Change background color of slideshow with no popup

[tiabradford]

Hello,

I have a gallery with hundreds of images, most of which have the same dimensions. I have set the size of the detail window to be the dimensions of 8.5X11 (the size of most of the images). I do however have some images that are slightly smaller. I am using the Detail Window option of No Popup. When the slideshow is played, if the images are smaller than 8.5X11 it leaves a black space around it so the image does not blend in with the white background of the overall website.

While it is possible to adjust the size of the images using Photoshop, this would take hours to do. I was wondering if there was a quick way to make the background show white in the gap areas instead of black?

Thanks

[Jan]

Hi which format the images have? Is this transparent PNG?