Method and apparatus for making and processing aberration measurements

• US 8,254,724 B2
• Filed: 11/06/2008
• Issued: 08/28/2012
• Est. Priority Date: 11/06/2008
• Status: Active Grant

• Current Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Original Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Inventors: Allred, Lloyd G.
• Primary Examiner(s): Zarka, David
• Application Number:
  US12/266,019
• Publication Number:
  US 20100111421A1
• Time in Patent Office: 1,391 Days
• Field of Search: 382/288
• US Class Current: 382/288
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: G06T 7/66 of image moments or centre of gravity

Abstract

A method for determining a centroid coordinate of an image spot, comprising a) determining a search region having a border, b) identifying a first pixel in the search region, the pixel having a first intensity value, c) determining an upper threshold intensity value greater than the first intensity value, d) searching for a second pixel within the search region having an intensity value that is greater than the upper threshold intensity value, and e) upon finding the second pixel, designating the first pixel an integration region center.

Claims

1. A method for determining a centroid coordinate of an image spot in a system for measuring an ocular aberration, comprising:

a) determining a search region having a border;

b) identifying a first pixel in the search region, the first;

pixel having a first intensity value;

c) determining an upper threshold intensity value greater than the first intensity value;

d) searching for a second pixel within the search region having an intensity value that is greater than the upper threshold intensity value;

e) upon finding the second pixel, designating the first pixel an integration region center; and

f) determining a lower threshold intensity value less than the first intensity value, and wherein step (e) is performed only if at least one intensity values between the first pixel and the second pixel is less than the lower threshold intensity value.

2. The method of claim 1, further comprising identifying a radius, r, of the integration region equal to a distance between the first pixel to the second pixel.

3. The method of claim 1, further comprising, provided that none of the intensity values between the first pixel and the second pixel is less than the lower threshold intensity value, designating the second pixel as the first pixel having a first intensity value and repeating steps (c)-(f).

4. The method of claim 1, provided that no pixel within the search region has an intensity value that is greater than the upper threshold intensity value, designating the first pixel an integration region center, and further comprising identifying a radius, r, of an integration region equal to the distance from the first pixel to the border.

5. The method of claim 1, wherein the search region is smaller than a distance between neighbor spots.

6. A system for measuring an ocular aberration, comprising:

an aberrometer including a lenslet component for forming an image containing an array of image spots;

a sensor positioned to detect the image spot array;

a processor component including executable software that provides an instruction for determining a centroid coordinate of each of said image spots, wherein the instruction comprises;

a) determining a search region having a border;

b) identifying a first pixel in the search region, the first pixel having a first intensity value;

c) determining an upper threshold intensity value greater than the first intensity value;

d) searching for a second pixel within the search region having an intensity value that is greater than the upper threshold intensity value; and

e) upon finding the second pixel, designating the first pixel an integration region center; and

f) determining a lower threshold intensity value less than the first intensity value, and wherein step (e) is performed only if at least one intensity values between the first pixel and the second pixel is less than the lower threshold intensity value.

7. The system of claim 6, wherein the instruction further comprises identifying a radius, r, of an integration region equal to a distance between the first pixel to the second pixel.

8. The system of claim 6, wherein the instruction is adapted such that, provided that none of the intensity values between the first pixel and the second pixel is less than the lower threshold intensity value, designating the second pixel as the first pixel and repeating steps (b)-(f).