# US 8,464,950 B2 · Fast vision system

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- Number: US 8,464,950 B2
- Document ID: US8464950B2
- Status: Granted
- Kind: B2
- Application number: 12/341,192
- Filed: 2008-12-22
- Published: 2010-06-24
- Granted: 2013-06-18
- Earliest claimed: 2008-12-22
- Assignees: Cognex Corporation
- Applicants: Sateesha Nadabar; William Equitz
- Inventors: Sateesha Nadabar; William Equitz
- Web page: https://patentgrep.com/patent/US8464950B2

## CPC

- G06K 7/10544: {by scanning of the records by radiation in the optical part of the electromagnetic spectrum}
- G02B 7/09: adapted for automatic focusing or varying magnification
- G06K 7/10722: {Photodetector array or CCD scanning}
- G06K 7/10811: {Focalisation}
- G06K 7/10831: {Arrangement of optical elements, e.g. lenses, mirrors, prisms (optical elements per se G02B)}
- H04N 23/67: Focus control based on electronic image sensor signals
- H04N 23/743: Bracketing, i.e. taking a series of images with varying exposure conditions
- G06K 2207/1013: Multi-focal
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A method and apparatus for performing a vision process using a camera having a multi-focus lens having a lens field of view where the lens can be set at different focus positions the method comprising the steps of positioning at least one of the camera and an item to be imaged so the lens field of view is directed at the item to be imaged, obtaining a plurality of images where each image is obtained with the lens focus at a different position and after each image is obtained, attempting to perform the machine vision process using the image irrespective of whether or not the lens was focused when the image was obtained.

## Claims

### Claim 1

A method for performing a vision process using a camera having a multi-focus lens having a lens field of view where the lens can be set at different focus positions the method comprising the steps of:
positioning at least one of the camera and a symbol to be imaged so the lens field of view is directed at the symbol to be imaged;
setting an image formation setting;
obtaining a subset of images at each of a plurality of different lens focus positions where the image formation setting is different for each of the images obtained at each lens focus position; and
after each image is obtained and while obtaining additional images, attempting to perform the vision process on the images;
wherein the vision process includes one of locating a symbol in obtained images and decoding a symbol in obtained images.

### Claim 2 (depends on 1)

The method of claim 1 wherein the focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the step of obtaining a plurality of images includes obtaining images in a sequence where the focus position starts at one end of the range and incrementally steps through the range toward the other end of the range.

### Claim 3 (depends on 1)

The method of claim 1 wherein the focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the process continues until one of (i) the vision process has been successfully completed for at least one of the images and (ii) the vision process has been attempted for images at each of the different focus positions.

### Claim 4 (depends on 1)

The method of claim 1 wherein the focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the process continues until the vision process has been attempted for images at each of the different focus positions.

### Claim 5 (depends on 1)

The method of claim 1 wherein the step of obtaining a plurality of images further includes the step of selecting next focus positions as a function of data obtained from previously obtained images.

### Claim 6 (depends on 1)

The method of claim 1 further including the steps of using at least a subset of the images to determine one of (i) that the lens is focused on the symbol to be imaged, and (ii) that the lens is unfocused on the symbol to be imaged and, where the lens is focused on the symbol to be imaged, ending the process after attempting to perform the machine vision process on the image corresponding to the focused lens.

### Claim 7 (depends on 6)

The method of claim 6 further including the steps of, when the lens is unfocused on the symbol to be imaged, using at least one of the obtained images to determine how to better focus the lens on the symbol to be imaged and adjusting the lens to better focus on the symbol to be imaged prior to obtaining another image.

### Claim 8 (depends on 1)

The method of claim 1 wherein the image formation setting is at least one of light brightness, exposure duration and image sensor gain.

### Claim 9

A method for performing a vision process using a camera having a multi-focus lens having a lens field of view where the lens can be set at different focus positions the method comprising the steps of:
positioning at least one of the camera and an item to be imaged so the lens field of view is directed at the item to be imaged;
setting an image formation setting;
obtaining a subset of images at each of a plurality of different lens focus positions where the image formation setting is different for each of the images obtained at each lens focus position; and
after each image is obtained and while obtaining additional images, attempting to perform the vision process on the images.

### Claim 10

A method for facilitating a machine vision process using a camera having a multi-focus lens having a lens field of view, the method comprising the steps of:
a. positioning at least one of the camera and an item to be imaged so the lens field of view is directed at the item to be imaged;
b. setting an image formation setting;
c. obtaining an image of the item with the lens at the focus position and with the set image formation setting;
d. attempting to perform the machine vision process on the image;
e. while performing step (d), initiating steps (b) through (d) using a different image formation setting to obtain a next image of the item; and
f. after a subset of images have been obtained using different image formation settings at the focus position, while performing step (d), initiating steps (a) through (e) using a next focus position to obtain a next image of the item where the next focus position is different than any previous focus position.

### Claim 11 (depends on 10)

The method of claim 10 further including the step of repeating step (d) using the next image.

### Claim 12 (depends on 10)

The method of claim 10 further including the step of repeating steps (d) and (e) for a plurality of lens focus positions.

### Claim 13 (depends on 10)

The method of claim 10 wherein the machine vision process is one of a symbol reading process and a symbol locating process.

### Claim 14 (depends on 10)

The method of claim 10 further including the steps of, prior to initiating steps (b) and (c) using a next focus position, using at least one of the obtained images to determine how to better focus on the item to be imaged and selecting a next focus position to better focus on the item to be imaged.

