METHOD, APPARATUS AND PROGRAM PRODUCT FOR SEARCHING KNOTS IN WOOD

• US 20060262972A1
• Filed: 05/16/2006
• Published: 11/23/2006
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Meinan Machinery Works, Inc.
• Original Assignee: Meinan Machinery Works, Inc.
• Inventors: Hiraoka, Noriyuki
• Granted Patent: US 7,778,458 B2
• Time in Patent Office: Days
• US Class Current: 382/141
• CPC Class Codes: B07C 5/14 Sorting timber or logs , e.g. tree trunks, beams, planks or the like
• CPC Class Codes: B07C 5/3422 using video scanning devices, e.g. TV-cameras
• CPC Class Codes: G01N 21/8986 Wood
• CPC Class Codes: G01N 33/46 Wood
• CPC Class Codes: G06T 2207/30161 Wood; Lumber
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/64 of convexity or concavity
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components

Abstract

The photographing means of the present apparatus photographs a piece of wood, while the image processing means calculates degrees of circularity from the photographed images of the piece of wood, and detects images with significant degrees of circularity as knots. In addition, the image processing means 1 clips a portion including a knot from the photographed image of the piece of wood, deems a portion clipped at a predetermined threshold among the color spaces of each pixel of the clipped portions to be a blackened portion, and determines black portions with a high proportion of a number of pixels of the blackened portion to the number of pixels of the clipped portion of the knot as dead knots.

Claims

1. A method for searching knots in wood comprising:

photographing a piece of wood by a photographing unit;

calculating degrees of circularity of each figure in the photographed images of the piece of wood; and

detecting, among the figures, a figure with a significant degree of circularity as a knot.

2. The method according to claim 1, wherein the calculating extracts a figure with a significant degree of circularity among the figures and deems the extracted figure as a knot candidate;

clips at least a partial image including the knot candidate from the photographed image of the piece of wood;

varies color shading threshold levels for the clipped partial image to obtain a threshold level where the degree of circularity and size stability are both maximum; and

determines a configuration of the knot candidate at the obtained threshold level.

3. The method according to claim 2, wherein the calculating varies the color shading threshold levels of the photographed image of the piece of wood to obtain degrees of circularity of each figure in the photographed image;

multiplies the photographed image of each threshold level by coefficients derived from the obtained degrees of circularity; and

integrates the images respectively calculated for each threshold level; and

deems the integrated image to be the knot candidate.

4. The method according to claim 1, wherein the calculating extracts a figure with a significant degree of circularity among the figures and deems the extracted figure as a knot candidate;

clips at least a portion including the knot candidate from the photographed image;

deems a portion clipped at a predetermined threshold among the color spaces of each pixel of the clipped portions to be a blackened portion; and

determines, as a dead knot, the blackened portion with a high proportion of the number of pixels of the blackened portion to the number of pixels of the knot candidate.

5. The method according to claim 1, further comprising

performing smoothing on color shadings that are larger than knots on the photographed image of the piece of wood, and

wherein the calculating calculates degrees of circularity from the smoothed images and deems a figure with a high degree of circularity to be the knot candidate.

6. An apparatus for searching knots in wood, comprising:

a photographing unit for photographing pieces of wood;

an image processing unit for calculating degrees of circularity of each figure in the photographed images of the piece of wood and detecting, among the figures, a figure images with significant degrees of circularity as a knot.

7. The apparatus according to claim 6, wherein the image processing unit extracts a figure with a significant degree of circularity among the figures, deems the extracted figure as a knot candidate, clips at least a partial image including the knot candidate from the photographed image of the piece of wood, varies color shading threshold levels for the clipped partial image to obtain a threshold level where the degree of circularity and size stability are both maximum;

and determines a configuration of the knot candidate at the obtained threshold level.

8. The apparatus according to claim 7, wherein the image processing unit varies the color shading threshold levels of the photographed images of the piece of wood to obtain degrees of circularity of each figure;

multiplies the photographed image of each threshold level by coefficients derived from the obtained degrees of circularity; and

integrates the images respectively calculated for each threshold level; and

deems the integrated image is deemed to be the knot candidate.

9. The method according to claim 6, wherein the image processing unit extracts a figure with a significant degree of circularity among the figures and deems the extracted figure as a knot candidate;

clips at least a partial image including the knot candidate from the photographed image;

deems a partial image clipped at a predetermined threshold among the color spaces of each pixel of the clipped partial images to be a blackened portion; and

determines, as dead knots, black portions with a high proportion of a number of pixels of the blackened portion to the number of pixels of the knot candidate.

10. The apparatus according to claim 6, further comprising

a smoothing unit for performing smoothing on color shadings that are larger than knots on the photographed images of the piece of wood and

wherein the image processing unit calculates degrees of circularity from the smoothed images and deems a figure with a high degrees of circularity to be the knot candidate.

11. A program product for enabling a computer to function as image processing apparatus comprising:

a unit for calculating degrees of circularity from photographed images of the piece of wood and detecting images with significant degrees of circularity as knots.

12. The program product according to claim 11, wherein

the unit deems extracts a figure with a significant degree of circularity among the figures and deems the extracted figure as a knot candidate, clips at least a partial image including the knot candidate from the photographed image of the piece of wood and varies color shading threshold levels for the clipped figure to obtain a threshold level where the degree of circularity and size stability are both maximum;

and determines a configuration of the knot candidate at the obtained threshold level.

13. The program product according to claim 12, wherein the unit varies the color shading threshold levels of the photographed image of the piece of wood to obtain degrees of circularity of each figure in the photographed image, multiplies the photographed image of each threshold level by coefficients derived from the obtained degrees of circularity, and integrates the images respectively calculated for each threshold level;

and deems the integrated image to be the knot candidate.

14. The program product according to claim 11, wherein the unit extracts a figure with a significant degree of circularity among the figures and deems the extracted figure as a knot candidate;

clips at least a partial image including the knot candidate from the photographed image;

deems a partial image clipped at a predetermined threshold among the color spaces of each pixel of the clipped portions to be a blackened portion; and

determines, as dead knots, black portions with a high proportion of a number of pixels of the blackened portion to the number of pixels of the knot candidate.

15. The program product according to claim 11, further comprising

a unit for performing smoothing on color shadings that are larger than knots on the photographed images of the piece of wood and

wherein the unit for calculating calculates degrees of circularity from the smoothed images and deems a figure with a high degree of circularity to be the knot candidate.