Auto cropping of scanned images works best on scanners that have a black background such as the DocketPort 465 or DSMobile 600 and other sheet feed scanners. For flatbed scanners, you should use the cropping mechanisms built in as they will be more accurate (your eye is sometimes better than a computer). In addition, you can try using grayscale or color for the scanner setting. While black and white makes detection of the images easy, any random noise in the scan will throw off the detection.