Graphics, Part II: Scanning

Capturing Images

• A scanner is a device much like a fax machine or a photocopier
• Converts a paper image (or 3D object!) into digital form
  • Line by line
    • Reads the image one pixel-sized line at a time and converts it to a screen image
• Once in the computer, each of those pixels may be manipulated--allowing for endless creative potential

Scanning in Fireworks: Step-by-Step

1. Select File Menu, then Scan, and then Twain Acquire. "Twain Select" must also be chosen the very first time a particular computer tries to scan.
   
   This starts the software that controls the scanner--allowing you to make several settings.
2. Each scanner's software looks different, but you should be able to do certain standard settings of resolution and scanning mode (e.g., color vs. black and white).
   
   1. Resolution (Dots Per Inch or DPI).
      • Choose 72 dpi if going straight to the Web; or a higher resolution if you're going to manipulate it.
      • Anything over 300 is exessive.
   2. Scanning Mode (Bit Depth).
      
      • Number of colors:
        1. Color - Full = millions colors
        2. Color - 256 (through 8)
        3. Gray - 256 (through 4)
        4. Line Art = 2 colors (black and white)
   3. Descreen (not available on all scanners).
   • Use Descreen only if your original is a photographic image from a newspaper, magazine or book.
   • It prevents a distortion (a moire pattern) that occurs when scanning a previously printed image.
3. Select Preview to check the orientation of the original on the scanner.
   
   • A preliminary version of the scan appears.
   • Adjust the selection markers (the little dotted lines) to crop the image.
4. Scan it by clicking on the Acquire or Scan button.
5. Close scanning software in order to return to Fireworks.
6. Manipulate it as you will!
7. Save it in either Fireworks PNG format or export it to GIF or JPEG format.
   • Filename conventions:
     • End with an extension: .png, .gif, .jpg or .jpeg
     • No spaces!
     • Use lowercase. Makes it easier to use files on a Unix system (e.g., bama.ua.edu)

A Word About Moiré Patterns

1. Descreen
• Not available on all scanners, but many do have this option.
• Use Descreen only if your original is a photographic image from a newspaper, magazine or book.
• The image above when scanned with Descreen selected:
  
2. If you're using a scanner without a Descreen option, there are some techniques in Adobe Photoshop that may eliminate moiré patterns. (I haven't tried this out in Fireworks.)
• Lynda Weinman suggests (pp. 328-9):
  1. Scan the image at a higher resolution than 72 dpi. Try, for example, 150.
     • Sometimes this alone will fix the problem. See the above photo at 150 dpi. But not in this case...
  2. Using Photoshop, go to the Filter menu, select Blur and then, specifically, Gaussian Blur.
     • Set Radius to 1.2 pixels--although you may need to set this higher, depending on how it looks.
     • The moiré pattern almost disappears--as you can see here. But the image is blurred.
  3. Reducing the image size will also reduce the blurriness, but it's still not as sharp as the image above.
     
  4. From the Filter menu, select Sharpen, and then Sharpen again (or Unsharp Mask--which allows for variable sharpening of the image). Voila! A good-looking image with no moiré pattern:
     

Exercises:

1. Scan an image at 300 dpi. Save as test300.jpg.
2. Scan an image at 72 dpi. Save as test72.jpg.
3. Scan an image in maximum number of colors (highest bit depth). Save as testbd.jpg.
4. Scan an image in greyscale. Save as testgs.jpg.
5. Scan a photograph from a magazine at 200 dpi and do not use Descreen. Save as test200nds.jpg.
6. Scan a photograph from a magazine at 200 dpi and do use Descreen. Save as test200ds.jpg.
7. Scan a photograph from a magazine at 72 dpi and do not use Descreen. Save as test72nds.jpg.