Maybe a little clarification is needed because vector graphics are drawings, so converting a photo to vector means making a drawing of the photo and that isn't necessarily what is needed or wanted.
If the images you want printed in large format are:
A. PhotosImages that are captured with a camera need to be supplied in high resolution (large image*) format. Photos are not scalable so simply enlarging a small image will result in a poor quality large image. The photo must have been taken with a high quality setting on the camera, at the size needed for the project, or larger. Your printer should be able to tell you the pixel dimension (photo size) needed for the specific project. Photo to vector conversion is recommended only if you want a drawing made, based on the photograph.
B. GraphicsDrawings such as logos and illustrations may be supplied to your printer in high resolution OR vector format. The good thing is that if you don't have a high resolution image, most graphics can simply be converted (redrawn) in scalable vector format and will be suitable to be printed at any size.
If your image has both, the graphics may be supplied to your printer in high resolution or vector format, the photo will need to be supplied as a high resolution image.
When is photo to vector conversion recommended?Photo to vector conversion is ideal for projects where photos cannot be used, such as engraving, embroidery, vinyl-cut signs, or whenever you prefer a drawing instead of a photo. For vector re-drawing quote and samples, please visit vector-conversions.com
*Large dimensions: the pixel width and height of the image, not the kb file size.
Please feel free to ask questions or make suggestions via the comments below.