Scanning and Printing
XGeneral Guidelines for Scanning
Although there are numerous types of scanners, some basic principles that are applicable in most scanning situations. Scaling and resolution must be set at the time the image is scanned. The input settings draw reference from the original image producing the best quality scans. A common mistake is to allow the photo-imaging software to automatically set the final size (scaling) and resolution, which may force interpolation to occur and degrade the final image. Select the appropriate resolution based on the intended use.
Scanning Resolution
  • Internet-----------------72 dpi
  • Newspaper---------- 150 dpi
  • Glossy Magazine ---300 dpi
  • Photo-quality print --300 dpi
Determining the best resolution for continuous tone prints is based on the maximum dpi of the printer being used. Good scanning software will allow a user to input a scaling factor into a dialog box and then do the file size math automatically. If your software does not do this, use the simple formula in box 7.2 to calculate input resolution based on printer resolution and the scaling of the image. For example, using a 300 dpi printer one will need to scale a 4 x 5 inch print at 400 percent to make a 16 x 20 inch digital print, requiring an input resolution of 1200 dpi.
Scanning Steps
  1. Open the scanning software. Often this can be done through imaging software, under File>Import>Name of the scanning software. Many scanners use an independent software application to drive the scanner. In this case, open the independent application and proceed to the next step.
  2. Set the scanner for Positive or Negative. Many scanners are dual use, with the ability to scan photographic positives (reflective) and negatives or slides (transparent). Make sure the scanner is properly physically configured for reflective or transparent materials and set to the proper media before scanning.
  3. Grayscale or Color. Even though scanning in grayscale is possible, scanning in color often provides superior results because the scan is occurring in three channels (red, green, and blue) instead of one. If black and white is desired, simply change the image to grayscale in the imaging software after it is acquired.
  4. Place the image/negative or object in the scanning bed. For flat artwork, be sure to place the image squarely on the scanning bed as this will reduce the amount of post-scanning scaling and rotating.
  5. Perform a preview scan of the entire scanning bed. This will allow you to see the entire scanning area and the image to be scanned. Use the marquee tool to select the target area as closely as possible.
  6. Make tonal adjustments. Most good scanning software will create a preview of the image based on the area you selected with the marquee tool. All-scanning software has settings to control the contrast, brightness, and color balance of images. Change these settings to get the previewed image color balanced as closely as possible before scanning. The most important adjustment to make is contrast. An image that has excess contrast contains less information about tonal values. Slightly flat contrast images contain more information in the highlight and shadows and generally provide better results in post-scan processing. After scanning use your photo-editing software to make final color and contrast adjustments to an image.
  7. One important adjustment to make first is contrast using the scanning software, if possible. An image that has excess contrast contains less information about tonal values. Flat contrast images contain more information in the highlight and shadows. Generally these post-scan adjustments to contrast, color and brightness assures capturing more data for better final results. It is good practice to make all image corrections first with the scanning software before saving the file. Only rely on your photo-editing software to tweak and make final corrections because after the scan any changes to the file only throws away data. It is always best to get it right in the scan from the start.
  8. Set File Size. Before scanning, decide what size your final print is going to be. Scanners display and define size in two ways, image size and resolution. Most scanning software will display the size of the area being scanned, multiplied by a scaling factor. Increasing the scale of the image will increase the dimensions of the final scanned image. Increasing the resolution of the scan will increase the potential quality of the image. Both operations will increase the file size. As a general rule the larger the file size, the more options you have in working with the finished scanned image.
  9. Scan Image.
  10. Save file. Once your image is scanned immediately save the file. Keep these scans safe and work only with copies of these images.