A system for inspecting a product, comprising: a scanner configured to scan across the product and to generate an image of the product, the image including a matrix of pixels each having a grayscale value, a microprocessor to calculate a reference grayscale value associated with each of the pixels in the image, the reference grayscale value includes an average of the grayscale values of pixels located adjacent to the each pixel, and a comparing module to compare the grayscale value of each of the pixels in the image with at least one threshold associated with the each pixel, wherein: the scanner comprises a first scanner and a second scanner, the first scanner is configured to scan a first layer of the product and to generate a first image including a matrix of pixels each having a grayscale value, the second scanner is configured to scan a second layer of the product and to generate a second image, the second image including a matrix of pixels each having grayscale value, the scanner includes a number of scanning units (CHO to CH17) arranged in a first direction, each of the scanning units (CHO to CH17) including a number of complementary metal-oxide semiconductor (CMOS) sensor cells, characterized in that: the comparing module is configured to compare a first amount of offset from the at least one threshold associated with a pixel in the first image with a second amount of offset from the at least one threshold associated with a corresponding pixel in the second image so as to determine a specific defective layer. a scanner configured to scan across the product and to generate an image of the product, the image including a matrix of pixels each having a grayscale value, a microprocessor to calculate a reference grayscale value associated with each of the pixels in the image, the reference grayscale value includes an average of the grayscale values of pixels located adjacent to the each pixel, and a comparing module to compare the grayscale value of each of the pixels in the image with at least one threshold associated with the each pixel, wherein: the scanner comprises a first scanner and a second scanner, the first scanner is configured to scan a first layer of the product and to generate a first image including a matrix of pixels each having a grayscale value, the second scanner is configured to scan a second layer of the product and to generate a second image, the second image including a matrix of pixels each having grayscale value, the scanner includes a number of scanning units (CHO to CH17) arranged in a first direction, each of the scanning units (CHO to CH17) including a number of complementary metal-oxide semiconductor (CMOS) sensor cells, characterized in that: the comparing module is configured to compare a first amount of offset from the at least one threshold associated with a pixel in the first image with a second amount of offset from the at least one threshold associated with a corresponding pixel in the second image so as to determine a specific defective layer. the scanner comprises a first scanner and a second scanner, the first scanner is configured to scan a first layer of the product and to generate a first image including a matrix of pixels each having a grayscale value, the second scanner is configured to scan a second layer of the product and to generate a second image, the second image including a matrix of pixels each having grayscale value, the scanner includes a number of scanning units (CHO to CH17) arranged in a first direction, each of the scanning units (CHO to CH17) including a number of complementary metal-oxide semiconductor (CMOS) sensor cells, characterized in that: the comparing module is configured to compare a first amount of offset from the at least one threshold associated with a pixel in the first image with a second amount of offset from the at least one threshold associated with a corresponding pixel in the second image so as to determine a specific defective layer.