Bulk Image Resizing Software

I've found quite a few programs that will resize images in bulk, but none of them will quite do what I'm looking for.

I need to convert a number of images with various sizes (175x25, 140x100, 110x50, etc.) into 250x250. However, I don't want to stretch the original image, just add white trim around the outside of the image to make it 250x250. Any software I've found will only stretch the image. I can't do each image individually, because I have over 30,000 of them to go through. Does anyone know software that would do that in bulk?

 

How about this Microsoft power toy?
http://download.microsoft.com/download/whistler/Install/2/WXP/EN-US/ImageResizerPowertoySetup.exe

Just select the images you want then right click resize.

 

Thanks, but that's the same as all of the other software I've been using - it will either stretch the image, or size it so that its longest measurement is 250 pixels, but it won't add extra "white trim" so that the image is 250x250 without stretching.

 

Xn View will do that. Open the folder with your pics from this app, then click Edit>Select All. Then right click on your first image, choose Batch Convert, click the Transformations tab, pick Re-Size Canvas>Add. Then click on Re-Size Canvas where it just appeared in the new box. Input what you want, then click go.
http://www.majorgeeks.com/XnView__d4974.html

 

Click on the black color box and a new window will appear to choose any color.

 

Thanks musksnipe, that's exactly what I needed.

 

No prob.