pic_1.ppm       pic_001.ppm
pic_10.ppm      pic_010.ppm
scan_1.ppm      scan_0001.ppm
scan_9.ppm      scan_0009.ppm
scan_10.ppm     scan_0010.ppm
scan_99.ppm     scan_0099.ppm
scan_100.ppm    scan_0100.ppm
scan_999.ppm    scan_0999.ppm