Batch Padding Images to Specific Size with White Background

[rohit92]

So I have bunch of images that I want to pad the images to 500 x 500 px. All the images vary in size and I know that automator has an action for padding images to a black background. But there is no action to pad images with a white background. Any body have an idea on how to do this? I have been spending about an hour to figure out a way to do this by batch processing and have not been able to find anything. Even if there is a separate app to do this, let me know. The easiest thing would be for there to be a way to just adjust the color in automator though.