Digital image coin discrimination for use with consumer-operated kiosks and the like
Systems and associated methods for coin discrimination are disclosed herein. Disclosed methods for discriminating coins include recognizing strings of alphanumerical characters of the coin using Optical Character Recognition (OCR). The methods can include recognizing colors and/or reflectivity of the coin using, for example, pixel thresholding algorithms. The methods can further include adding a line to an image of the coin, and measuring angles between the line and the edges on the coin. The methods can also include generating a rectangular image of the coin using, for example, a log-polar transform, generating a series of, for example, Fourier transforms from the rectangular image, and identifying spectral peak locations and intensities in the Fourier transform results. The results of the OCR, color/reflectivity recognition, angle measurement, spectral peak location, spectral peak intensity of the coin and/or other features or aspects of coins can then be compared to known values for different coins to discriminate the coins.
1. A computer-implemented method for identifying coins, the method comprising:
obtaining a first digital image of a coin with a camera;
generating a second digital image from the first digital image, wherein the second digital image is a line image;
identifying at least one edge in the second digital image;
adding an image of a line to the second digital image;
determining an angle between the at least one edge and the image of the line; and
discriminating the coin by comparing the angle to a stored property of a coin.
2. The method of claim 1 wherein the image of the line and the at least one edge intersect.
3. The method of claim 1 , further comprising:
rotating the second digital image.
4. The method of claim 1 wherein the stored property of a coin is a first stored property of a coin, the method further comprising:
detecting at least two aspects in the second digital image;
calculating a distance between the at least two aspects; and
discriminating the coin by comparing the distance to a second stored property of a coin.
5. The method of claim 1 wherein the stored property of a coin is a first stored property of a coin, the method further comprising:
selecting a plurality of aspects in the second digital image;
counting a number of aspects; and
discriminating the coin by comparing the number to a second stored property of a coin.
6. A consumer operated coin counting system comprising:
a coin input region configured to receive a plurality of coins;
a digital camera configured to capture a first digital image of at least one coin of the plurality of coins;
a processor configured to:
generate a second digital image from the first digital image, wherein the second digital image is a line image,
identify at least one edge in the second digital image,
apply an image of a line to the second digital image, and
determine an angle between the at least one edge in the second digital image and the image of the line; and
discriminate the at least one coin by comparing the angle to a stored property of a coin.
7. The system of claim 6 wherein the stored property of a coin is a first stored property of a coin, the processor further configured to:
identify aspects in the first digital image;
determine a distance between the aspects; and
discriminate the at least one coin by comparing the distance to a second stored property of a coin.
8. The system of claim 6 wherein the stored property of a coin is a first stored property of a coin, the processor further configured to:
determine a separation between serrated lines along an edge of the at least one coin; and
discriminate the at least one coin by comparing the separation to a second stored property of a coin.
9. The system of claim 6 wherein the processor is further configured to convert individual first digital images to individual gray scale images.
10. The system of claim 6 wherein the processor is further configured to determine a diameter of the coin.
11. The system of claim 6 wherein the stored property of a coin is a first stored property of a coin, the processor further configured to:
generate third digital images from the second digital images using a log-polar mapping;
apply a Fourier-transform on the third digital images; and
discriminate the coin by comparing results of the Fourier-transform to a second stored property of a coin.
12. A processor configured to implement a method comprising:
receiving a first digital image of a coin from a camera;
generating a second digital image from the first digital image;
identifying at least one edge in the second digital image;
adding an image of a line to the second digital image;
determining an angle between the at least one edge and the image of the line; and
discriminating the coin by comparing the angle to a stored property of a coin.
13. The processor of claim 12 wherein the image of the line and the at least one edge intersect.
14. The processor of claim 12 wherein the method further comprises:
rotating the second digital image.
15. The processor of claim 12 wherein the stored property of a coin is a first stored property of a coin, and wherein the method further comprises:
detecting at least two aspects in the second digital image;
calculating a distance between the at least two aspects; and
discriminating the coin by comparing the distance to a second stored property of a coin.