Method for shading an optical sensing element such as in a scanner

A method for shading an optical sensing element of a scan bar of an optical scanner having a shading calibration strip comprising the steps of:

• a) seciuentially obtaining reference values of the output signal of the optical sensing element while relatively moving the scan bar including the optical sensing element over the shading calibration strip;
• b) applying an edge detection filter to each of the reference values obtained in step a) in determining if each of the reference values is or is not from an optical defect on the shading calibration strip;
• c) calculating an average of the reference values obtained in step a) while excluding each of the reference values determined to be from an optical defect in step b) in calculating the average;
• and
• d) calibrating the output signal of the optical sensing element to the shading calibration strip using at least the average calculated in step c);
• and also including the step of determining if the first reference value determined by step b) to be from an optical defect is actually of a trailing edge of an optical defect and including the step of restarting steps b) and c) at a reference value at or past the trailing edge of the optical defect.

A method for shading an optical sensing element of an optical sensor comprising the steps of:

• a) sequentially obtaining reference values of the output signal of the optical sensing element while relatively moving the optical sensor including the optical sensing element over a shading reference target;
• b) applying an edge detection filter to each of the reference values obtained in step a) in determining if each of the reference values is or is not from an optical defect on the shading reference target;
• c) calculating an average of the reference values obtained in step a) while excluding each of the reference values determined to be from an optical defect in step b) in calculating the average;
• and
• d) calibrating the output signal of the optical sensing element to the shading reference target using at least the average calculated in step c).

A method for shading an optical sensing element of an optical sensor comprising the steps of:

• a) sequentially obtaining reference values of the output signal of the optical sensing element while relatively moving the optical sensor including the optical sensing element over a shading reference target;
• b) applying an edge detection filter to each of the reference values obtained in step a) in determining if each of the reference values is or is not from an optical defect on the shading reference target;
• c) calculating an average of the reference values obtained in step a) while excluding each of the reference values determined to be from an optical defect in step b) in calculating the average;
• and
• d) calibrating the output signal of the optical sensing element to the shading reference target using at least the average calculated in step c);
• and also including the step of determining if the first reference value determined by step b) to be from an optical defect is actually of a trailing edge of an optical defect and including the step of restarting steps b) and c) at a reference value at or past the trailing edge of the previous optical defect.