Use the dd command (Data Dump) – the most direct method.
sudo dd if=/dev/cdrom of=disc_image.iso bs=2048 Warning: dd is powerful. Make sure if= (input file) is your disc drive, not your hard drive. Not all ISOs are equal. A standard data ISO won't start your computer. To create a bootable OS installer, you need to preserve the "El Torito" boot catalog. iso file create
Tools like (for USB) or AnyBurn allow you to specify a "Boot Image." When creating the ISO from a folder (like a Windows DVD extraction), you must tell the software: "Sector 7 contains the boot loader." Use the dd command (Data Dump) – the most direct method