Granted Patent B2

US 9,047,723 · App. 14/068,832 · Granted Jun 2, 2015

Abstract

Claims (26)

1. A method of categorizing defects in a banknote, the method comprising the steps of: receiving a quantized ultrasonic image of the banknote, where the quantized ultrasonic image comprises a plurality of points, each point having a thickness value corresponding to a normal value, a thin value, or a thick value;

identifying one or more blobs comprising contiguous points each having a thickness value corresponding to a thin value;

for each identified blob, comparing a size of the blob with a damage criterion;

ignoring the blob if the blob size does not meet the damage criterion; and

for each identified blob having a size meeting the damage criterion, categorizing the identified blob using the thickness values and locations.

2. A method according to claim 1 , wherein the step of identifying one or more blobs includes using a region growing algorithm.

3. A method according to claim 1 , wherein the step of identifying one or more blobs includes storing, for each complete blob, the blob location, size and dimensions.

4. A method according to claim 1 , wherein the step of categorizing the identified blob includes the categories of: tear, missing portion, corner fold, hole, and tape.

5. A method according to claim 1 , wherein the step of categorizing the identified blob comprises the further step of: (a) categorizing the identified 25 blob as a hole if the blob does not touch one of the edges of the banknote.

6. A method according to claim 1 , wherein the method comprises the further steps of:

identifying one or more blobs comprising contiguous points each having a thickness value corresponding to a thick value;

for each identified blob, comparing a size of the blob with a damage criterion;

ignoring the blob if the blob size does not meet the damage criterion; and

for each identified blob having a size meeting the damage criterion, categorizing the identified blob as tape if it is not connected to a blob comprising contiguous points each having a thickness value corresponding to a thin value.

7. A method according to claim 1 , wherein the method comprises 10 the further step of applying fitness rules to the categorized blobs to ascertain if the banknote should be classified as unfit.

8. A method according to claim 1 , wherein the method comprises the further step of capturing an ultrasonic image of the banknote and then creating a quantised image from the captured image prior to the step of 15 receiving a quantised ultrasonic image of the banknote.

9. A method according to claim 1 , wherein the method comprises the further step of adjusting spatial dimensions of the received image so that the received image matches spatial dimensions of a reference for that banknote.

10. A banknote validator operable to categorize defects on a banknote presented thereto, the banknote validator comprising: a banknote transport for transporting a banknote; an ultrasonic transceiver aligned with the banknote transport and for capturing a two-dimensional array of points corresponding to the banknote, each point having a point value relating to a thickness of the banknote at a spatial location on the banknote corresponding to that point; and a processor programmed to control the banknote transport and the ultrasonic transceiver, and also programmed to:

(a) quantise the captured array of points to create a quantised ultrasonic image,

(b) identify one or more blobs comprising contiguous points each having a point value corresponding to a thin value,

(c) ascertain if which identified blobs meet a damage criterion, and

(d) categorize those identified blobs meeting the damage criterion.

11. A banknote validator according to claim 10 , further comprising a banknote store.

12. A method of categorizing defects in a banknote, the method comprising the steps of: receiving an ultrasonic image of the banknote;

identifying one or more blobs having an abnormal thickness value; and

categorizing an identified blob using the thickness value and a location of that identified blob.

Assignments (10)