How are graphic properties set for exporting, printing, or viewing maps?

Answer

This article explains how ArcMap sets the graphic properties of maps when they are viewed on a screen, printed, or exported to PDF or JPEG format.

Microsoft's Graphics Device Interface (GDI) is used for drawing to screen, to printer, and to map exports. GDI, in turn, obtains graphic properties from a device context, which can also be considered a drawing environment. Each device context has a resolution, along with other properties (such as color bit depth) that can determine how GDI drawing calls are rendered to the device.

When drawing to the screen, ArcMap uses the drawing context of the screen. This ensures that the resolution for drawing and the bit depth of colors will match the screen's effective resolution and bit depth – usually 96, 120, or 144 DPI (dots per inch), and 32 bits.

For printing, ArcMap obtains this information from the printer selected in ArcMap's Page Setup (File > Page and Print Setup). This ensures that drawing to the printer context is suitable for the printer's driver.

When exporting to a graphical interchange format, such as PDF or JPEG, ArcMap uses information from Windows' default printer. This may not be the same printer selected in the ArcMap Page Setup. Discover which printer this is by viewing printers in Windows' Control Panel. The default printer has a check mark icon over it.

Exports use the default printer's hardware context; therefore the default printer affects the accuracy and appearance of exports. Rendering of text and other font-based symbols can be affected, as well as the placement of vector features.

In general, using a default printer that is a high-resolution, large-format plotter gives the best results. If no such printer is available, the driver for a printer that meets these requirements can be installed as a test printer by downloading and installing the printer driver from the manufacturer's Web site.

By selecting a default printer with a resolution that is at or above the resolution of the requested export, rounding errors that affect placement of vector features can be minimized, and the accuracy of rasterization of features whose symbology requires rasterization (such as transparent layers or layers with rasterizing symbology) can be improved.

The articles below go over the procedure to install a test printer, as well as some common issues resulting from the device context of the default printer.

Note:
It is highly recommended to use ArcGIS Pro for printing and exporting, especially when experiencing issues caused by the limitations of the ArcMap display engine. More specifically, ArcGIS Pro is not restricted by the graphical device interface (GDI) limitations that some users experience in ArcMap. For example, transparency is natively supported in ArcGIS Pro, preventing the rasterization of layers. Additionally, ArcGIS Pro supports transparency in layout elements. See: Migrate from ArcMap to ArcGIS Pro for more information.

Note:
ArcGIS Pro does not support exporting directly to AI (Adobe Illustrator) files as it is a closed file format.  
It is recommended to export to the AIX format and use the ArcGIS Maps For Adobe Creative Cloud extension in Adobe Illustrator to open the exported AIX files.  
For more information on the subtle differences between ArcMap and ArcGIS Pro in drawing, please see the help topic: Visual differences in imported map documents