Humans cannot directly "read" or interpret standard universal product code (UPC) or data matrix barcodes in the sense of translating the visual series of parallel black-and-white lines or data squares into raw alphanumeric characters. However, human eyes can easily read the human-readable text strings printed directly beneath or beside the barcode lines, which display the exact corresponding numbers. Decoding the actual barcode symbology itself requires optical scanners, laser readers, or digital image-processing algorithms designed to measure the precise widths of bars and spaces.