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## Image annotation objects

Image annotation objects, shown in figure, are created by clicking the Image button in the Create new area on the Objects tab. Image annotation objects display images from image files on disk in a visualization window. Images are drawn on top of plots in the visualization window and are useful for adding logos, pictures of experimental data, or other views of the same visualization. Image annotation objects can be placed anywhere in the visualization window and you can set their size, and optional transparency color.

The first step in incorporating an image annotation into a visualization is to choose the file that contains the image that will serve as the annotation. To choose an image file for the image annotation, type in the full path and filename to the file that you want to use into the Image source text field. You can also use the file browser to locate the image file if you click on the "..." button to the right of the Image source text field in the Image annotation interface, shown in figure. Note that since image annotations are incorporated into a visualization inside of VisIt's viewer component, the image file must be located on the same computer that runs the viewer.

Figure 20

After selecting an image file, you can position its lower left coordinate in the visualization window. The lower left corner of the visualization window is the origin (0,0) and the upper right corner of the visualization window is (1,1).

Once you position the image where you want it, you can optionally scale it relative to its original size. Unlike some other annotation objects, the image annotation does not scale automatically when the visualization window changes size. The image annotation will remain the same size - something to take into account when setting up movies that use the image annotation. To scale the image relative to its original size, enter new percentages into the Width and Height spin boxes or click their +/- buttons. If you want to scale one dimension of the image and let the other dimension remain unchanged, turn off the Lock aspect check box.

Finally, if you are overlaying an image annotation whose image contains a constant background color or other area that you want to remove, you can pick a color that VisIt will make transparent. For example, figure shows an image of some Curve plots overlayed on top of the plots in the visualization window and the original background color in the annotation object was removed to make it transparent. If you want to make a color in an image transparent before VisIt displays it as an image annotation object, click on the Transparent color check box and then select a new color by clicking on the Transparent color button and picking a new color from the Popup color menu.