Method and apparatus for analyzing an image

• US 6,341,182 B1
• Filed: 08/21/1998
• Issued: 01/22/2002
• Est. Priority Date: 09/11/1997
• Status: Expired due to Term

• Current Assignee: Randox Laboratories Limited
• Original Assignee: Randox Laboratories Limited
• Inventors: McConnell, Robert Ivan, Fitzgerald, Stephen Peter, Lamont, John Victor
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US09/138,009
• Time in Patent Office: 1,250 Days
• Field of Search: 382/270, 382/273, 382/274, 382/275, 382/132, 382/133, 382/128, 382/129, 382/172, 382/173, 382/195, 382/205, 382/256, 382/257, 382/191, 382/254, 382/308, 702/22
• US Class Current: 382/273
• CPC Class Codes: G01N 15/1433 using image recognition
• CPC Class Codes: G06T 2207/20036 Morphological image processing
• CPC Class Codes: G06T 2207/30072 Microarray; Biochip, DNA array; Well plate
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G06T 7/155 involving morphological operators
• CPC Class Codes: G06T 7/194 involving foreground-background segmentation

Abstract

A method of analysing an image to obtain an image value. The image comprises a defined array of pixel values. The method comprises

(1) determining the highest pixel value in the image;

(2) calculating a lower threshold pixel value from the highest pixel value determined in step (1) in accordance with a predetermined algorithm; and

(3) obtaining the image value by statistically analysing the pixel values in the image which lie in a range defined by the lower threshold pixel value calculated in step (2).

Claims

1. A method of analyzing an image to obtain an image value, said image comprising a defined array of pixel values, said method comprising

(1) determining a highest pixel value in said image;

(2) calculating a lower threshold pixel value from said highest pixel value determined in said step (1) in accordance with a predetermined algorithm; and

(3) obtaining said image value that represents a brightness of the image by statistically analyzing said pixel values in said image which lie in a range defined by said lower threshold pixel value calculated in said step (2).

2. A method according to claim 1, further comprising calculating an upper threshold pixel value from said highest pixel value determined in said step (1) in accordance with a second predetermined algorithm, wherein step (3) comprises statistically analysing pixel values in said image which lie in a range defined by said upper and said lower pixel threshold values.

3. A method according to claim 1, wherein said lower threshold pixel value is calculated as a predetermined percentage of said highest pixel value determined in said step (1).

4. A method according to claim 3, wherein said lower threshold pixel value is between 50% and 90% of said highest pixel value determined in said step (1).

5. A method according to claim 4, wherein said lower threshold pixel value is substantially 80% of said highest pixel value determined in said step (1).

6. A method according to claim 2, wherein said upper threshold pixel value is between 97% and 99% of said highest pixel value determined in said step (1).

7. A method according to claim 6, wherein said upper threshold pixel value is substantially 98% of said highest pixel value determined in said step (1).

8. A method according to claim 1, further comprising removing background from said pixel values.

9. A method according to claim 8, wherein said background is removed by a process selected from erosion, dilation, opening and thresholding.

11. A method according to claim 1, further comprising detecting radiation from an original image to generate said array of pixel values.

12. A method according to claim 1, further comprising previously defining said defined array of pixel values by reviewing an original array of pixel values, and removing one or more of said highest pixel values in said original array of pixel values.

13. A method according to claim 1, wherein said image value is obtained in said step (3) by calculating the average of said pixel values.

14. A method according to claim 1, wherein said image has been obtained from a reaction site containing a reactive species which reacts with an analyte and which has been exposed to a test sample.

10. A method of analyzing an image to obtain a plurality of image values, said image comprising an array of pixel values, said method comprising dividing said image into a plurality of regions, and obtaining an image value from each region by

(1) determining a highest pixel value in said image region;

(2) calculating a lower threshold pixel value from said highest pixel value determined in said step (1) in accordance with a predetermined algorithm; and

(3) obtaining said image value that represents a brightness of the image by statistically analyzing said pixel values in said region which lie in a range defined by said lower threshold pixel value calculated in said step (2).

