US 11,871,117 B2
System for performing ambient light image correction
Erik Gosuinus Petrus Schuijers, Breda (NL); Jonathan Alambra Palero, Waalre (NL); and Yannyk Parulian Julian Bourquin, Eindhoven (NL)
Assigned to KONINKLIJKE PHILIPS N.V., Eindhoven (NL)
Appl. No. 17/782,277
Filed by KONINKLIJKE PHILIPS N.V., Eindhoven (NL)
PCT Filed Dec. 15, 2020, PCT No. PCT/EP2020/086198
§ 371(c)(1), (2) Date Jun. 3, 2022,
PCT Pub. No. WO2021/122582, PCT Pub. Date Jun. 24, 2021.
Claims priority of application No. 19218759 (EP), filed on Dec. 20, 2019.
Prior Publication US 2023/0016923 A1, Jan. 19, 2023
Int. Cl. H04N 23/72 (2023.01)
CPC H04N 23/72 (2023.01) 20 Claims
OG exemplary drawing
 
1. A system for performing ambient light image correction, the system comprising:
a light source configured to provide pulsed illumination to a subject;
an imaging unit configured to capture, while the subject is illuminated by the pulsed illumination provided by the light source, a plurality of images of the subject, wherein each image of the plurality of images is captured at an exposure time shorter than a wave period of the pulsed illumination, wherein a pulse frequency of the pulsed illumination provided by the light source is not a multiple integral of a frame rate at which the plurality of images are captured by the imaging unit, and wherein a total time during which the plurality of images are captured is at least half of the wave period of the pulsed illumination; and
a control unit configured to:
obtain a predetermined number n of a plurality of captured images, wherein the plurality of candidate images are n sequential images of the plurality of images;
generate, for each pixel location of every pixel location in the plurality of candidate images, a respective sorted list of pixels by sorting respective pixels each corresponding to the respective pixel location in the plurality of candidate images, wherein the sorting is based on a pixel value of the respective pixels;
apply, for the each pixel location of every pixel location in the plurality of candidate images, a set of weights to the respective sorted list of pixels to obtain a plurality of weighted and sorted lists of pixels, wherein the set of weights is associated with a least squares approximation of a probability density function of the pixel value over time; and
generate an estimated ambient light corrected image based on the plurality of weighted and sorted lists of pixels by summing the plurality of weighted and sorted lists of pixels.