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Digital Reformatting of Photographic Formats -2-. Aaron Choate Digital Library Production Services The University of Texas Libraries. Quality Control. quality control Prerequisites. Identify your products and goals. quality control Prerequisites. Agree on your standards

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Digital reformatting of photographic formats 2

Digital Reformatting of Photographic Formats-2-

Aaron Choate

Digital Library Production Services

The University of Texas Libraries



Quality control prerequisites
quality controlPrerequisites

  • Identify your products and goals


Quality control prerequisites1
quality controlPrerequisites

  • Agree on your standards

  • Determine a reference point

  • Understand the limitations of current knowledge, practice and technology


Quality control setting up your qc program
quality controlSetting up your QC program

  • Identify Scope

    • Whole collection or a sample of images?


Quality control setting up your qc program1
quality controlSetting up your QC program

  • Determine methods

    • View the image at 100%

    • Use grayscale and color targets to evaluate color visually

    • Use histograms

    • Examine printouts


Quality control setting up your qc program2
quality control Setting up your QC program

  • Control the QC environment

    • Hardware configuration

      • Sufficient RAM

      • Fast enough processor

      • Large enough monitor

        • (CRT vs LCD)


Quality control setting up your qc program3
quality control Setting up your QC program

  • Control the QC environment

    • Image-display software

      • Choose a software package that is known to display images accurately

        • (Photoshop is a good bet… )


Quality control setting up your qc program4
quality control Setting up your QC program

  • Control the QC environment

    • Monitor set-up

      • Calibrate your monitors regularly

      • Gamma should be set to 2.2

      • White point temperature should be set to 5,000 kelvin (noon day sun)

    • Let the monitor warm up for at least 30 minutes

    • Reduce the room’s lighting levels if possible

    • Clean your screens …

    • Avoid turning the monitors on and off often if possible


Quality control setting up your qc program5
quality control Setting up your QC program

  • Control the QC environment

    • Color quality control instruments and software

      • Monitor calibrators

      • Densitometers

      • Colorimeters


Quality control setting up your qc program6
quality control Setting up your QC program

  • Control the QC environment

    • Color management


Quality control setting up your qc program7
quality control Setting up your QC program

  • Control the QC environment

    • Viewing conditions

      • Keep windows shaded

      • Reduce overhead lighting

      • Reduce glare on the monitors (face walls, not windows…)

      • Try to shield the viewing space for the original from the monitor

      • Inspect images against a neutral gray background (turn off your desktop patterns)


Quality control setting up your qc program8
quality control Setting up your QC program

  • Control the QC environment

    • Human characteristics

      • Because each person sees color differently, it would be ideal to have one person do all the QC for a batch of images.

      • Otherwise, come up with an effective way to communicate about color


Quality control setting up your qc program9
quality control Setting up your QC program

  • Evaluate system performance

    • System tests prior to conversion –

      • Resolution

      • Linearity (dynamic range)

      • Flare

      • Scanner noise

      • Artifacts

      • Color reproduction


Quality control setting up your qc program10
quality control Setting up your QC program

  • Codify your inspection procedures


Quality control assessing image quality
quality controlAssessing Image Quality

  • Evaluate:

    • Resolution


Questions to ask
Questions to ask

  • Is the stroke adequately reproduced?

  • Is the significant detail adequately reproduced?

  • Is fine detail in the darkest and lightest portions retained?

  • Are there even gradations across the image?

  • Is the image free of moire effect?

  • Is the significant informational content adequately reproduced?

  • Is the document fully reproduced?

  • Is the image too light or too dark?


Quality control assessing image quality1
quality controlAssessing Image Quality

  • Evaluate:

    • Color and tone

      • Histograms

        • Avoid clipping

      • Color and Grayscale targets

      • Measuring RGB values


Tips

  • Decide on whether you want to include the target in every image or if you want to image the target once during a scanning session

  • Choose a place in the scan range that will maximize your ability to capture data

  • Replace your targets on a regular basis

  • Sample scans of targets should be captured with your project metadata


Questions grayscale
Questions … grayscale

  • Are the details in the sections of the document captured?

  • Is the image too light or too dark overall?

  • Use your grayscale bar to test:

    • How many bars can you identify?

    • Where do you cease to discern distinct shades

    • Do you see a color shift?

    • How do the RGB values compare to the reference values?

    • Are all digital levels (0 – 255) used? Is there any clipping?


Questions color
Questions … color

  • Do you observe a color shift?

  • Is the image light or dark overall?

  • Compare the grayscale values as before.

  • Compare the color values to the color target.

  • Is the color satisfactory?


Quality control assessing image quality2
quality controlAssessing Image Quality

  • Evaluate:

    • Overall evaluation

      • Does the image convey all of the significant information

      • How would you rate the image as compared to the original? (unacceptable, adequate but diminished, comparable, improved)

      • Will the potential user be satisfied with the image as a surrogate?

      • Is the image’s dynamic range adequate?

      • Are you satisfied with the color appearance?



Aaa spanish colonial arch
AAA – Spanish Colonial Arch.

http://www.lib.utexas.edu/photodraw/missions/


Blac sanchez
BLAC – Sanchez

http://www.lib.utexas.edu/photodraw/sanchez/



Cah robert runyon

http://runyon.lib.utexas.edu/

CAH – Robert Runyon


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