White reference data generating unit applied to shading correction system

A white reference data generating unit for generating white reference data based on image data which is obtained while an image sensor means is scanning on a white reference plate in a predetermined number of lines, said white reference data being used in a shading correction process, said white reference data generating unit comprising:

• storage means for storing the white reference data;
• determination means, coupled to said image sensor means, for determining whether or not the image data supplied from said image sensor means is equal to or less than a threshold level based on data stored as the white reference data in said storage means;
• updating means, coupled to said storage means and said image sensor means, for updating the white reference data stored in said storage means to new white reference data calculated based on the white reference data stored in said storage means and the image data supplied from said image sensor means while said image sensor means is scanning each line on said white reference plate;
• and
• inhibition means, coupled to said determination means and said updating means, for inhibiting said updating means from updating the white reference data stored in said storage means when said determination means determines that the image data supplied from said image sensor means is equal to or less than the threshold level.

A white reference data generating unit for generating white reference data based on image data which is obtained while an image sensor means is scanning on a white reference plate in a predetermined number of lines, said white reference data being used in a shading correction process, said white reference data generating unit comprising:

• storage means for storing white reference data obtained by scanning of the white reference plate;
• determination means, coupled to said image sensor means, for determining whether or not the image data supplied from said image sensor means is equal to or less than a threshold level based on data stored as the white reference data in said storage means;
• updating means, coupled to said storage means, for updating the white reference data stored in said storage means to new white reference data calculated based on the white reference data stored in said storage means and input data while said image sensor means is scanning each line on said white reference plate;
• and
• supply means, coupled to said storage means, said determination means and said updating means, for supplying the image data, as the input data, to said updating means when said determination means determines that the image data is greater than the threshold level, and for supplying difference data, as the input data, to said updating means when said determination means determines that the image data is equal to or less than the threshold level, said difference data being obtained by subtracting a first value from the white reference data stored in said storage means.

A white reference data generating unit for generating white reference data based on image data which is obtained while an image sensor means is scanning on a white reference plate in a predetermined number of lines, said white reference data being used in a shading correction process, said white reference data generating unit comprising:

• storage means for storing white reference data obtained by scanning of the white reference plate;
• determination means, coupled to said image sensor means, for determining whether or not the image data supplied from said image sensor means is equal to or less than a threshold level based on data stored as the white reference data in said storage means;
• updating means, coupled to said storage means and said image sensor means, for updating the white reference data stored in said storage means to new white reference data calculated based on the white reference data stored in said storage means and the image data supplied from said image sensor means while said image sensor means is scanning each line on said white reference plate;
• and
• inhibition means, coupled to said determination means and said updating means, for inhibiting said updating means from updating the white reference data stored in said storage means when said determination means determines that the image data supplied from said image sensor means is equal to or less than the threshold level.