摘要 |
The invention provides an apparatus for pre-processing sensor data that represent measurements of a physical parameter of a material under inspection. Sensors are employed to provide a multiplicity of data associated with a corresponding multiplicity of small areas of the material; and a multiplicity of reference data are also generated, each reference datum being associated with a particular sensor datum. From the sensor data and the reference data there are derived a multiplicity of output signals to be delivered to a signal processor, each output signal being dependent on at least two reference data and an associated sensor datum. |