System and method for identifying defects in a material

1. A computerized method for identifying a defect in a material, comprising:

generating, by a computing device, a preprocessed image based on an original image of a material;

dividing, by the computing device, the preprocessed image into a set of sub-images;

for a first sub-image in the set of sub-images:

determining, by the computing device, whether the first sub-image includes a feature, wherein the feature is a candidate portion of a defect in the material; and

if the first sub-image includes the feature, adding, by the computing device, the first sub-image to a set of feature sub-images;

selecting, by the computing device, a chained feature based on the set of feature sub-images, wherein the chained feature comprises one or more features that represent candidate portions of a same defect in the material; and

identifying, by the computing device, a defect in the material based on the chained feature and the original image, comprising calculating a remaining portion of the defect based on the chained feature,

wherein identifying the defect comprises:

selecting a pair of chained features comprising the chained feature;

determining if the pair of chained features satisfies a first criterion indicative of the pair of chained features being on a same defect in the material; and

calculating a remaining portion of the same defect between the pair of the chained features.

2. The method of claim 1 , wherein generating the preprocessed image comprises:

generating a filtered image, comprising removing one or more features using a filter; and

generating the preprocessed image by subtracting the filtered image from the original image to expose the one or more features in the original image.

3. The method of claim 1 , wherein the preprocessed image is the original image.

4. The method of claim 1 , wherein the preprocessed image exposes one or more features of the material.

5. The method of claim 1 , wherein the preprocessed image comprises dark pixels and light pixels, wherein the dark pixels and the light pixels are identified based on a grey-level threshold.

6. The method of claim 5 , wherein determining whether the sub-image includes the feature comprises executing a line fitting algorithm using the light pixels, the dark pixels, or both, in the sub-image.

7. The method of claim 1 , further comprising:

determining the feature satisfies a first set of criterions; and

determining the chained features and the calculated remaining portion of the defect satisfy a second set of criterions.

8. The method of claim 1 , wherein selecting the chained feature comprises:

selecting a feature sub-image from the set of feature sub-images;

identifying one or more sub-images that border the selected feature sub-image, each identified sub-image including a feature; and

generating a chained feature comprising the selected feature sub-image and a sub-image from the one or more identified sub-images based on one or more constraints.

9. The method of claim 8 , wherein the one or more constraints comprises a position, an orientation, or both, of the one or more features.

10. The method of claim 1 , wherein the first criterion is based on a distance between the pair of chained features, an end direction of each feature in the pair of chained features, a turning angle of each feature in the pair of chained features, a length of each feature in the pair of chained features, or any combination thereof.

11. A computer program product, tangibly embodied in a non-transitory computer readable medium, the computer program product including instructions being configured to cause a data processing apparatus to:

generate a preprocessed image based on an original image of a material;

divide the preprocessed image into a set of sub-images;

for a first sub-image in the set of sub-images:

determine whether the first sub-image includes a feature, wherein the feature is a candidate portion of a defect in the material; and

if the first sub-image includes the feature, add the first sub-image to a set of feature sub-images;

select a chained feature based on the set of feature sub-images, wherein the chained feature comprises one or more features that represent candidate portions of a same defect in the material; and

identify a defect in the material based on the chained feature and the original image, comprising calculating a remaining portion of the defect based on the chained feature,

wherein identifying the defect comprises:

selecting a pair of chained features comprising the chained feature;

determining if the pair of chained features satisfies a first criterion indicative of the pair of chained features being on a same defect in the material; and

calculating a remaining portion of the same defect between the pair of the chained features.

12. An apparatus for identifying a defect in a material, comprising:

a preprocessing module configured to generate a preprocessed image based on an original image of a material;

a strong feature detection module in communication with the preprocessing module configured to:

divide the preprocessed image into a set of sub-images; and

for a first sub-image in the set of sub-images:

determine whether the first sub-image includes a feature, wherein the feature is a candidate portion of a defect in the material; and

if the first sub-image includes the feature, add the first sub-image to a set of feature sub-images; and

a weak feature detection module in communication with the strong feature detection module configured to:

select a chained feature based on the set of feature sub-images, wherein the chained feature comprises one or more features that represent candidate portions of a same defect in the material; and

identify a defect in the material based on the chained feature and the original image, comprising calculating a remaining portion of the defect based on the chained feature,

wherein identifying the defect comprises:

selecting a pair of chained features comprising the chained feature;

determining if the pair of chained features satisfies a first criterion indicative of the pair of chained features being on a same defect in the material; and

calculating a remaining portion of the same defect between the pair of the chained features.