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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. 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-

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  1. Digital Reformatting of Photographic Formats-2- Aaron Choate Digital Library Production Services The University of Texas Libraries

  2. Quality Control

  3. quality controlPrerequisites • Identify your products and goals

  4. quality controlPrerequisites • Agree on your standards • Determine a reference point • Understand the limitations of current knowledge, practice and technology

  5. quality controlSetting up your QC program • Identify Scope • Whole collection or a sample of images?

  6. 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

  7. quality control Setting up your QC program • Control the QC environment • Hardware configuration • Sufficient RAM • Fast enough processor • Large enough monitor • (CRT vs LCD)

  8. 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… )

  9. 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

  10. quality control Setting up your QC program • Control the QC environment • Color quality control instruments and software • Monitor calibrators • Densitometers • Colorimeters • …

  11. quality control Setting up your QC program • Control the QC environment • Color management

  12. 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)

  13. 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

  14. 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

  15. quality control Setting up your QC program • Codify your inspection procedures

  16. quality controlAssessing Image Quality • Evaluate: • Resolution

  17. 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?

  18. quality controlAssessing Image Quality • Evaluate: • Color and tone • Histograms • Avoid clipping • Color and Grayscale targets • Measuring RGB values

  19. 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

  20. 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?

  21. 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?

  22. 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?

  23. Examples:

  24. AAA – Spanish Colonial Arch. http://www.lib.utexas.edu/photodraw/missions/

  25. BLAC – Sanchez http://www.lib.utexas.edu/photodraw/sanchez/

  26. http://www.cah.utexas.edu/photojournalism/index.php CAH – Photojournalism & Am Pr

  27. http://runyon.lib.utexas.edu/ CAH – Robert Runyon

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