A vision system for a vehicle includes a camera disposed at the vehicle and having a field of view exterior of the vehicle. The camera captures image data. A control includes an image processor operable to process image data captured by the camera. The control, responsive at least in part to putative detection of a traffic sign via image processing by the image processor of image data captured by the camera, enhances resolution of captured image data based at least in part on known traffic sign images to generate upscaled image data. The control compares captured image data to upscaled image data to determine and/or classify and/or identify the putatively detected traffic sign.