| 摘要 |
An imaging system (10) for producing image-representative signals representing information-bearing objects (30) includes a line imager (12) and an arrangement (32) for scanning (34) the object (30) so that image-representative signals are generated. A correction-signal generating arrangement (22) is used in a normalization mode (300) in which, with a white calibration object, each pixel (p1, p2, . . . , p2N) is averaged (A) over the width or length of the object (30). A correction factor is obtained by comparing the averaged value of the pixel over the white object with an ideal value. The correction factor (a) may be multiplicative, in which case it is the factor required to bring the average value to the ideal value, or (b) it may be additive, in which case it is the difference between the average value for that pixel and the ideal value. After the normalization or calibration, the processor (or firm- or hardware) processes each pixel of the information-bearing scans by applying the correction factor to produce corrected image-representative signals. The corrected signals may be used by conventional information-extraction techniques, such as optical character recognition.
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