Article ID: 320314 - View products that this article applies to.
This article was previously published under Q320314
For a Microsoft PowerPoint 2000 version of this article, see 272399
This article discusses the following topics:
For more information about the graphics file types that your Microsoft Office 2003 product can use, click Microsoft product Help on the Help menu, type graphics file types in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.
For more information about the graphics file types that your Microsoft Office 2007 product can use, click the Microsoft Office Product Help button, type graphics file types in the search field, and then click Search to view the topics returned.
This article is divided into the following sections:
Picture formats: Raster pictures
BMP: Windows bitmapWindows bitmaps store a single raster image in any color depth, from black-and-white to 24-bit color. The Windows bitmap file format is compatible with other Microsoft Windows programs. It does not support file compression and is not suitable for Web pages.
Overall, the disadvantages of the Windows bitmap file format outweigh the advantages. For images of photographic quality, use a PNG file, a JPEG file, or a TIFF file. BMP files are suitable for wallpaper in Windows.
PCX: PC PaintbrushImportant The PCX file format is only supported in the 2003 Office system. It is not supported in the 2007 Office system or later versions of the Office system.
PC Paintbrush pictures, also called Z-Soft bitmaps, store a single raster image at any color depth. Paintbrush pictures are more widely used in earlier Windows programs and MS-DOS-based programs. Paintbrush pictures are compatible with many later programs. PCX pictures support Run Length Encoded (RLE) internal compression.
PNG: Portable network graphicsPNG pictures store a single raster image at any color depth. PNG is a platform-independent format.
JPEG: Joint Photographic Experts GroupJPEG pictures store a single raster image in 24-bit color. JPEG is a platform-independent format that supports the highest levels of compression; however, this compression is lossy. Progressive JPEG files support interlacing.
The level of JPEG file compression can be increased or decreased. However, image quality is sacrificed for file size. The compression ratio can be as high as 100:1. (The JPEG format comfortably compresses files at a 10:1 to 20:1 ratio, with little picture degradation.) JPEG compression works well with photo-realistic artwork. However, for simpler artwork with fewer colors, sharp levels of contrast, solid borders, or large solid areas of color, JPEG compression does not provide superior results. Sometimes the compression ratio is as low as 5:1, with a high loss of picture integrity. This loss occurs because the JPEG compression scheme compresses similar hues well. But the JPEG compression scheme does not work as well with sharp differences in brightness or with solid areas of color.
GIF: Graphics Interchange FormatGIF pictures store single raster image data or multiple raster image data in 8-bits, or 256 colors. GIF pictures support transparency, compression, interlacing, and multiple-image pictures (animated GIFs).
GIF transparency is not alpha channel transparency and cannot support semitransparent effects. GIF compression is LZW compression, at a roughly 3:1 ratio. Animated GIFs are supported in the GIF89a version of the GIF file specification.
TIFF: Tagged Image File FormatTIFF pictures store a single raster image at any color depth. TIFF is arguably the most widely supported graphics file format in the printing industry. TIFF supports optional compression and is not suitable for viewing in Web browsers.
The TIFF format is an extensible format. This means that a programmer can modify the original specification to add functionality or to meet specific needs. Modifying the specification can lead to incompatibilities between different types of TIFF pictures.
Picture formats: Vector pictures
DXF: AutoCAD Drawing Interchange FileThe DXF format is a vector-based, ASCII format that the Autodesk AutoCAD program uses. AutoCAD provides highly detailed schematics that are completely scalable.
CGM: Computer Graphics MetafileThe CGM metafile can contain vector information and bitmap information. It is an internationally standardized file format that is used by many organizations and government agencies, including the British Standards Institute (BSI), the American National Standards Institute (ANSI), and the United States Department of Defense.
Note In Office 2007, the CGM graphics file format requires a graphics filter.
CDR: CorelDRAW!The CorelDRAW! metafile can contain both vector information and bitmap information.
Note In Office 2007, the CDR graphics file format requires a graphics filter.
WMF: Windows MetafileThe Windows Metafile is a 16-bit metafile format that can contain both vector information and bitmap information. It is optimized for the Windows operating system.
EPS: Encapsulated PostScriptThe Encapsulated PostScript format is a proprietary, printer description language that can describe both vector information and bitmap information.
