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C.3.2 GMT graphics in PowerPoint

Figure: Examples of rendered images in a PowerPoint presentation.

Figure: PowerPoint's ``Format Picture'' dialogue to set scale and rotation.

In Figure C.1 we have attempted to include Figure 7.20 into a PowerPoint presentation. First the PostScript file was converted to PDF (using ps2raster), then loaded into PowerPoint and the white background color was made transparent using the formatting toolbar (shown on the left side of Figure C.1). Clearly, when we let PowerPoint do the rendering, we do not get the best result:

1. The anti-aliasing causes the tiles that make up the land to stand out. This is because the anti-aliasing algorithm blurs all edges, even when the tiles join seamlessly.
2. The background color was assumed to be white, hence the text is ``smoothed'' using gray shades. Instead, shades of blue which would be appropriate for the background we are using.

On the central column of Figure C.1 we have included PNG versions of a portion of the same example. This shows the workings of anti-aliasing and different resolutions. All samples were obtained with convert. The one on the top uses all default settings, resulting in an anti-aliased image at 72 dpi resolution (very much like the PDF included directly into PowerPoint).

Just switching anti-aliasing off (middle) is clearly not an option either. It is true that we got rid of the gray blurring and the seams between the tiles, but without anti-aliasing the image becomes very blocky. The solution is to render the image at a higher resolution (e.g., 300 dpi) without anti-aliasing and then shrink the image to the appropriate size (bottom of the central column in Figure C.1). The scaling, rotation as well as the selection of the transparent color can be accomplished through the ``Formatting'' tool bar and the ``Format Picture'' dialogue box of PowerPoint (Figure C.2), which can be found by double clicking the included image (or selecting and right-clicking or control-clicking on a one-button mouse).

Next: C.4 Concluding remarks Up: C.3 Examples Previous: C.3.1 GMT graphics in Contents Index