### Claim 15

A system for performing a vision process using a camera having a multi-focus lens having a lens field of view where the lens can be set at different focus positions, the system comprising:
a processor programmed to perform the steps of:
setting an image formation setting;
controlling the camera to obtain a subset of images at each of a plurality of different lens focus positions where the image formation setting is different for each of the images obtained at each lens focus position; and
after each image is obtained and while obtaining additional images, attempting to perform the vision process on the images;
wherein the vision process includes one of locating a symbol in obtained images and decoding a symbol in obtained images.

### Claim 16 (depends on 15)

The system of claim 15 wherein the focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the processor is programmed to control the camera to obtain a plurality of images by obtaining images in a sequence where the focus position starts at one end of the range and incrementally steps through the range toward the maximum focus position.

### Claim 17 (depends on 15)

The system of claim 15 wherein the focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the processor attempts to perform the vision process until one of (i) the vision process has been successfully completed for at least one of the images and (ii) the vision process has been attempted for images at each of the different focus positions.

### Claim 18 (depends on 15)

The system of claim 15 wherein the processor is further programmed to perform the steps of using at least a subset of the images to determine one of (i) that the lens is focused on the symbol, and (ii) that the lens is unfocused on the symbol and, where the lens is focused on the symbol, ending the process after attempting to perform the machine vision process on the image corresponding to the focused lens.

### Claim 19 (depends on 18)

The system of claim 18 wherein the processor is further programmed to perform the steps of, when the lens is unfocused on the symbol, using at least one of the obtained images to determine how to better focus the lens on the symbol and adjusting the lens to better focus on the symbol to be imaged prior to obtaining another image.

### Claim 20 (depends on 15)

The system of claim 15 wherein the image formation setting is at least one of light brightness, exposure duration and image sensor gain.

### Claim 21

A system for performing a vision process using a camera having a multi-focus lens having a lens field of view where the lens can be set at different focus positions, the system comprising:
a processor programmed to perform the steps of:
setting an image formation setting;
obtaining a subset of images at each of a plurality of different lens focus positions where the image formation setting is different for each of the images obtained at each lens focus position; and
after each image is obtained and while obtaining additional images, attempting to perform the vision process on the images.

### Claim 22

A system for facilitating a machine vision process using a camera having a multi-focus lens having a lens field of view, the system comprising:
a processor programmed to perform the steps of:
a. setting the lens at a focus position;
b. setting an image formation setting;
c. obtaining an image of the item with the lens at the focus position and with the set image formation setting;
d. attempting to perform the machine vision process on the image;
e. while performing step (d), initiating steps (b) through (d) using a different image formation setting to obtain a next image of the item; and
f. after a subset of images have been obtained using different image formation settings at the focus position, while performing step (d), initiating steps (a) through (e) using a next focus position to obtain a next image of the item where the next focus position is different than any previous focus position.

### Claim 23 (depends on 22)

The system of claim 22 wherein the processor is further programmed to repeat step (f) for a plurality of lens focus positions.

### Claim 24 (depends on 22)

The system of claim 22 wherein the machine vision process is one of a symbol reading process and a symbol locating process.

### Claim 25

A method for obtaining a plurality of images using a camera having a multi-focus lens having a lens field of view where the lens has a range of focus positions between a maximum focus position and a minimum focus position, the method comprising the steps of:
positioning at least one of the camera and an item to be imaged so the lens field of view is directed at the item to be imaged;
setting the lens focus position at one of the maximum and minimum positions;
driving the lens focus position from the one of the maximum and minimum focus positions toward the other of the maximum and minimum focus positions; and
while driving the lens toward the other of the maximum and minimum focus positions, obtaining and storing a plurality of sequential images;
after the lens focus position is at the other of the maximum and minimum positions and the sequence of images has been stored prior to attempting to perform a machine vision process on any of the stored images, attempting to perform a machine vision process on each of the images until the process is successfully performed on at least one of the obtained images.

### Claim 26 (depends on 25)

The method of claim 25 further including the steps of obtaining images at the maximum and the minimum lens focus positions.

### Claim 27 (depends on 25)

The method of claim 25 wherein the step of attempting to perform a machine vision process includes, when the machine vision process is successfully performed on at least one of the images, halting further image acquisition.

### Claim 28 (depends on 27)

The method of claim 27 further including the step of, when the machine vision process is successfully performed on at least one of the images, indicating that the machine vision process has been successfully completed.

### Claim 29 (depends on 27)

The method of claim 27 wherein the machine vision process is one of locating a symbol in an image and decoding a symbol in an image.

### Claim 30

A system for obtaining a plurality of images using a camera having a multi-focus lens having a lens field of view where the lens has a range of focus positions between a maximum focus position and a minimum focus position, the method comprising the steps of:
with at least one of the camera and an item to be imaged positioned so the lens field of view is directed at the item to be imaged;
a processor programmed to perform the steps of:
setting the lens focus position at one of the maximum and minimum positions;
driving the lens focus position from the one of the maximum and minimum focus positions toward the other of the maximum and minimum focus positions;
while driving the lens toward the other of the maximum and minimum focus positions, obtaining and storing a plurality of sequential images; and
after the lens focus position is at the other of the maximum and minimum positions and the sequence of images has been stored prior to attempting to perform a machine vision process on any of the stored images, attempting to perform a machine vision process on each of the images until the process is successfully performed on at least one of the obtained images.

### Claim 31 (depends on 30)

The system of claim 30 wherein the processor is further programmed to perform the steps of obtaining images at the maximum and the minimum lens focus positions.

### Claim 32 (depends on 30)

The system of claim 30 wherein the step of attempting to perform a machine vision process includes, when the machine vision process is successfully performed on at least one of the images, halting further image acquisition.

### Claim 33 (depends on 32)

The system of claim 32 wherein the processor is further programmed to perform the steps of, when the machine vision process is successfully performed on at least one of the images, indicating that the machine vision process has been successfully completed.