METHOD AND APPARATUS FOR LABEL DETECTION

• US 20180314908A1
• Filed: 05/01/2017
• Published: 11/01/2018
• Est. Priority Date: 05/01/2017
• Status: Active Application

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Inventors: Lam, Joseph
• Application Number:
  US15/583,786
• Publication Number:
  US 20180314908A1
• Time in Patent Office: Days
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes
• CPC Class Codes: G06V 10/22 by selection of a specific region containing or referencing a pattern; Locating or processing of specific regions to guide the detection or recognition
• CPC Class Codes: G06V 10/751 Comparing pixel values or logical combinations thereof, or feature values having positional relevance, e.g. template matching

Abstract

A method of label detection includes: obtaining a template for a label having a sub-region containing a visual feature, the template defining (i) a label geometry, and (ii) a sub-region geometry relative to the label geometry; obtaining an image; generating a feature mask from the image, the feature mask indicating areas of the image containing the visual feature; for each of a plurality of template positions within the feature mask, determining a score based on a degree of matching between the sub-region geometry and a respective subset of the areas; and selecting and presenting a label location within the image based on the scores.

Claims

1. A method of label detection by an imaging controller, comprising:

obtaining a template for a label having a sub-region containing a visual feature, the template defining (i) a label geometry, and (ii) a sub-region geometry relative to the label geometry;

obtaining an image;

generating a feature mask from the image, the feature mask indicating areas of the image containing the visual feature;

for each of a plurality of template positions within the feature mask, determining a score based on a degree of matching between the sub-region geometry and a respective subset of the areas; and

selecting and presenting a label location within the image based on the scores.

2. The method of claim 1, wherein determining a score comprises:

generating a score heat map corresponding to the image, the score heat map containing, for each of the positions, the score determined for that position.

3. The method of claim 2, wherein the selecting includes identifying respective local maxima within the score heat map for each of a plurality of windows within the heat map.

4. The method of claim 2, wherein the selecting includes applying a threshold to the scores.

5. The method of claim 1, wherein the presenting comprises:

presenting the image on a display, overlaid with a bounding box indicating the label location.

6. The method of claim 1, wherein the visual feature includes at least one of text and a barcode.

7. The method of claim 1, the template defining a plurality of sub-region geometries relative to the label geometry.

8. The method of claim 7, the template further defining a tolerance for each of the sub-region geometries relative to the label geometry;

wherein determining the score for each of the template positions comprises;

selecting a plurality of sub-region geometries according to the tolerance;

determining a degree of matching for each of the sub-region geometries; and

determining the score based on the greatest degree of matching for each sub-region geometry.

9. The method of claim 1, wherein the obtaining comprises:

obtaining the template and a further template defining (i) a further label geometry, and (ii) a further sub-region geometry relative to the further label geometry;

each of the template and the further template also defining a label type; and

repeating the determining, the selecting and the presenting for each of the templates.

10. A server for detecting labels, comprising:

a memory storing a template for a label having a sub-region containing a visual feature, the template defining (i) a label geometry, and (ii) a sub-region geometry relative to the label geometry; and

an imaging controller comprising;

a mask generator configured to;

obtain an image; and

generate a feature mask from the image, the feature mask indicating areas of the image containing the visual feature;

a score generator configured, for each of a plurality of template positions within the feature mask, to determine a score based on a degree of matching between the sub-region geometry and a respective subset of the areas; and

a selector configured to select and present a label location within the image based on the scores.

11. The server of claim 10, the score generator configured to determine a score by generating a score heat map corresponding to the image, the score heat map containing, for each of the positions, the score determined for that position.

12. The server of claim 11, the selector configured to identify respective local maxima within the score heat map for each of a plurality of windows within the heat map.

13. The server of claim 11, the selector further configured to apply a threshold to the scores.

14. The server of claim 10, the selector further configured to present the label locations by presenting the image on a display, overlaid with a bounding box indicating the label location.

15. The server of claim 10, wherein the visual feature includes at least one of text and a barcode.

16. The server of claim 10, the template defining a plurality of sub-region geometries relative to the label geometry.

17. The server of claim 16, the template further defining a tolerance for each of the sub-region geometries relative to the label geometry;

the score generator further configured to determine the score for each of the template positions by;

selecting a plurality of sub-region geometries according to the tolerance;

determining a degree of matching for each of the sub-region geometries; and

determining the score based on the greatest degree of matching for each sub-region geometry.

18. The server of claim 10, the score generator further configured to:

prior to determining the score, obtain the template and a further template defining (i) a further label geometry, and (ii) a further sub-region geometry relative to the further label geometry;

each of the template and the further template also defining a label type; and

repeat the determining, the selecting and the presenting for each of the templates.