Image analysis for authenticating a product
A method of authenticating a product by taking an image of the product and comparing the image with a reference image of a genuine product taken previously to determine if the products in the two images are the same. The two images are captured under substantially similar conditions so that the two images are as similar as possible prior to the comparison. The two images are processed in order to calculate for each of them a list of significant points. The significant points are compared to determine a degree of correspondence between the significant points. An answer is output indicating the authenticity of the product based on the degree of correspondence. Some of the matching significant points may be used to define a common coordinate system for the two images. The two lists of significant points may be compared in this common coordinate system.
1. A method of authenticating a product, comprising:
capturing an image of a product to be authenticated;
determining a plurality of significant points of the captured image;
comparing the plurality of significant points of the captured image of the product to be authenticated with a plurality of significant points of a previously captured reference image of a genuine product, wherein the product to be authenticated and the genuine product are located in a substantially similar position in the images from which the significant points are calculated;
aligning a plurality of said significant points of the image of the product to be authenticated with a plurality of said significant points of the image of the genuine product prior to comparing the significant points, wherein comparing the plurality of significant points of the image of the product to be authenticated with the plurality of significant points of the image of the genuine product comprises determining if a significant point of the plurality of significant points of the image of the product to be authenticated is within a defined distance of a significant point of the plurality of significant points of the image of the genuine product; and
determining a total number of significant points of the image of the product to be authenticated that are within said defined distance of a significant point of the image of the genuine product within a region of the image.
2. The method of claim 1 , wherein aligning the significant points comprises:
determining two or more matching pairs between the plurality of significant points of the image of the product to be authenticated and the plurality of significant points of the image of the genuine product; and
determining a transformation for aligning the significant points using the two or more matching pairs.
3. The method of claim 2 , wherein each of the significant points of the image of the product to be authenticated and the significant points of the image of the genuine product comprises a descriptor, and wherein determining two or more matching pairs comprises comparing the descriptors of the plurality of significant points of the image of the product to be authenticated and the plurality of significant points of the image of the genuine product.
4. The method of claim 2 , further comprising dividing the image of the product to be authenticated into a plurality of sub-regions, and aligning the plurality of significant points of the image of the product to be authenticated and the plurality of significant points of the reference image of the genuine product separately for the sub-regions.
5. The method of claim 4 , comprising determining a plurality of significant points of the image of the product to be authenticated prior to determining the sub-regions for assisting in a determination of the sub-regions.
6. The method of claim 1 , wherein comparing the plurality of significant points of the image of the product to be authenticated with the plurality of significant points of the image of the genuine product comprises determining if a significant point of the plurality of significant points of the image of the product to be authenticated is within a defined distance of a significant point of the plurality of significant points of the image of the genuine product for at least some of the significant points of the image of the product to be authenticated or for at least some of the significant points of the image of the genuine product within a region of the image.
7. The method of claim 6 , further comprising applying a function to the total number to determine an output for comparison with a threshold value to determine the authenticity of the product.
8. The method of claim 7 , wherein the function comprises dividing the total number by the total number of significant points of the image of the product to be authenticated within the region of the image or by the total number of significant points of the image of the genuine product within the region of the image to determine a ratio.
9. The method of claim 1 , wherein the product is a timepiece.
10. The method of claim 1 , wherein the captured image is a first image, and the method further comprising capturing a second image of the product for creating a composite image based on the first image and the second image for comparison with a reference image of a genuine product for authenticating the product.
11. The method of claim 10 , wherein the capturing the first image of the product is carried out when the product is illuminated from a first direction and wherein the capturing the second image of the product is carried out when the product is illuminated from a second direction, wherein the second direction is different from the first direction.
12. The method of claim 10 , wherein the capturing the first image is carried out at a first exposure time, and wherein the capturing the second image is carried out at a second exposure time, wherein the first exposure time is different from the second exposure time.
13. The method of claim 10 , further comprising receiving imaging instructions comprising the conditions for capturing the image or images of the product to be authenticated, and capturing the image or images of the product according to the imaging instructions.
14. The method of claim 13 , wherein the imaging instructions convey substantially similar or the same conditions under which the reference image or images of a genuine product were captured at an earlier point in time so that the product to be authenticated can be imaged under substantially similar or the same conditions as the genuine product.