| 摘要 |
A system and method is provided for selectively controlling the illumination, and particularly dark field illumination, applied to a symbol to be decoded, and for determining a suitable or optimized level of lighting for decoding the symbol. A ring-shaped illuminator is provided, and is segmented into a plurality of individually-controllable lighting portions which can be, for example, quadrants. Initially, illumination is provided to the symbol through an initial set of lighting conditions. Feedback from acquired image data is then used to determine whether the lighting is suitable for decoding the symbol and, if not, a controller varies the lighting applied to the symbol, and additional image data is acquired. This process is continued until suitable conditions are met. Alternatively, activation and deactivation of the lighting segments can be manually selected by an operator to provide suitable conditions.
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