

DID Formatdd_form_1664

963C CompliantNo

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

Supersedes

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Description & Purpose

Provides minimum scanning recommendations for responsible conversion and to achieve an acceptable level of image quality. The document addresses these formats: text, photographs, and graphic materials. As a rule, the key to quality scanning is to scan at the resolution that matches the information content of the original, not necessarily at the highest resolution possible. The scanning shall be provided to ensure a consistent and high quality image and decrease the likelihood of re-scanning.

Application & Interrelationship

This Data Item Description (DID) contains the format and preparation instructions for scanning documentation.

Use & Relationship

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Preparation Instructions

1Format.

1.1Use the original or first generation be used to achieve the best quality image.

1.2Types of Scanning:

1.2.1BitonalOne pixel representing black and white. Bitonal scanning is best suited to high-contrast documents such as printed text.

1.2.2GrayscaleMultiple bits per pixel representing shades of gray. Grayscale is suited to continuous tone documents such as black and white photographs.

1.2.3ColorMultiple bits per pixel representing color. Color scanning is suited to documents with color information.

1.3These three modes of scanning require some subjective decisions. Documents, including black and white test with color makes manuscripts, older printer matter, might be scanned in color to bring out special meaning or information identified through the color notation and markings. Although bitonal scanning is often used for type scanning as continuous tone in grayscale or color to being out the shade and conditions of the paper and the marks inscribed on it.

2Material formats.The following defines the minimum standards based on the following format types, text, photographs, maps, graphic material and three-dimensional material represented in two-dimensional format.

2.1Tonal depth: BitonalFormat: TIFF Compression: Uncompressed Spatial Resolution: 600dpi

2.2For handwritten or manuscripts that are difficult to read, consider providing a transcript of text using an Optical Character Reader (OCR).Consideration must be give to the cost of keying the transcription.

2.3Portable Document Format (PDF) shall be used as the format for creating and displaying text-based files on the web.The Adobe Acrobat viewer can be downloaded at no charge to view the documents.

2.4Since many digitization projects are undertaken to increase access, the digital image as a preservation copy is a natural by product.

2.5Consider current and future user needs, as well as the unique requirements of specific types of materials and collections.

2.6Scan at the highest resolution appropriate to the content of the original.

2.7Scan at a resolution level to avoid re-scanning in the future.

2.8Create and store master image, allowing for production of derivative images for current and future use.

2.9Create appropriate backup files and store media in an appropriate environment.

2.10Consider grayscale over bitonal, color over grayscale.

2.11Use objective measurements to determine scanner settings.Do NOT attempt to make the image look good on a particular monitor or use image processing to correct color.

2.12Do not compress digital masters, unless a lossless compression is used.

3Quality Control.A quality control program shall be conducted throughout all phases of the digital conversion process. Inspections of final digital image files should be incorporated into the project workflow. Typically, master image files are inspected via CD batch or online for a variety of defects. Depending on the project, the project can inspect 100% of the master images, or inspect a random selection of the files. A 10% sample is generally used. It is recommended that quality control procedures be implemented and documented and that specific defects found unacceptable in the image be defined. Images should be inspected while viewing at 1:1 pixel ratio or at 100% magnification or higher.

3.1Quality is evaluated both subjectively by project staff through visual inspection and objectively in the imaging software.The viewing environment for visual inspection of images is also important. Evaluation criteria for the visual inspection may include:

3.1.1Image is not the correct size

3.1.2Image is not the correct resolution

3.1.3File name is incorrect

3.1.4File format is incorrect

3.1.5Image is in incorrect mode, i.e. color image has been scaled as grayscale

3.1.6Loss of detail in highlights or shadows

3.1.7Excessive noise especially in dark areas of shadows

3.1.8Overall too light or too dark

3.1.9Uneven tonal values or flare

3.1.10Lack of sharpness/Excessive sharpening

3.1.11Pixalated

3.1.12Presence of digital artifacts, such as very regular, straight lines across picture

3.1.13Moire patterns (wavy lines or swirls, usually found in areas where there are repeated patterns)

3.1.14Image not cropped

3.1.15Image not rotated or backward

3.1.16Image skewed or not centered

3.1.17Incorrect color balance

3.1.18Image dull or not tonal variation

3.1.19Negative curve in the Look-up table

3.1.20Clipping black and white values (in histogram)

3.1.21CD recording and Verification

3.1.22File naming

References

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