Charge coupled device based blemish detection system and method
First Claim
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1. A system for detecting blemishes on an illuminated object comprising:
- a digital storage device;
a charge coupled device (CCD);
output circuitry for transferring data from said CCD to said digital storage device, whereby the data from each pixel of said CCD is stored at a specific address within said digital storage device;
means for averaging the signals from the adjacent pixels surrounding a particular pixel and providing an average signal;
address generator means for providing the address of the square area containing said adjacent pixels to said digital storage device to transfer the signals from said adjacent pixels to said means for averaging;
means for receiving the particular signal from said particular pixel;
means for receiving said average signal and said particular signal and providing a difference signal representative of the difference between said average signal and said particular signal;
means for providing a threshold signal representative of the permissible maximum of said difference signal; and
comparator means for receiving said difference signal and said threshold signal and providing a blemish signal when said difference signal exceeds said threshold signal.
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Abstract
A system for detecting blemishes on an illuminted object, such as the screen of a kinescope, includes a charge coupled device (CCD). The signal from each CCD pixel is compared with the average of the signals of all pixels immediately adjacent to the pixel being investigated to provide a difference signal. The difference signal is compared to a threshold level and a blemish signal generated when the difference signal exceeds the threshold.
30 Citations
7 Claims
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1. A system for detecting blemishes on an illuminated object comprising:
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a digital storage device; a charge coupled device (CCD); output circuitry for transferring data from said CCD to said digital storage device, whereby the data from each pixel of said CCD is stored at a specific address within said digital storage device; means for averaging the signals from the adjacent pixels surrounding a particular pixel and providing an average signal; address generator means for providing the address of the square area containing said adjacent pixels to said digital storage device to transfer the signals from said adjacent pixels to said means for averaging; means for receiving the particular signal from said particular pixel; means for receiving said average signal and said particular signal and providing a difference signal representative of the difference between said average signal and said particular signal; means for providing a threshold signal representative of the permissible maximum of said difference signal; and comparator means for receiving said difference signal and said threshold signal and providing a blemish signal when said difference signal exceeds said threshold signal. - View Dependent Claims (2, 3, 4)
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5. A method for detecting blemishes on an illuminated object comprising the steps of:
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generating an illuminated field on the screen of said object; imaging said field with a CCD and transferring the CCD data to a digital storage device wherein the data from each pixel of said CCD is stored at a different address; averaging the data from the immediately adjacent pixels surrounding a particular pixel to obtain an average signal; taking the difference between the data from said particular pixel and said average signal to obtain a difference signal; comparing said difference signal to a threshold signal and providing a blemish signal when said difference signal exceeds said threshold; and providing said blemish signal to a memory to store the address of said particular pixel whereby the location of the blemish which caused said blemish signal is known. - View Dependent Claims (6, 7)
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Specification