Note In Office 2007, the EPS graphics file format requires a graphics filter.
EMF: Enhanced MetafileThe Enhanced Metafile format is a 32-bit format that can contain both vector information and bitmap information. This format is an improvement over the Windows Metafile Format and contains extended features, such as the following:
PICT: Macintosh PictureThe PICT file is a 32-bit metafile format for the Macintosh computer. PICT files use Run Length Encoded (RLE) internal compression, which works reasonably well. PICT files support JPEG compression if QuickTime is installed (Macintosh only).
Note In Office 2007, the PICT graphics file format requires a graphics filter.
Resolution and color depthThis section discusses the appropriate color depth and resolution for raster pictures. If you save pictures with the correct resolution and color settings, you create smaller files. Smaller files mean smaller, faster documents and presentations. It is in your best interest to make a picture as small as possible, within the requirements of your picture usage.
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Note Microsoft recommends a resolution of 72 pixels per inch, because most monitors have between 60 pixels and 80 pixels per inch. Saving at a higher resolution does not result in a higher-quality display, because your monitor cannot display more pixels than physically exist in the monitor. You should calculate the points per inch according to the completed size of your picture, not the original size. For example, if you are scanning an 8.5-by-2-inch letterhead for use on a Web page with a completed width of 2 inches, you can scan at 72 ppi for 2 inches, for a total of 144 pixels. The resulting file looks great when it is sized to 2 inches and is displayed on a monitor.
*Note At 256 colors, JPEG files offer a higher level of compression than GIF files do. However, JPEG compression does not compress some simple files as effectively as GIF compression does.
Printed outputHow to create good printed output is a complex subject, because of the vast number of printers that are available and the capability of each printer to produce color output and grayscale output. The primary factor for good printed output is the number of lines per inch (LPI) that your printer is capable of printing.
To print in color or grayscale, a printer must print in halftones. Halftones are arrays of dots that are arranged in a grid and that represent each image pixel as a shade of gray. For a dark gray, most of the dots in the grid are filled in. For a light gray, only a few dots on the grid are filled in. The LPI setting for the printer determines the size of this grid. The higher the LPI, the smaller the grid, and the fewer shades of gray the printer can render.
To print in color, the printer must print overlapping lines of colored dots. Each dot is set at a different angle from the other dots and is slightly offset, so that the dots do not completely cover each other. This measurement is known as the Screen Frequency and is represented in degrees of rotation of the lines of dots that make up that color.
The following table helps you to choose the optimum resolution for scanning, in dots per inch (dpi).
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To calculate your target scanning resolution, you can multiply the LPI of your printer by two. This is a general rule. To find out the LPI of your printer, see your printer documentation.
Note You must experiment when you apply the general rule of multiplying the LPI by two. Some printers support very high resolutions. If you save your picture at more than 300 ppi, larger pictures may take up large amounts of disk space and may slow down other operations on your computer. Multiple large pictures in a document can cause a program to stop responding or can cause Windows to stop responding.
The only exception to this rule is pure black-and-white images, or "line art" images. These images use 1 bit to store color information. Scan these images at a 1-to-1 ratio. If you have a 600 dpi printer, scan these images at 600 ppi in Line Art mode.
If you want your picture to be in grayscale or to have fewer than 256 colors, use either the TIFF format or the GIF format. The TIFF format is the standard of the printing industry for graphics, because the TIFF format does not use a lossy compression scheme. Other formats, such as JPEG, use a lossy compression scheme. TIFF also supports multiple levels of transparency, which few other formats do.
If the picture has more than 256 colors, save the picture in the TIFF format or the PNG format. Microsoft recommends the PNG format if you want transparency. If you do not want transparency, use the TIFF format.
Microsoft recommends that you save your picture at printer resolution for the completed picture size. For example, assume that you have an 8.5-by-2-inch letterhead, and you want to print the letterhead at a size of 2 inches. If your printer supports 600 dpi and an LPI of 85, set the picture resolution to 150 ppi at 2 inches, for a size of 300 x 71 pixels.
For more information about the graphics file types that are described in this article, visit the following third-party Web sites:
http://www.sanstudio.com/tech/GraphicFileTypes.htmlMicrosoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.
Article ID: 320314 - Last Review: May 7, 2007 - Revision: 3.6
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