Using images: Select the correct file format and use the proper size

When working with images for PowerPoint, Web, or print use, there are three common graphics file formats to use: GIF, JPEG, and TIFF. GIF and JPEG (or JPG) are the standard formats for Web pages and slide show use. Other formats (e.g., PNG, JPEG 2000 and SVG) have been developed and may grow in use. TIFF is a standard format for high-resolution printing from desktop publishing or word processing applications.

Format descriptions

GIF (Graphics Interchange Format) - used for images that are made up of 256 or fewer colors with large areas of the same color such as logos, some computer screen captures, line drawings, text headings, etc. Do not use the GIF format for images that have gradations in color or for photographs. This format compresses the file for the smallest possible file size.

The GIF format also supports transparency and animation. A transparent GIF image creates the effect that your image has an irregular outline. One color of your image is made “transparent” so the background shows through. Animated GIF images are several individual GIF images that have been put together using special software that combines the images to create the animation.

JPEG (Joint Photographic Experts Group) - used for color photographs or artwork with lots of colors and gradations that will be placed on Web pages and in computer slide shows. This format uses compression to shrink a file size while maintaining image quality. The JPEG format reduces the file size by eliminating information. Each time a JPEG file is saved, more information is thrown out. Do this too many times, and little information will remain in the file resulting in a very poor quality image.

TIFF (Tagged Image File Format) - most commonly used to place photographs and graphics in page layout applications (desktop publishing) or word processors. TIFF produces large file sizes as it preserves a high-quality image. Most applications can read TIFF file formats; however, there are several different “flavors” of TIFFs. If you have a problem with a TIFF file, Adobe Photoshop can resave the file into a TIFF version that most programs can use.

EPS (Encapsulated Post Script) - a standard format for high-resolution printing. However, EPS was created for postscript printers, is more difficult to work with, and EPS-formatted images most likely will not work in word processors (Microsoft Word or Corel WordPerfect).

Working with images for PowerPoint or Web use

When working with images for PowerPoint or Web use, there are two basic image editing processes you will use: crop an image to select a part of the image that you want to use and/or resize an image to make it smaller.

Always edit your images in an image editing program. Good programs for image editing include Adobe Photoshop, Adobe Photoshop Elements, and IrfanView. Please see the appropriate page for basic editing instructions (Adobe Photoshop & Photoshop Elements or IrfanView).

Follow these guidelines for effective use of images in PowerPoint or on Web pages.

• Do NOT use a photo image in the original size created by the camera. You can “downsize” an image and still have a high-quality image for slide show or Web use. For example, a test PowerPoint file with one slide containing a photo image at the original size of 2560x1920 pixels is 1.08MB. The PowerPoint file with the same photo image reduced to 1280x960 size is 314KB — around 1/3 the size. (For more information on working with image size and resolution, please see the video “Explanation of digital images - picture resolution and size” found on the Tips for Effective Presentations page.)
• If you have a JPEG image that needs editing, convert it to the TIFF format and edit the TIFF version. The JPEG format uses compression to shrink file size while maintaining image quality. Each time a JPEG file is saved, more information is thrown out and the image quality degrades.
• In PowerPoint, all images must be inserted directly through the Insert - Picture - From File command. If you copy-and-paste an image, you may corrupt your file. The corruption may not occur on the page the image is located and you may not know the file is corrupted until you try to send it to slides, to a printer or rework or use the file later on.
• PowerPoint will allow you to insert TIFF files, but this will create a PPT file that is much larger and the slide show will run more slowly. Use the JPEG, GIF, or Microsoft proprietary EMF format.
• Do NOT “stretch” or “shrink” the image in Dreamweaver or other Web page editor — create an image file with the pixel dimensions needed. For example, if you want a thumbnail image of a picture on the page, you should create a second image file with smaller pixel dimensions (e.g., 50 pixels wide).
• Do NOT resize or crop the image within PowerPoint as you will simply have a smaller view of the original file. Creating a separate, smaller JPEG image file to insert into PowerPoint will allow your slide show to run more quickly.

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Bonus: Free photos

If you don't have the right photograph, try one of these sites.

IANR News Photo Gallery - copyrighted photos intended for use by news media and University of Nebraska-Lincoln faculty and staff

USDA Photography Center - photography depicting general agriculture, health, economics, resource conservation, forestry, and other programs administered by the agencies of the Department of Agriculture. These images are in the public domain.

USDA Agricultural Research Service Image Gallery - provided by the Information Staff as a complimentary source of high quality digital photographs. These images are in the public domain.

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 Institute of Agriculture and Natural Resources (IANR)
 University of Nebraska-Lincoln
 Last updated March 9, 2007