Standard: Graphic Formats
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Definitions
A graphic is an image, including photos, logos, banners, icons, maps, charts (including bar charts, pie charts, flow charts and organizational charts), graphs and other images.
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Content requirements
- Use only the GIF (.gif) or JPEG (jpg) format for graphics.
- Do not use other formats, such as PNG.
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How to
GIF and JPEG are the two standard Web formats. Regardless of the format or complexity of the original image, saving in one of these formats will typically yield a small file size with little visual degradation. GIF and JPEG both produce good Web graphics, but each is better at compressing specific types of images.
GIF: best for images with large amounts of a single color, lines, and no shading or graduated colors. For example: line art, graphs, drawn logos. GIF is limited to 256 colors, one of which (usually the image's background color) can be made transparent. Using fewer colors when creating a GIF file from an image will make the file smaller. If a file saved as GIF has color banding or the color looks "blocky" or if the file size is unexpectedly large, try saving it as JPEG.
JPEG: best for images with shading or graduated colors and no sharp lines. For example: photographs and paintings. JPEG can have as many colors as the computer can display, typically in the millions. If a file saved as JPEG has unexpected colors in areas that should be one color, or if fine lines or text lines are blurry, try saving it again (from the original image) at less compression or save it as a GIF.
For images that combine photographs and text, try both formats with different settings (numbers of colors for GIF, % quality with JPEG) to see which yields the smallest file with the least visual degradation.
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Rationale
GIF and JPEG are the standard Web formats. PNG and other formats don't appear in most Web browsers without additional software or browser plug-ins. Use those formats as original files, but export them to GIF or JPG for use on the Web site.
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Related governance documents
EPA
Related Policies
Related Procedures
Related Standards
Related Guidance
Non-EPA
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Full Metadata about this standard
Name Graphic Formats
Tracking number NT00000000
Type Standard
Required or Recommended Required
Effective date 09/28/2005
Date approved 09/28/2005
Category File Formats, Graphics and Multimedia
Web Council review by 09/05/2008 (or earlier if deemed necessary by the Web Council)
Governing Policy Web Governance and Management (PDF) (4 pp, 339K, About PDF)
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