Scanning and Working with Digital Images: Beyond the Basics

The following information applies to flatbed scanners and Adobe Photoshop, and is meant to familiarize users with common commands and tools in various systems.

Flatbed Scanners

You will want to scan your original in one of the following modes depending on the image:

  • Line Art: Black and white only. No grays involved.
  • Gray Scale: Continuous tone black and white artwork. Allows for grays.
  • Halftone: Previously published original made up of dots (moire pattern). You may have a descreen option here. Can be color or black and white.
  • RGB: Red/green/blue additive color mode (if your final output to screen only).
  • CMYK: Cyan/Magenta/Yellow/Black color mode (final output to print).

1. A Preview Scan is the first command you want to execute to check your scan settings. You will also want to choose:

  • Physical Size of Original (dimensions)
  • Physical Size of Scan (dimensions) and Resolution

2. Often there is an Auto-Adjust option that will set your tonal values.

Adobe Photoshop Basics
  • Gamma correction: Increasing the brightness of midtones without affecting highlights and shadows.
  • Histogram Plot: Shows brightness distribution of image. To adjust, drag triangular handles: black for shadows, gray for midtones, white for highlights.
  • Tone Curve: Moving the curve up will lighten the middle tones and vice versa. Descreening/Removing Moire Pattern: If your original comes from a newspaper or magazine, there will be a dot screen to remove. Blurring an image usually removes this. See Filtering.
  • Filtering an Image: Useful for low/high contrast pictures. You can soften the image by blurring or sharpen edges by sharpening.
  • Resizing and resampling Images: When you resize and want to retain the same resolution, leave on “resample image”. If you just change the paper size without re-sampling, the dpi count is multiplied.
Other Common Software

Photo Explorer, MS Picture It!, Corel Photo House, etc

Tips for Preparing Materials for Posters
  • In anticipation of the Academy and ARVO poster rushes each year, Media Services has formulated guidelines to assist individuals in preparing materials for submission to Media Services. To insure faster turnaround time for your poster, please be sure to get your materials into Media Services as early as possible since posters will be worked on in the order they are received. Submission deadlines are posted several weeks ahead of time.
  • All posters are created in Quark Express for Macintosh, therefore, please be sure to save the following components of your poster as follows:
  • A hardcopy of all poster text is required along with any additional supporting material.
  • Text: The preferred format for text is MS Word (Note: not the same as Wordperfect). If your computer does not have Word, please be sure to save it as a text only file (txt). To insure an eye-catching poster, please try to keep your text to a minimum and be sure to add a lot of graphics and charts!
  • Photos or images of any kind should be saved as an EPS (.eps) file which is preferable since it guarantees a more accurate printout of your image. If you cannot save your image as an EPS, you can save it as either a TIF or JPEG file (tif, jpg). Please keep in mind that images should be scanned at a minimum of 300 DPI in order to insure the best possible quality.
  • You may also provide Media Services with slides or flat artwork which we will scan for you.
  • Tables and charts should be created in Powerpoint manually without using the autochart feature (since this causes problems) and then saved as a JPEG (.jpg). Charts created in Excel or MS Word have to be reconfigured by Media Services.
  • Colors: Posters are printed out in full color, 300 dpi at 40″x60″. If you have additional poster material that you would prefer to have tacked onto the poster, please let the staff know ahead of time and we will be sure to include open space for your work.
Powerpoint Slides

Powerpoint presentations can be saved in PPT or PPTX for PCs and in the ’98 version for Macintosh. It is recommended that you save your file in the most recent version of Powerpoint since occasionally changes can occur in backgrounds and symbols when converting to a higher version inhouse after you have dropped off your file. You may save your file on a flash drive when dropping off files for processing into slides. Requestors also have the option of emailing their presentation to the Media Staff folder (type Media Staff in the name section of your email). Please be sure to also send a reminder email to either Bred Boudi to let us know to look for your file.

