Efficient method for reading meter values by processing digital images of a meter

A method for reading a meter, comprising:

• capturing an image of digits displayed by the meter;
• roughly locating the digits in the image by correlating the entire image against symbols from a symbol mask set;
• after said roughly locating, precisely locating the digits by correlating the digits against the symbols that are rotated, resized, and repositioned to maximize correlation between the symbols and the digits;
• determining nominal center positions of the digits;
• storing the nominal center positions of the digits in a nonvolatile memory;
• capturing another image of the digits displayed by the meter;
• locating a region of interest according to one of the nominal center positions of the digits;
• for a fully visible digit in the region of interest;
• determining a vertical position of the digit;
• retrieving a symbol from the symbol mask set;
• aligning the symbol and the digit according to the vertical position of the digit;
• and
• correlating the symbol and the digit;
• and
• for two partially visible digits in the region of interest;
• determining an antipodal vertical position of the two digits;
• retrieving an intermediate portion between adjacent symbols from the symbol mask set;
• aligning the intermediate portion and the two partially visible digits according to the antipodal vertical position of the two partially visible digits;
• and
• correlating the intermediate portion and the two partially visible digits.