The "Set Transparent Color" tool leaves a ragged border around foreground image in PowerPoint

When you insert a picture into a Microsoft PowerPoint presentation, and you use the Set Transparent Color tool to make the background of the picture transparent, a thin, ragged border may appear around the foreground image in your picture, as if the color of the foreground image is bleeding into the background slightly.

This behavior occurs because the edge of the foreground image contains pixels that are not quite the same color as the image's background color (now transparent) and the non-transparent color portion of the graphic; this slight color variation is the result of an anti-aliasing or smoothing process.

Because the Set Transparent Color tool can treat only one color as transparent, these edge (or border) pixels, which appear to be the same color as the background, are not set to transparent.

This behavior can also occur if the background color is not really one color, but a mixture of two or more colors.

To work around this issue, use a graphic program like Microsoft PhotoDraw to save the image in a format that is specifically for use in a Microsoft PowerPoint presentation. PhotoDraw uses the Portable Network Graphics (PNG) format, but other such programs may have different options to permit you to set the transparency properties when you create or edit the image.

However, if you are using a Windows Bitmap image, you must set the transparency of the background manually before you save the image in a format suitable for use in a PowerPoint presentation.

If you are using other image editing software, please consult that product's manual and help files for directions about how to make a color transparent.

To use PhotoDraw to save an image for use in a PowerPoint presentation, follow these steps:

1. Start PhotoDraw and open the image that you want to use in your PowerPoint presentation.
2. On the File menu, click Save for Use In.
3. In the first step of the wizard, click In a Microsoft PowerPoint or similar slide presentation, and then click Save.
4. In the Save As dialog box, name your image, and then click Save.

Your image is now saved in PNG format, ready for use in your PowerPoint presentation. The background of the PNG image and any portions that you have manually set as transparent (the canvas area in PhotoDraw where no pictures cover the canvas) will be transparent in the picture when it is inserted into PowerPoint.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.