@Jon & Ute: Thanks for the detailed info on the raster/vector/anti-aliasing stuff. I’ve never studied how images are rendered, so that’s all pretty new to me.

EMF is a vector format. Because of that it is freely scalable and will result in best quality.

All other formats are pixel-based and lose quality, especially when enlarged.

PNG usually is the best format for presentations. It’s compression is lossless, it can have 16 millions of colors, and can have transparent areas.

JPG uses a lossy compression, thus lines or gradients may look “dirty” due to compression artifacts.

GIF can only use 256 colors, thus gradients lose quality.

BMP is uncompressed, thus has good quality, but tends to be large.

For every small bitmap image: A line cannot be less than one pixel wide. Office uses anti-aliasing to smooth lines, but they need additional pixels. Because of that text in very small font sizes will lose quality, especially in serifs and diagonal lines. Your choice of a sans-serif font (Calibri?) was good, a serif font like Times New Roman or Garamond would look worse.

When exporting images, make them larger than you need them (200 %), then scale them down before printing or displaying on-screen, so the hardware (printer or graphic card) has a bit more information to enhance display quality.

2. JPG will be the worst of the raster images, since its optimization was designed for photographic images. I would not expect much (or any) difference in image quality between PNG, GIF, and BMP. BMP would result in a larger exported file, and GIFs will degrade if there are more than a handful (16? 32? some small power of 2) of colors. Office 2007 may degrade the image through overzealous use of antialiasing,

3. WMF and EMF should look best, since they recreate the actual elements of the chart with drawing objects. Office 2007 messes up metafiles through some strange mappings of chart element to shape type. Axis lines, for example, are represented by rectangles. Gridlines are represented by rectangles with uneditable lines across them.

4. Why not use actual charts?