1. Look at your file format
  2. If your format file is .eps or .ai, please launch Adobe Illustrator
  3. Windows > Link > if your graphics are in the Link section, that means, it is an image
  4. Select All > if you see all the dots around the graphic, it is in vector format
  5. Another simple way to check actually is to zoom 2000%, and if your graphic is in solid lines, that means your artwork is in vector format, but if your artwork is blur and has patchy area around it, that means that your artwork is an image