Local tone mapping for symbol reading

An apparatus for reading a barcode symbol, the apparatus comprising a processor in communication with memory, the processor being configured to execute instructions stored in the memory that cause the processor to:

• acquire a raw image of a barcode symbol, where each pixel of the raw image has a digital value having a raw bit depth;
• identify a region-of-interest of the raw image;
• determine a local pixel neighborhood metric for at least one raw pixel in the region-of-interest based on an attribute of a symbology of the barcode in the raw image, wherein the local pixel neighborhood metric identifies on one or more raw pixels near the at least one raw pixel;
• determine a local mapping function for the at least one raw pixel that maps the value of the raw pixel to a mapped pixel value with a mapped bit depth that is smaller than the bit depth associated with the raw image, wherein the local mapping function is based on:
• a value of a set of raw pixels near the at least one raw pixel within the local pixel neighborhood metric;
• and
• at least one parameter determined based on the raw image;
• compute a mapped image for the region-of-interest, comprising determining a pixel value for at least one mapped pixel value in the mapped image by applying the local mapping function to the raw pixel value in the raw image to generate the mapped pixel value;
• and
• decode the barcode symbol using the mapped image.

At least one non-transitory computer-readable storage medium storing processor-executable instructions that, when executed by at least one computer hardware processor, cause the at least one computer hardware processor to perform the acts of:

• acquiring a raw image of a barcode symbol, where each pixel of the raw image has a digital value having a raw bit depth;
• identifying a region-of-interest of the raw image;
• determining a local pixel neighborhood metric for at least one raw pixel in the region-of-interest based on an attribute of a symbology of the barcode in the raw image, wherein the local pixel neighborhood metric identifies on one or more raw pixels near the at least one raw pixel;
• determining a local mapping function for the at least one raw pixel that maps the value of the raw pixel to a mapped pixel value with a mapped bit depth that is smaller than the bit depth associated with the raw image, wherein the local mapping function is based on:
• a value of a set of raw pixels near the at least one raw pixel within the local pixel neighborhood metric;
• and
• at least one parameter determined based on the raw image;
• computing a mapped image for the region-of-interest, comprising determining a pixel value for at least one mapped pixel value in the mapped image by applying the local mapping function to the raw pixel value in the raw image to generate the mapped pixel value;
• and
• decoding the barcode symbol using the mapped image.