Add a picture watermark to all slides

PowerPoint doesn't currently support watermarks, but here's a workaround: 

1. Go to View > Slide Master and select the first slide in the navigation pane.

2. Select Background Styles > Format Background, and then choose Picture or texture fill.

3. Go to Picture Source > Insert.

4. Choose the location of your picture, find the image you want to use as a watermark, and select Insert.

To create a text watermark, see Create a text watermark.

PowerPoint doesn't currently support watermarks, but here's a workaround: 

1. On the View tab, click Slide Master and select the slide master at the top of the thumbnail pane.

2. Select Background Styles > Format Background, and then choose Picture or texture fill.

3. Under Picture source, select Insert. Locate and select the picture you want, and then select Insert.

4. In the Format Background pane, slide the Transparency bar to the right to set the opacity percentage.

PowerPoint doesn't currently support watermarks, but here's a workaround. Keep in mind that you can't adjust an image's transparency in PowerPoint for the web. So you may need to add transparency to your photo in an image editor before applying it to your slides. 

1. Select the Design tab.

2. Select Background > Insert Picture, then choose This Device or Stock Images.

3. Choose a picture file, then select Open or Insert.

4. To apply this background image to all slides, select Background > Apply to All.