Images Used in Powerpoint Presentation

For those wishing to incorporate digital images into their Powerpoint presentation, the Media Staff recommends the following formats:

  • Macintosh Powerpoint 2004: PICT; PNG, JPEG
  • PC with Powerpoint: PNG, JPEG, GIF
Other Graphic Program Compatibility Questions

Please consult Media Services staff when attempting to incorporate other graphics program files such as Canvas into your presentations. Occasionally problems arise in file size and compatibility. If possible, save your image file as an EPS or TIF file to insure that it can be opened in Photoshop. This will allow for a translation into many different file types. If scanning your own images to be used in Powerpoint, please be sure to keep in mind that unless you are planning to print out the image at a high resolution, it is not necessary to scan at anything higher than 72 DPI. This is due to the fact that standard monitors will not be able to show images higher than 72 DPI, even if the original was scanned at a higher resolution.


Introduction to Digital Imaging

If you’re reading this, you’re obviously interested in digital imaging in at least some of its myriad forms.

This tipsheet is meant to get you started, help you understand jargon, realize the possibilities, think about considerations and point you in the right direction. There are also separate tipsheets for:

  • Digital Imaging Terminology
  • Digital Cameras Introduction and Terminology
  • Scanning and Working with Digital Images: Beyond the Basics
How can you capture digital images or where can you get them?


  • Flatbed (for flat artwork, pictures, etc.)
  • Transparency (for slides and negatives)
    Note: If you scan the images yourself, there may be some color correcting to do.

Photo CDs/Picture CDs (Kodak Photo CDs are already recorded and CD-Rs you can burn):

  • Local photo retailers often offer CD services along with processing.
  • Digital cameras/camcorders (See resources below)
  • Free off the web (See resources below)
How can you use digital images?
  • To enhance websites
  • To send photos to your friends/family over the Internet
  • In electronic presentations and in printed materials

When getting ready to make a digital image, consider “What is its end use?” The answer to this question will dictate how you create the image and save it.

What are the steps in the digital process?
  • Acquire a good image (See “How can you capture digital images?”)
  • Select storage medium (memory sticks, smart media, hard drives, flash pix, CD-R, CD-RW)
  • Inventory images (See Image catalogers in definitions)
  • Edit images with output in mind (See output information)
  • Save in appropriate file formats (See file formats)
  • Back up your files
How do I send/view pictures via email?
  • Be aware which platform the recipient is using. PCs require a tagline at the end of each file, whereas Macs do not. (eg, photos .jpg, .gif)
    Cross-platforming can still be problematic, however.
  • Send images at 72 dpi, probably saved as a jpeg medium quality. (See file formats for more information.) Depending on your image source, you may have to resize/resave your image. Be sure to save as 8-bit/indexed color.
  • AOL is notorious for having problems sending pictures over the Internet. Consult your Internet Service Provider (ISP) if you are having difficulties.
Output Information (How large should I scan my files?)
  • www images: Use the same settings as for emailing images.
  • Desktop publishing: Consult the graphic designer at the publication for more information. Some standard resolutions are:
  • 150 dpi: Images up to 4″x6″ produced in black and white on newsprint or for non-glossy newsletters.
  • 300 dpi: Images up to 5″x7″ produced in color for glossy stock.
  • Personal Use: Decide based on available memory and storage medium.
  • Enlargements: Choose based on personal use requirements and the size of enlargements. Once you get close to 8″x10″ reproductions from a 35mm original, expect to lose quality.
Before You Buy
  • Research current products (see resources below).
  • Decide how much you want to spend.
  • Realize prices are coming down fast and some technology is becoming obsolete.
  • Consider how you want to use the technology and learn more about it.
  • Consider whether you should buy a digital camera (more expensive but all your images are originally digital) or a scanner (less expensive but must scan pictures individually).

Digital Imaging Terminology

File Formats
When you create/use a digital image, it will be saved as a file format. Several are listed below, with their purposes, origins and capabilities.
Note: Powerpoint presentations require jpeg images for best results.


Mac vs. Windows Formats

  • PICT: Macintosh standard format.
  • BMP: Windows standard format. Pronounced “b-m-p.” Device-independent bitmap that allows image to display on any device. Comes in 2 formats: RGB encoded (not compressed, supports 8-bit color) and RLE encoded (lossless compression, 8-bit color). Not to be confused with “bitmap” in reference to a black-and-white image as saved in Photoshop.

