MacPPT: Transparency Color Setting for Images Returns Unexpected Results (272781)

SYMPTOMS

When you insert pictures of various graphic types into a Microsoft PowerPoint 98 or PowerPoint 2001 presentation, and you set the background of the picture to be transparent so that the slide background color shows through, the results are not always consistent, depending on the color of the picture's background and graphic format. Unexpected symptoms may include one or more of the following:

Picture background colors that do not become transparent.
Colors within the picture's object, which are similar to the picture's background, that also become transparent.
A faint white border around the object approximately one or two pixels deep.
Streaks of the picture's background color that ought to be transparent. This last issue is most readily observed when a darker color is selected for the background color of the slides in the PowerPoint presentation.

WORKAROUND

To work around this issue, use either of the following methods.

Method 1: Use Portable Network Graphics Format

Use pictures in Portable Network Graphics (PNG) format instead of JPEG or TIFF format. In the graphics program that you use to create or edit pictures, open the picture that you want to use and save it in PNG format.

Method 2: Change the Image Background

If you do not want to change the image format, follow these steps.

NOTE: These steps assume that the background color of the image is white or some other light color.

Edit the image in the image editing software of your choice: Adobe Photoshop, Corel PhotoPaint, Graphic Converter, or others.
Choose a dark color for the image's new background, and make sure that the color is not one of the colors already in use in the image. If possible, choose a color that is a close match to the presentation's background.
If the fill tool in your image editor has a tolerance or anti-aliasing setting, test it to see what provides the best fill, with only a pixel or two overlap of the image. Most fill tools work best at about 25 to 30 percent of tolerance or anti-aliasing.
After you have calibrated the fill tool for your image, fill the white areas of the image with the dark color. If necessary, raise the color depth to at least 16-bit or to True Color.
Save a copy of your image; never overwrite the original image.
Insert the image into your presentation; then, use the transparency tool to set the new background color to transparent.