Vector files are the most optimal file types for large-scale printing. Raster images can also work if they are 300dpi at 18" x 24".
Raster images are made up of a bunch of tiny pixels, while vector images are made from mathematical paths and can be infinitely scaled.
• You can upgrade any image to a vector graphic with Redraw.
• You can increase the resolution of a raster image with Upscale.
Vector file types: eps, ai, pdf, SVG, sketch
Raster file types: png, jpg, gif, tif, psd