Commonly Used Web Formats

  • GIF (graphic interchange format): Pronounced “jiff.” Most common format for web graphics. Ideal for simple graphics. Uses LZW (see below) Interlaced gifs are good for large illustrations while conventional gifs are good for navigation buttons and icons. You can use transparent gifs with caution.
  • PNG (portable network graphics): Pronounced “ping.” New file format with embedded text, lossless compression, 48-bit color depth, interlacing, automatic gamma correction. Supported by Microsoft Internet Explorer and Netscape Navigator.
  • JPEG: Joint photographic experts group): 24-bit color images. Most commonly used format for displaying color photographs. Uses lossy compression at high, medium and low quality. Uses .jpg extension.

Commonly Used Desktop Publishing Formats

  • EPS (encapsulated postscript): Good for outputting files for printing, especially charts and graphs.
  • TIFF (Tagged image file format): Widely supported format used commonly in desktop publishing. Can support 24-bit color. Variations of the format, called extensions, sometimes make it difficult to open a file from another source. Can use LSW or other lossless compression.

Other Formats

  • PCD: Kodak Photo CD format. Have slides/negatives scanned onto CDs at local photofinisher or service bureau. Results in high quality still superior to most digital cameras.
  • FPX: Flashpix format. Stored in multiple resolutions for quicker editing and display. Preferred by photographers for high resolution images.
  • PDD/PSD: Adobe Photo Deluxe and Photoshop formats. Can retrieve layers and changes made within these software programs.

Many scanners/cameras come with their own file format based on their software. Check the program to make sure you can either manipulate the image within the program or export it to another program where you can manipulate it.

  • The reduction in size of a file image. Different file formats use different compression types.
  • Lossy Compression: As in jpeg images. Image loses quality with compression and doesn’t regain it. Medium quality good for images; high quality good for images with text.
  • Lossless Compression:As in tiff or gif images. Image doesn’t lose quality with compression and reopening. See also LZW compression.
  • LZW Compression: Best at compressing images with large fields of homogeneous color. Less efficient for complicated pictures with many colors/textures. Doesn’t lose data or distort image. Images with fewer colors will compress more efficiently.
Image/Color Information


Interpolation: Interpolated resolution adds pixels to the image using software to determine what color they should be. It is important to note that interpolation doesn’t add any new information to the image, it just makes it bigger.

  • Gamma: Degree of contrast between midlevel grays of an image.
  • Resolution: The quality of any digital image depends in part on its resolution and the number of pixels used to create the image. More and smaller pixels add detail and sharpen edges.
    • dpi (dots per inch)
    • ppi (pixels per inch)


  • Indexed Color: Most common model for the web because files are the smallest. (8-bit)
  • RGB (red, green, blue): Color model used for video displays and recording images via digital camera. Additive color combines the 3 colors to make white. (24-bit color)
  • CMYK (cyan,magenta,yellow,black): Color model used for printing. Subtractive colors.
  • Pixels: Short for picture element. Represents a point at an x/y coordinate
  • Color depth: (expressed in bits) how much memory is assigned to each pixel, based on how much color can be viewed on a monitor. Based on VRAM (Video RAM)
    • 1 bit: black or white (0 or 1)
  • 8bit: Each pixel has 8 bits of memory expressed as 1 of 256 colors. Common in older computers or laptops; referred to as “8 bit” or “256-color” display. However, “browser safe” color management is based on 8-bit, 216 color.
  • 16 bit: Thousands of colors.
  • 24 bit: Can display millions of colors. Referred to as “True color.”
  • Dithering: Method of reducing color range of images down to 8-bit or fewer colors. Causes loss of tone and image detail.
  • Anti-aliasing: Improving the look of screen images by softening jagged pixel edges. See Vector graphics/raster images, Vector graphics: (draw or Postscript graphics) illustrations made of lines/shapes. Usually created in a drawing program like Corel Draw or Illustrator.
  • Raster images (bitmap or paint images): Convert vector graphics to this format for the web. Any illustrations imported into this format automatically are anti-aliased and can be easily resized.