Government of Canada Internet GuideGraphics EvaluationThis section provides guidance on using graphics. When you design and use graphics properly, you can make your Web pages easier and more pleasant to read. The most common graphic formats on the Internet are GIF and JPEG. GIF is often used for simple images composed of primary colours, while JPEG is best suited to photographs and more complex detailed images. Regardless of the format you use, you should consider the following issues. Colours: Colours for Web site graphics must follow Common Look and Feel Standard 6.5. Colour blindness: How will users with colour blindness see the graphic or page? Necessity: Is the graphic essential to understanding the text? Work required to produce a quality graphic: Does the graphic require manipulation, re-creation or resizing? Dimensions: Graphics should not exceed 590 x 472 pixels. Most current personal computer monitors display 640 x 480 pixels, but the default icons and status bars take up space. In inches, the graphic should not be more than 6 inches high and 5.5 inches wide. Transparent graphic: Should the graphic be transparent? Transparent graphics merge with the grey background of browsers, so there is no white space in and around the image. Aesthetically, it is usually best to make graphics transparent. However, graphics within the text of a document do not have to be transparent. Some applications allow the user to make graphics transparent. Interlaced graphic: Should the graphic be interlaced? Interlaced graphics are built gradually on the screen in five phases instead of all at once, so the user gets a "sneak preview" of what is coming. Newer browsers and most authoring tools support interlaced graphics. Use interlaced graphics sparingly, reserving the technique for large graphics that would otherwise take a relatively long time to download. User's download time: As graphics can increase download file size, it is best to minimize the size and number of graphics used on a page. Consider techniques to improve download time, such as non-interlaced graphics, reduced colour density and compression algorithms. Graphic name: What graphic file name will you use? Alternate text: For any graphic, you must always include an alternate text description for the visually impaired. See the Accessibility Standard 1.1 checkpoint in the Common Look and Feel Self-Assessment Guide. Alignment of text with graphic: Is there text to the right of the graphic that should be top-aligned, middle-aligned or bottom-aligned? Options for presenting graphics:
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