About Supported Formats for the Autodesk Raster Driver

Specifies the format and background color to use when outputting a drawing to a raster image file.

The Autodesk Raster driver is used to output the graphics of the objects in a drawing file to a raster image file. The raster image file that is created can then be viewed by those without access to an AutoCAD-based product, archived for historical purposes, or attached to another drawing without the need to have access to the original drawing file.

A drawing file can be output to one of the raster image file formats listed in the following table:

Format	Color Depth	Extension
MS-Windows BMP (Uncompressed DIB)	Bitonal, grayscale, indexed, RGB	.bmp
Truevision TGA Version 2 (Uncompressed)	Indexed, grayscale, RGB, RGBA	.tga
ZSoft PC Paintbrush PCX (ZSoft Packbits Compression)	Indexed, RGB	.pcx
TIFF Version 6 (Uncompressed)	Bitonal, indexed, grayscale, RGB, RGBA	.tif
TIFF Version 6 (CCITT G4 2D Compression)	Bitonal, indexed, grayscale, RGB, RGBA	.tif
CALS MIL-R-28002A Type 1 (CCITT G4 2D Compression)	Bitonal	.cal
Dimensional CALS Type 1 (CCITT G4 2D Compression)	Bitonal	.cal
Independent JPEG Group JFIF (JPEG Compression)	Gray, RGB	.jpg
Portable Network Graphics PNG (LZH Compression)	Bitonal, grayscale, indexed, RGB, RGBA	.png

Each raster image file format offers different advantages; some formats offer compression and smaller file sizes which makes them ideal for sending in emails or posting online, while others provide better visual fidelity and are ideal as references in a drawing file but are much larger in size. Unlike vector graphics, the visual fidelity of a raster image file varies based on the compression level, output size, and resolution chosen. The raster image file type you choose should match how it will be used.

The following are some of the more commonly used formats when output a drawing to a raster image file:

• BMP - BMP files are Microsoft Windows bitmap files; these files can be created in and read by Windows Paint along with many other Windows-based applications. BMP files are a good choice when you are not sure how the output file might be used; the are somewhat large in size but the graphics are not compressed which allows them to retain better visual fidelity when scaled or zoomed in.
• JPEG - JPEG (or JPG) files are more commonly associated with the digital photography industry and were developed by the Joint Photographic Experts Group. Unlike BMP files, JPEG files are typically smaller and more compressed. As a result of them being compressed, the quality can suffer when scaling or zooming in the image.
• TIFF - TIFF (tagged image file format) is a raster file format jointly defined by Adobe and Microsoft. TIFF files are typically much larger in size when compared to BMP and JPEG files, but they offer much higher resolutions which helps to retain the visual fidelity of the image when scaled or zoomed. Since TIFF files typically are higher resolution images, they are often used for mapping and satellite imagery that requires higher quality images.

Controlling the Output of the Autodesk Raster Driver

You can specify which raster image file format and other output settings when configuring a device that uses the Autodesk Raster driver.

The Source and Size node under Media in the Plotter Configuration Editor dialog box allows you to specify the output size of the image. All of the sizes represent an output with an aspect ratio of 1:1. Some of the file formats offer a choice of color or monochrome along with a choice of color depth (for example, 2 shades of gray, 256 colors, and so on) and resolution. Graphics settings can be specified by expanding Graphics in the Plotter Configuration Editor dialog box and selecting the Vector Graphics node. The previous table listed the supported raster image file formats and the available color depth options along with the file extension of the relevant output file. In the Color Depth column of the table, the indexed value represents the color depths of 8-bit, 256 colors, RGB is 24-bit True Color, and RGBA is 32-bit True Color.

The Custom Properties node in the Plotter Configuration Editor dialog box allows you to set the background color for the image and determine if the scanlines of the image should be rotated 90 degrees. Not all supported image formats allow the setting of a background color and rotation of the scanlines 90 degrees.