When you choose our cropping option, we remove this black area giving you the maximum image area possible.
Slides with rounded corners come with another challenge. They result in small black triangles in each of the corners of the scanned images. If we were to crop the images to get rid of these triangles, you would loose a small portion of the image. While this won't make much difference in most images, in some it could mean you are cutting off someone's head.
To prevent this we have come up with a creative solution. In Photoshop, we select each of these triangles and use a feature called "Content Aware Fill" to sample image data from around the area to be filled, then reconstruct the area based on the sampled data.
When you select this option we do this step for you saving you time and money.