Procedure for digitizing images for screen display

by Robert Hershoff, 8/29/97

Introduction: the procedure for digitizing images from printed originals utilizes image scanning hardware and software to create a TIFF format digital file, which can be manipulated or edited using image enhancement software.

Image scanning software available: HP DeskScan 2.3 (in staff creativity lab and LIST office)

How to scan images:

1. Set up the DeskScan software:

a. The scanner should be warmed up:

The HP DeskScan software has a setting for faster scan versus warm up lamp before scanning. Use the Edit/Preferences/Image Quality = better illumination setting for best results.

b. Images should be placed in the center of the scanner bed:

The light source provides best illumination to the center of the platen

c. Type:

• Sharp B&W Photo (for any black and white, or grayscale image, including line drawings)
• Sharp Millions of Colors (for any image with color)

• Screen (check under the Custom menu, for Print Path. The screen setting should be 75 dpi, except for:
  
  
  • Black and White Newspaper photographic images, which should be scanned at 150 dpi, with the image placed on the scanner bed at a 45 degree angle
    
    
  • Maps and Line Art, which should be scanned at 600 dpi and adjusted using a special procedure
    
    Click here for more information on screen/print path settings

  2. Crop the image:

  • crop after the preliminary scan, then use the zoom feature before adjusting
  • include the caption
  • include a little white space on all four sides
  • check alignment (the corners should be square with the cropping tool) and adjust the placement of the document on the scanner if necessary

  3. Adjust Contrast, Color and Levels:

  Each scanner has its own color and contrast bias. Scanner software controls can be used to correct the bias and improve quality of the initial scan. Careful adjustment before scanning will substantially reduce image editing time in Photoshop.

  DeskScan II software settings:

  Tools / Color Adjustment:
  
  

  Saturation default = 50. Changing this setting to 40 removes the inaccurate red cast from sepia tone originals (on King Kong). The color adjustment may also be used to change the overall color balance of an image, if you want to intentionally alter the colors. Manipulate the distance and direction settings and observe the result.

  Tools / Highlight and Shadow:
  
  

  In DeskScan II, use the Tools / Highlight and Shadow adjustment to define the lightest and darkest points in each image.
  
  

  • Select the Highlight button and place the crosshairs on the lightest area within the image
  • Select the Shadow button and place the crosshairs on the darkest area within the image

  Use the Highlight and Shadow settings in place of the Brightness and Contrast adjustments. Adjustments to the brightness and contrast settings may adversely affect image quality. (This principle is also valid in Adobe Photoshop, where the Levels adjustments will usually provide a clearer image than the brightness/contrast adjustment.)
  
  The final scan will show superior contrast and definition.

  Tools / Emphasis Adjustment:
  
  

  For images with faded or exaggerated highlights and shadows, you can adjust the levels curve (similar to the Photoshop Image / Adjust / Levels feature) before scanning.

  Note: these settings are only active when their dialogue boxes are open. When you close the custom settings adjustment windows, the scanner reverts to default settings.

  4. Adjust image size:

  If you plan to use the image at a size larger or smaller than the original, adjust the image size before scanning. If you plan to create a full size image and a smaller, thumbnail version, scan at the largest size you need. Image quality deteriorates when files are resized in Photoshop, especially in the enlargement process.
  
  I consider 5 x 7 inches as the ideal size for full screen images. Any original image which is smaller is scanned at an enlargement ratio to approximate 5 x 7 inches; images larger than 5 x 7 inches are scanned at a reduction ration to create files with image dimensions approximating 5 x 7 inches. This procedure facilitates the preparation of images for screen display and seems to produce a better result (with smaller digital files) than resizing to enlarge the image in Adobe Photoshop.

  5. Scan the image

  • Save scanned images in .tiff 5.0 format
  For the Ronstadt project, please save files in f:\teams\shared\ronstadt

  Image files should be numbered consecutively. Assign numbers starting at the top left of the page, in the following order:
  top left, top right, bottom left, bottom right

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  Return to the Scanning and Conversions Page

  
  

  Updated 29 August 1997