MACHINE IMAGING APPARATUS AND METHOD FOR DETECTING FOREIGN MATERIALS

• US 20090080706A1
• Filed: 09/26/2007
• Published: 03/26/2009
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: Industry Vision Automation Corporation
• Original Assignee: Industry Vision Automation Corporation
• Inventors: CHEN, Xin, JIN, Fenghua, ZHU, Bin, JING, Hansong, TAO, Yang
• Granted Patent: US 8,351,672 B2
• Time in Patent Office: Days
• US Class Current: 382/110
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 23/083 the radiation being X-rays
• CPC Class Codes: G01N 33/02 Food
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/10116 X-ray image
• CPC Class Codes: G06T 2207/30128 Food products
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: G06V 20/68 Food, e.g. fruit or vegetables

Abstract

A combined X-ray and laser 3D imaging system for food safety inspection, which uses a 3D laser subsystem to get accurate depth information, which is further combined with an x-ray image to achieve accurate physical contamination detection in poultry and other meat products. A unique calibration model is used to calibrate the x-ray and laser 3D imaging systems at the same time. And a nested multi-thread software structure is implemented to prevent data conflict and ensure fully use of system resources during the physical contamination detection of the poultry and other meat products.

Claims

1. An inspection apparatus, comprising;

a housing including;

an x-ray source for generating an x-ray beam;

a first laser for generating a first laser beam; and

a second laser for generating a second laser beam,

2. The inspection apparatus according to claim 1,

wherein the first and second lasers are placed on each side of said x-ray source,

wherein said x-ray beam and said first and second laser beams are substantially coplanar;

and

wherein the first and second laser beams overlap each other.

3. The inspection apparatus according to claim 2, wherein

said housing further includes:

a first window,

wherein said x-ray beam and said first and second laser beams pass through said first window.

4. The inspection apparatus according to claim 3, wherein

said housing further includes:

a pair of cameras;

wherein each camera of said pair of cameras is located on one side of said x-ray source, respectively.

5. The inspection apparatus according to claim 4, wherein

said housing further includes:

a second window; and

a third window,

wherein one camera of said pair of cameras is oriented towards said second window and the other camera of said pair of cameras is oriented towards said third window.

6. The inspection apparatus according to claim 4, further comprising:

a conveyor for carrying object(s) for inspection; and

an x-ray line scan camera that is placed under the conveyor and is aligned with the x-ray beam for capturing an x-ray image of said object(s) radiated by the x-ray beam, and

wherein said pair of cameras capture image data of said object(s) when irradiated by said first and second laser beams.

7. The inspection apparatus according to claim 5, wherein said first and second laser sources are each titled at an angle to allow said pair of cameras to capture respective sides of the object(s) illuminated by said first and second laser sources.

8. The inspection apparatus according to claim 6, further comprising:

an encoder that is attached to said conveyer and sends conveyor movement signals to a computer; and

a rejection device for removing object(s) off said conveyor;

said computer including;

means for receiving said signals from said encoder;

means for synchronizing said pair of cameras and said x-ray line scan camera based on said received encoder signals;

means for receiving image data of said object(s) from said pair of cameras and an x-ray image from said x-ray line scan camera;

means for generating an x-ray image of said object(s);

means for calculating intensity, inverse intensity, and x-ray absorption coefficient of said x-ray image;

means for generating a depth image of said object(s), said depth image having a thickness intensity;

means for calculating a virtual x-ray intensity image of said object(s), wherein said virtual x-ray image is obtained through a regression analysis based on said x-ray absorption coefficient and said thickness intensity;

means for subtracting said inverse intensity of said x-ray image from said virtual x-ray image to detect bone, bone fragments or foreign materials in the object(s);

means for generating a rejection signal when it is detected that said object(s) include bones, bone fragments or foreign materials;

wherein the rejection signal is sent by said computer to said rejection device to remove said object(s) detected with bone, bone fragments or foreign materials from said conveyor.

9. A calibration model for calibrating said pair of cameras and said x-ray line scan camera of claim 6, said calibration model comprising:

two plates each with calibration holes,

wherein pins are inserted in the calibration holes of the two plates, and wherein the two plates are used to calibrate said pair of cameras and the pins are used to calibrate the x-ray line scan camera.

10. A method of using the calibration model of claim 9 to calibrate said pair of cameras and the x-ray line scan camera, comprising the steps of:

aligning the calibration model with the first and second laser beams and the x-ray fan beam;

using said encoder to synchronize said pair of cameras and the x-ray scan camera to capture images by said pair of cameras and said x-ray line scan camera of said calibration model when it is moving on said conveyor; and

using said captured images of said calibrating model to calibrate said pair of cameras and said x-ray line scan camera.

11. A imaging system comprising:

an image acquisition module for acquiring x-ray and laser images of object(s), said image acquisition module including a laser imaging module and an x-ray imaging module, each of said laser imaging module and said x-ray imaging module including a plurality of cameras for capturing respective laser and x-ray images of said object(s) at the same time,

a conveyor control module for controlling the speed of a conveyor on which said object(s) are placed;

an image processing module for processing the laser and x-ray image data captured by the image acquisition module to determine if said object(s) are defective;

a rejection module for dispatching a control signal to a rejection mechanism to reject the defective object(s) from said conveyor; and

a control module for controlling the interaction between said image acquisition module, said conveyor control module, said image processing module and said rejection module.

12. The imaging system according to claim 11, wherein said rejection module includes a user interface module for displaying related statistics regarding defective samples.

13. The imaging system according to claim 11, wherein said conveyor control module and said image acquisition module are synchronized by the control module in order to increase the throughput of the said imaging system.

14. The imaging system according to claim 11, wherein said image processing module further converts said laser image into a pseudo x-ray image based on both the acquired laser and x-ray images, compensates for the thickness of said pseudo x-ray image, extracts a region of interest(s) from said compensated pseudo x-ray image to create a blob image(s), and classifies said blob image(s) as normal or abnormal.

15. The imaging system according to claim 11, wherein said image acquisition module further includes a buffer memory for storing said capturing laser and x-ray images.

16. The imaging system according to claim 15, wherein said control module compares free buffer space of said buffer memory to a predetermined threshold and a sends a control signal to said conveyor control module to decrease the speed of said conveyor when said free buffer space of said buffer memory is below said predetermined threshold.

17. The imaging system according to claim 16, wherein at least one of said image acquisition module, said conveyor control module, said image processing module, said rejection module, and said control module implements a multithread model, which includes a scheduler thread and a worker thread.

18. The imaging system according to claim 17, wherein said scheduler thread passes newly arrived image data to a worker thread, and said worker thread enters a busy state to process the passed image data, wherein the response time of the scheduler thread is less than the processing time of the worker thread.

19. The imaging system according to claim 18, wherein said threads of said multithread model are organized in a nested manner.

20. The imaging system according to claim 18, wherein said thread are grouped into a locator group, which is to used determine the location of each sample and a probe group, which is set to search for physical hazards or bone fragments in each sample based on the information embedded in the x-ray and laser range images.