Using the ODS GRAPHICS Statement

The output size of a graph is determined by the following:

When modifying the size of your graph, it is important to take into consideration the image scaling and aspect ratio, as well as the width and height of the graph. For example, rendering a graph to the LISTING destination at the default design size and default DPI of 100, produces a graph that is 640 by 480 pixels. If the same graph is rendered to the RTF destination, which has a default DPI of 200, the graph size is closer to 1280 by 960 pixels. The graph is scaled using 96 DPI as a baseline (640 * 200 / 96). In both cases, when this image is embedded into an RTF document, its size in the document is 6.4 in. by 4.8 in, since DPI data is included in the image. The aspect ratio of the graph is retained.

When the DPI of a graph is changed due to a change in output destination or user specification, the graph is scaled using a baseline DPI of 96 pixels. All graphical elements such as marker size, line thickness, font sizes, and gutters are also scaled linearly.

You can control the output size of a graph by specifying the WIDTH= or HEIGHT= options in the ODS GRAPHICS statement. In the ODS GRAPHICS statement below, taken from Controlling Graphics with the ODS GRAPHICS Statement, the WIDTH= option changes the width of the graph to 3.25 inches:

ods graphics on / 
      width=3.25in
      outputfmt=gif
      imagemap=on
      imagename="MyBoxplot"
      border=off;

Although you can use the ODS GRAPHICS statement to specify both the width and height, it is highly recommended that only one of these options be specified at a time. Using one option at a time ensures that the design aspect ratio of the graph is maintained.

When only width is specified, SAS uses the design aspect ratio of the graph to compute the appropriate height. Retaining the design aspect ratio of the graph is important in many cases as the graph might have a specific layout. For example, a plot that has multiple columns, or that has a statistics table on the side needs a wide aspect ratio. Changing the aspect ratio for this plot by specifying both width and height might produce unpredictable results.

When you use the WIDTH= option in the ODS GRAPHICS statement, the output size of the graph is computed based on the new size and the active DPI, using a baseline DPI of 96. All graphical elements such as marker size, line thickness, font size, and gutters are scaled using a non-linear scale. This is done to prevent rapid shrinking or growth of the fonts and markers.

Scaling of graph elements for change in graph size can be disabled by the ODS GRAPHICS statement options NOSCALE or SCALE=OFF. By default, scaling is on. Specifying NOSCALE or SCALE=OFF prevents the scaling of the graph elements. If you want to shrink your graph and keep the default sizes for fonts, use the NOSCALE or SCALE=OFF option in the ODS GRAPHICS statement.

It is often useful to produce a graph that fits in one column of a two column page. In this case, the column size might be 3.25 inches wide. You can place a default output image, which is 640 by 480 pixels, in this space, but then all graphical elements scale down. This results in small markers and unreadable small fonts.

In this case, it is useful to render the graph to the exact size required, and specify the correct DPI. In the situation above, you would specify a width of 3.25 inches and use the IMAGE_DPI= destination statement option to specify a DPI of 200. Then, the graph produced can be placed in the 3.25" wide column and the fonts and markers are readable.