1. A signal processing system comprising: an original image acquiring module for acquiring an image signal of an original image; a signal enhancement module for enhancing the image signal of the original image, so as to obtain an image signal of a final image having a pixel resolution no less than that of the original image, wherein the original image acquiring module includes a plurality of image receiving ports, and the plurality of image receiving ports are respectively configured for acquiring an original image with different pixel resolutions; the signal enhancement module comprises: a first signal converting unit for converting an image signal of the original image from an RGB signal into an intermediate YUV signal; a signal enhancement unit for performing an edge enhancement on a Y signal of the intermediate YUV signal, and adjusting any one of color levels, black and white levels, and hues of a U signal and a V signal of the intermediate YUV signal respectively, so as to obtain an enhanced intermediate YUV signal; and a second signal converting unit for converting the enhanced intermediate YUV signal into an intermediate RGB signal, so that the final image is displayed based on the intermediate RGB signal; wherein the first signal converting unit comprises: a signal converting subunit for converting the image signal of the original image from the RGB signal into a YUV signal of the original image; and a signal scaling-up subunit for scaling-up the YUV signal of the original image, so as to obtain the intermediate YUV signal.