Time variant defect correcting method and apparatus in infrared thermal imaging system

A time variant defect correcting method in an infrared thermal imaging system, comprising the steps of:

• receiving digital video signals representing a frame;
• calculating edge values of a first pixel in the frame with respect to at least two of pixels adjacent to the first pixel;
• counting the number of defect determinations made for the first pixel if the edge values exceed a threshold edge value;
• receiving digital video signals representing a next frame and calculating the edge values of a next pixel that has a position corresponding to the first pixel in the next frame with respect to at least two of pixels adjacent to the pixel, if the count value is equal to or less than a threshold count;
• and
• registering the first pixel as a defect and correcting the defect, if the count value exceeds the threshold count.

A time variant defect correcting method in an infrared thermal imaging system, comprising the steps of:

• receiving digital video signals representing a frame;
• calculating edge values of a first pixel in the frame with respect to at least two of pixels adjacent to the first pixel;
• calculating an average display level of the adjacent pixels if the edge values exceed a threshold edge value;
• calculating the difference between the calculated average display level and the average display level of the adjacent pixels in a previous frame;
• counting the number of defect determinations made for the first pixel if the difference exceeds a threshold average difference;
• receiving digital video signals representing a next frame and calculating the edge values of the first pixel in the next frame with respect to at least two of pixels adjacent the first pixel, if the count value is equal to or less than a threshold count;
• and
• registering the first pixel as a defect and correcting the defect, if the count value exceeds the threshold count.

A time variant defect correcting apparatus in an infrared thermal imaging system, comprising:

• a first memory for receiving digital video signals representing a frame at every frame period;
• an image processor for determining whether a first pixel from the frame is likely to be a defect, counting a number of defect determinations for the first pixel if the first pixel is likely to be a defect, comparing the count value with a threshold count, receiving digital video signals representing a next frame and determining whether a next pixel that has a position corresponding to the first pixel in the next frame is likely to be a defect, if the count value is equal to or less than the count threshold, and registering the first pixel as a defect and correcting the defect, if the count value exceeds the threshold count;
• and
• a second memory for storing the location of the first pixel registered as a defect.

A memory medium including code for correcting time variant defects, the code when executed causes an infrared thermal imaging system to perform steps comprising;

• (1) receiving digital video signals representing a frame;
• (2) determining whether a first pixel from the frame is likely to be a defect;
• (3) counting the number of defect determinations for the first pixel if the first pixel is likely to be a defect;
• (4) comparing the count value with a threshold count;
• (5) receiving digital video signals representing a next frame and determining whether a next pixel in a position corresponding to the first pixel in the next frame is likely to be a defect, if the count value is equal to or less than the threshold count;
• and
• (6) defect correcting the first pixel if the count value exceeds the threshold count.