Creating Perfect White Borders

We are an art publisher. Our product is an art print – a printed picture on a piece of paper. Many of our pieces of paper have the image in the middle, and white paper surrounding that image (the border). We give out digital files of our images to many web retailers. Some want the images without the white border shown, and some do. We have on hand all our images (12,000 of them) without any white border shown (we call that full bleed). We have in a data table the dimensions of the image (for each product), the dimensions of the paper, and the size of the left border and the top border. We can mathematically generate the size of the right border and the bottom border. We can generate percentages or proportions as well. All this data can be made available in any format: txt, csv, xls, dbaseIII, whatever. We need an automated way to add the exact right amount of white all around the image, on each of the 11,000 scans we have on file. Here is the process if we were to do it by hand: 1. Get all the measurements of the real product. (ex: 10x10 with 1” borders all around=10% border) 2. Get the scan, and measure it (in pixels) (ex. 400x400 pixels) 3. Calculate the size of a white field, which, when placed behind the image scan, will be just the right size. (ex.: 480x480) 4. Layer the image over the white field, place it precisely in the right position. 5. Flatten the image. 6. Save the image. 7. Do the remaining 10,999 images. In practice, we need a program that we can point at a data file, tell it where to find its images, and where to place the finished images, then let it run. Ideally it would run on a Mac or PC, but a Mac is our bias. The program could run as a standalone, or be a PhotoShop plug in. We have and use Photoshop all the time.