Dynamic optimization of light source power

Patent metadata

Field	Value
Publication number	US-2016227113-A1
Application number	US-201314129784-A
Country	US
Kind code	A1
Filing date	Oct 25, 2013
Priority date	Oct 25, 2013
Publication date	Aug 4, 2016
Grant date	—

Abstract

Technologies for power optimization of light sources include an imaging device to generate a captured image of a subject. The imaging device analyzes the captured image to determine, in the captured image, a location of the subject's eye relative to the imaging device, an iris-pupil contrast of the subject's eye, and a glint intensity of glints present on the subject's eye. The imaging device determines, for each of a plurality of light sources, an illumination efficiency based on a distance between the camera and the subject's eye, a distance between the light source and the subject's eye, an incidence angle of the light source relative to the subject's eye, and a power profile of the light source. The imaging device determines an amount of power to supply to each light source to reduce a total cumulative power supplied to the light sources based on one or more power constraints.

First claim

1 - 25 . (canceled)

26 . An imaging device for power optimization of light sources of the imaging device, the imaging device comprising:
a camera to generate a captured image of a subject; an image analysis module to analyze the captured image to (i) determine a location of an eye of the subject in the captured image relative to the imaging device, (ii) determine an iris-pupil contrast between the iris and the pupil of the subject's eye in the captured image, and (iii) determine a glint intensity of one or more glints present on the subject's eye in the captured image; an illumination efficiency determination module to determine, for each light source of a plurality of light sources of the imaging device, an illumination efficiency based on (i) a distance between the camera and the subject's eye, (ii) a distance between the corresponding light source and the subject's eye, (iii) an incidence angle of the corresponding light source relative to the subject's eye, and (iv) a power profile of the corresponding light source; and a power optimization module to determine an amount of power to supply to each light source to reduce a total cumulative power supplied to the plurality of light sources based on one or more power constraints, wherein each of the power constraints is based on at least one of the iris-pupil contrast, the glint intensity, or the illumination efficiency of one or more of the plurality of light sources.

27 . The imaging device of claim 26 , wherein to determine the location of the subject's eye relative to the imaging device comprises to determine the three-dimensional location of the subject's eye relative to the imaging device based on the one or more glints present on the subject's eye.

28 . The imaging device of claim 26 , wherein to determine the iris-pupil contrast comprises to compare the intensity of an iris region of the subject's eye in the captured image to a pupil region of the subject's eye in the captured image.

29 . The imaging device of claim 28 , wherein the iris-pupil contrast is the difference between (i) an average intensity of pixels of the captured image corresponding to the iris region and (ii) an average intensity of pixels of the captured image corresponding to the pupil region.

30 . The imaging device of claim 26 , wherein to determine the glint intensity comprises to (i) identify a glint region corresponding with a glint of the one or more glints present on the subject's eye and (ii) determine the maximum intensity of pixels of the captured image corresponding to the glint region,
wherein the glint intensity is the maximum intensity of the glint region.

31 . The imaging device of claim 26 , wherein to determine the illumination efficiency comprises to determine the distance between the camera and the subject's eye and the distance between the corresponding light source and the subject's eye based on the determined location of the subject's eye relative to the imaging device.

32 . The imaging device of claim 26 , wherein the illumination efficiency determination module is to determine the illumination efficiency based on the expression,

C
·

L


(
θ
)

D
EL
2



D
EC
2

,

wherein C is a scalar coefficient related to the camera, θ is the incidence angle of the corresponding light source, L( ) is a normalized power profile of the power profile of the corresponding light source and is dependent on the incidence angle of the corresponding light source, D EL is the distance between the corresponding light source and the subject's eye, and D EC is the distance between the camera and the subject's eye.

33 . The imaging device of claim 26 , wherein to reduce the total cumulative power supplied to the light sources comprises to maintain the power supplied to each light source inclusively between zero and a maximum operating power of the corresponding light source.

34 . The imaging device of claim 26 , wherein to reduce the total cumulative power supplied to the light sources based on one or more power constraints comprises to maintain the iris-pupil contrast at a contrast value not less than a predefined contrast value.

35 . The imaging device of claim 34 , wherein to maintain the iris-pupil contrast at a contrast value not less than the predefined contrast value comprises to maintain an inequality,

∑
i



T
i

·

E
i

·

P
i

≥

IPC
0

,

wherein i is an index of the corresponding light source, T i is an activation time of the corresponding light source, E i is the illumination efficiency of the corresponding light source, P i is the power supplied to the corresponding light source, and IPC 0 is the predefined contrast value.

36 . The imaging device of claim 26 , wherein to reduce the total cumulative power of light sources based on one or more power constraints comprises to maintain, for each glint of the one or more glints present on the subject's eye, a glint-eye contrast of the corresponding glint from a corresponding light source at a contrast value not less than a predefined ratio of a sum of intensity of the other light sources.

37 . The imaging device of claim 36 , wherein to maintain the glint-eye contrast of the corresponding glint from the corresponding light source at a contrast value not less than the predefined ratio of the sum of intensity of the other light sources comprises to maintain an inequality,

SR
·

T
i

·

E
i

·

P
i

≥

DR
·

∑
j



(

T
j

·

E

Assignees

• Intel Corp

Inventors

• Horesh Nizan

Classifications

• G03B15/03 Primary

  Combinations of cameras with lighting apparatus; Flash units · CPC title

• H04N23/65

  Control of camera operation in relation to power supply · CPC title

• H04N23/611

  where the recognised objects include parts of the human body · CPC title

• H04N23/74

  by influencing the scene brightness using illuminating means · CPC title

• H04N23/61

  based on recognised objects · CPC title