What is Decodability?
Although a fairly easy concept in principle, Decodability is harder to explain in a few words. It measures how close the dimensions within the symbol are to their ideal values, and as such is a measure of its dimensional accuracy. However, it only applies to those measurements needed by the decode algorithm to determine the width of an element, or the combined widths of elements, in order to decode the symbol character. Taking a simple case, if it is a question of determining a particular width, the decode algorithm might say something like “If the measurement is between 2.5 modules and 3.5 modules, treat it as equal to three modules.” In other words, 2.5 modules is the threshold value between two modules and three modules, and 3.5 modules is the upper threshold between three and four modules; there is a 0.5 module margin on either side of the nominal measurement of 3.0. Decodability measures how much of this margin is left in the worst (most deviating) measurement: assume the measurem