15. A method of analyzing a localized reaction site containing a reactive species which react with an analyte and which has been exposed to a test sample, the method comprising detecting radiation from said reaction site to generate an image comprising an array of pixel values, said radiation being indicative of the presence or absence of said analyte in said test sample;

and analyzing said image by

(1) determining a highest pixel value in said image;

(2) calculating a lower threshold pixel value form said highest pixel value determined in said step (1) in accordance with a predetermined algorithm; and

(3) obtaining said image value that represents a brightness of the image by statistically analyzing said pixel values in said image which lie in a range defined by said lower threshold pixel value calculated in said step (2), thereby obtaining an image value indicative of the presence or absence of the analyte in the test sample.

17. A method according to claim 15, wherein said reaction site is located on a solid state substrate, and wherein said reactive species comprises a ligand covalently bonded to said substrate.

18. A method according to claim 17, wherein a surface of said substrate outside said reaction site is inert with respect to said analyte.

19. A method according to claim 15, wherein said radiation comprises one selected from chemiluminescent, bioluminescent and fluorescent radiation emitted from said reaction site.

16. A method of analyzing a plurality of localized reaction sites, each containing a reactive species which reacts with a respective analyte and each having been exposed to a test sample, the method comprising detecting radiation from said reaction sites to generate an image comprising an array of pixel values, said radiation from each said reaction site being indicative of the presence or absence of a respective analyte in said test sample;

dividing said image into a plurality of image regions each corresponding with a respective one of said reactions sites; and

analyzing each image region by

(1) determining a highest pixel value in said image region;

(2) calculating a lower threshold pixel value from said highest pixel value determined in said step (1) in accordance with a predetermined algorithm; and

(3) obtaining said image value that represent a brightness of the image by statistically analyzing pixel values in said image region which lie in a range defined by said lower threshold pixel value calculated in said step (2), thereby obtaining a plurality of image values each being indicative of the presence or absence of a respective analyte in the test sample.

20. A method of performing an assay, the method comprising exposing a reaction site to a test sample, said reaction site containing a reactive species which reacts with a respective analyte;

and analyzing said reaction site by detecting radiation from said reaction site to generate an image comprising an array of pixel values, said radiation being indicative of the presence or absence of said analyte in said test sample; and

analyzing said image by

(1) determining a highest pixel value in said image;

(2) calculating a lower threshold pixel value from said highest pixel value determined in said step (1) in accordance with a predetermined algorithm; and

(3) obtaining said image value that represents a brightness of the image by statistically analyzing said pixel values in said image which lie in a range defined by said lower threshold pixel value calculated in said step (2), thereby obtaining an image value indicative of the presence or absence of the analyte in the test sample.

21. Apparatus for analyzing an image to obtain an image value, said image comprising a defined array of pixel values, said apparatus comprising

(1) means for determining a highest pixel value in said image;

(2) means for calculating a lower threshold pixel value from said highest pixel value in accordance with a predetermined algorithm; and

(3) means for obtaining said image that represents a brightness of the image value by statistically analyzing pixel values in said image which lie in a range defined by said lower threshold pixel value.

22. Apparatus for analyzing a reaction site containing a reactive species which reacts with an analyte and which has been exposed to a test sample, said apparatus comprising means for detecting radiation from said reaction site to generate an image comprising an array of pixel values, said radiation from said reaction site being indicative of the presence or absence of a respective analyte in said test sample;

(1) means for determining a highest pixel value in said image;

(2) means for calculating a lower threshold pixel value from said highest pixel value in accordance with a predetermined algorithm; and

(3) means for obtaining said image value that represents a brightness of the image by statistically analyzing pixel values in said image which lie in a range defined by said lower threshold pixel value, thereby obtaining one or more image values each being indicative of the presence or absence of a respective analyte in the test sample.