Many people ask me, "How did you get your slide background images to smoothly become transparent like that?" Well, in Powerpoint, an image's transparency can be controlled, but you have to choose the degree of transparency and apply it to the whole image. To make a background image like the one below, you will need to use Adobe Photoshop, or some other photo editing software that allows you to apply a gradient mask across an image. If you use Apple's Keynote presentation software you can apply PNG images to your slides. PNG images contain an invisible mask that allows you to use photos that can have a transparency ranging from 0%-100%.

The final slide in Keynote using a PNG image. PNG images are a bit different than JPEGs because they allow you to use an Alpha Channel in the image file. It is the Alpha Channel which makes the smooth transparency gradient possible.
(1) The original blank slide.

 (2) The slide with the text added.
(3) This is the picture I wanted to use...

 (4) The picture is good, but does not provide a good contrast with the text. The photo also has an abrupt edge, and the subject is looking away from the bullet points.
(5) This composite photo was blended with the original photo (using "overlay" in Photoshop layers) to give it a nice touch of a rich blue tint. Shades of blue generally make good background colors as they recede to the back allowing the white text to appear to come forward. .


(6) Here you can see the image after the layers have been blended. Then the eraser tool was used to carefully create a smooth transition from 100% transparency on the left edge to about 5% transparancy on the right.
(7) Left: Instead of using the eraser tool, you can simply use "Channels" in Photoshop and create a mask. Using the gradient tool it is possible to make a smooth transition. The white part of the mask represents the levels of transparancy (i.e., the part of the image that was deleted or "erased").
Below is an example of using Photoshop to create an Alpha Channel and delete all of the background color. In Powerpoint you can actually do this with the photo editing tool ("Set Transparent Color"), but the results may not be as smooth as you like. If you use Apple's Keynote, you can use PNG images (which allows Alpha Channels) in your slides like the image below.
The original JPEG image with
a white background.
 Using the "Magic Wand Tool" in Photoshop, it was easy to remove the background color (with some fine tuning). The white & grey checkered background tells us that the areas around the subject are "invisible."
Here is the PNG image being placed into the Keynote slide.

 Notice the nice drop shadow above the subject. This is something available in Keynote only. You could make a slide exactly like the one above in Powerpoint, but you would have to do more work in Photoshop first.