Method for determining at least one head posture characteristic of a person wearing spectacles

Patent metadata

Field	Value
Publication number	US-9664929-B2
Application number	US-201314383746-A
Country	US
Kind code	B2
Filing date	Mar 8, 2013
Priority date	Mar 8, 2012
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

A method for determining at least one characteristic relating to the posture of the head ( 10 ) of a person ( 1 ) wearing spectacles ( 100 ) including a frame ( 110 ) and two lenses ( 150 G, 150 D), using a determining device including an image sensor, at least one light source and a computation unit, the method includes steps of: a) acquiring an image ( 301 ) of at least part of the wearer's head, in which the spectacles are illuminated by the light source; b) in the image, locating reflections ( 160 D, 160 G, 161 D, 161 G) from the light source, reflected by the two lenses of the spectacles; and c) deducing the wearer's head posture characteristic in relation to the image sensor, as a function of the position of the reflections in the image.

First claim

The invention claimed is:

1. A method for determining at least one postural characteristic of the head of a wearer of a pair of spectacles comprising a frame and two lenses, using a determining device comprising an image sensor, at least one light source and a processing unit, said determining method comprising steps of:
a) acquiring via the image sensor an image of at least part of the head of the wearer, in which image appears the pair of spectacles illuminated by the light source;
b) locating via the processing unit, in said image, largest reflections of the light source reflected by the optical faces of the two lenses of the pair of spectacles; and
c) deducing via the processing unit the postural characteristic of a position of the head of the wearer relative to said image sensor, as a function of the position of said largest reflections in said image.

2. The determining method as claimed in claim 1 , in which, in step b), the processing unit also locates in said image a point or an observable axis of the spectacle frame, and, in step c), the processing unit deduces the postural characteristic also as a function of the position of the point or the observable axis in said image.

3. The determining method as claimed in claim 2 , in which the observable axis is located, in step b), by determining the positions in said image of boxes circumscribed around the lenses or rims of the spectacle frame, and by locating the midline passing between the two circumscribed boxes.

4. The determining method as claimed in claim 3 , in which, the image sensor having an optical axis, said postural characteristic is an angle of orientation of the face of the wearer relative to the optical axis of the image sensor.

5. The determining method as claimed in claim 4 , in which said postural characteristic is a yaw angle, which separates the sagittal plane of the head of the wearer and the optical axis of the image sensor.

6. The determining method as claimed in claim 5 , in which, in step c), said yaw angle is calculated as a function of the distances separating the reflections from the observable axis.

7. The determining method as claimed in claim 1 , in which, in step a), the image sensor acquires said image in the infrared domain.

8. The determining method as claimed in claim 1 , in which, the determining device comprising a light source that is movable relative to said image sensor, provision is made, before step a), for a step of pre-positioning the light source, in which step the processing unit moves said light source so that the reflections of said light source reflected by the two lenses of the pair of spectacles are visible to the image sensor.

9. The determining method as claimed in claim 4 , wherein,
half pupillary distances of the wearer of a pair of spectacles are acquired by having the head of the wearer pivot about its longitudinal axis relative to said image sensor, the acquisition of the half pupillary distances of the wearer of a pair of spectacles including: i) a first operation of acquiring, via the image sensor, at least two separate images of at least one part of the head of the wearer, in which acquired images the pair of spectacles illuminated by the light source appear, and a yaw angle of the head of the wearer in each acquired image is determined from said postural characteristic, the yaw angle separating the sagittal plane of the head of the wearer and the optical axis of the image sensor;
ii) a second operation of locating, via the processing unit, in at least one of the images corneal reflections of the light source reflected by the two corneas of the wearer, and an axis of the pair of spectacles that is observable and central relative to the pair of spectacles;
iii) a third operation of measuring, via the processing unit, in each image processed in the second operation, pupillary distances between each of the corneal reflections and the observable axis; and
iv) a fourth operation of deducing the half pupillary distances as a function of the pupillary distances measured in the third operation.

10. The method as claimed in claim 9 , in which the yaw angle determined in each image acquired in the first operation is used:
to select a single image to be processed in operations ii) to iv), the yaw angle of which is substantially zero; or
to correct the pupillary distances measured in at least two images in order to deduce therefrom said half pupillary distances.

11. The method as claimed in claim 9 , in which said first operation comprises a step of selecting, from all of the acquired images, a small number of images in which the corneal reflections and the reflections reflected by the lenses are visible and do not overlap.

12. The method as claimed in claim 9 , further comprising an operation for determining a characteristic dimension of the spectacle frame, during which the pupillary distances or the half pupillary distances are scaled.

13. The method as claimed in claim 9 , in which the wearer stays still and the image sensor is moved to pivot about the longitudinal axis of the head of the wearer.

14. The determining method as claimed in claim 4 , wherein,
the behavior of the wearer of a pair of spectacles is detected
using the determining device with two targets, the detection of the behavior of the wearer of a pair of spectacles including:
i) a first operation of pre-positioning the wearer so that their gaze and their head are directed toward one of the two targets;
ii) a second operation of instructing the wearer to rapidly turn their gaze in the direction of the other of the two targets;
iii) a third operation of determining, from said postural characteristic, a yaw angle of the head of the wearer, the yaw angle separating the sagittal plane of the head of the wearer and the optical axis of the image sensor; and
iv) a fourth operation of deducing a coefficient quantifying the propensity of the wearer to turn their gaze by moving rather their head or their eyes, as a function of the determined yaw angle.

15. The determining method as claimed in claim 14 , further comprising, between the first and second operations, an operation for determining a first yaw angle of the head of the wearer wherein, in the fourth operation, said coefficient is also deduced as a function of said first yaw angle.

16. The determining method as claimed in claim 14 , in which, the second target comprising a light source, and the second operation includes turning on said light source.

17. The determining method as claimed in claim 1 , in which, in step b), the processing unit obtains horizontal orientation data and vertical orientation data of the lens relative to the light source that allow three-dimensional information regarding the posture of the wearer to be deduced therefrom, where moving the light source relative to the lens necessarily modifies the positions of the reflections on the optical faces of the two lenses.

18. A device for determining at least one postural characteristic of the head of a wearer of a pair of spectacles comprising a frame and two lenses, which comprises:
at least one light source positioned for illuminating the head of the wearer, wherein in use the at least one light source illuminates the head of the wearer;
an image sensor positioned for acquiring an image of at least one part of the head of the wearer, in which image the pair of spectacles illuminated by the light source appears, wherein in use the image sensor acquires the image of at least one part of the head of the wearer; and
a processing unit connected to the image sensor to

Assignees

• Essilor Int

Inventors

• Haddadi Ahmed
• Delzers Jean

Classifications

• A61B3/11

  for measuring interpupillary distance or diameter of pupils · CPC title

• A61B5/1128

  using image analysis (A61B5/1127 takes precedence) · CPC title

• A61B3/14

  Arrangements specially adapted for eye photography · CPC title

• G02C13/003 Primary

  Measuring during assembly or fitting of spectacles · CPC title

• A61B3/111

  for measuring interpupillary distance · CPC title