# US 12,604,098 B2 · Device and method for exposure correction using a low-resolution brightness map > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,604,098 B2 - Document ID: US12604098B2 - Status: Granted - Kind: B2 - Application number: 18/645,558 - Filed: 2024-04-25 - Published: 2025-10-30 - Granted: 2026-04-14 - Earliest claimed: 2024-04-25 - Assignees: Varjo Technologies Oy - Applicants: Varjo Technologies Oy - Inventors: Mikko Ollila; Ville Timonen - Web page: https://patentgrep.com/patent/US12604098B2 ## CPC - H04N 23/73: by influencing the exposure time - G06F 3/013: {Eye tracking input arrangements (G06F3/015 takes precedence)} - G06V 10/25: Determination of region of interest [ROI] or a volume of interest [VOI] - G06V 10/60: relating to illumination properties, e.g. using a reflectance or lighting model - G06V 10/82: using neural networks - H04N 23/76: by influencing the image signals - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING ## Abstract Disclosed is method for exposure correction. The method includes receiving at least one image; defining a low-resolution brightness map, associated with the at least one image, corresponding to an ambient lighting condition in which the at least one image is captured; and correcting an exposure in the at least one image, to restore at least one inaccurately-illuminated area of the at least one image, by guiding the at least one image based on the low-resolution brightness map, wherein the at least one inaccurately-illuminated area is at least one of: at least one under-illuminated area of the at least one image, at least one over-illuminated area of the at least one image. ## Claims ### Claim 1 A method for exposure correction, the method comprising: receiving at least one image; defining a low-resolution brightness map, associated with the at least one image, corresponding to an ambient lighting condition in which the at least one image is captured; and correcting an exposure in the at least one image, to restore at least one inaccurately-illuminated area of the at least one image, by guiding the at least one image based on the low-resolution brightness map, wherein the at least one inaccurately-illuminated area is at least one of: at least one under-illuminated area of the at least one image, at least one over-illuminated area of the at least one image; wherein the low-resolution brightness map is defined as a matrix of target brightness values, one for each pixel in the at least one image, and wherein a given target brightness value corresponding to each pixel is one of: an average-brightness value determined using brightness values of all pixels in any one of: the at least one image, at least one previously-captured image, a brightness value determined based on an exposure level corresponding to each pixel in any one of: the at least one image, at least one previously-captured image. ### Claim 2 (depends on 1) The method according to claim 1, wherein the at least one inaccurately-illuminated area of the at least one image comprises one of: a region of interest in the at least one image, a peripheral region in the at least one image, wherein the peripheral region surrounds the region of interest. ### Claim 3 (depends on 2) The method according to claim 2, further comprising identifying the region of interest and the peripheral region, based on a gaze direction of a user. ### Claim 4 (depends on 2) The method according to claim 2, further comprising dynamically correcting an exposure of the region of interest in the at least one image. ### Claim 5 (depends on 1) The method according to claim 1, further comprising one of: obtaining ambient light data, corresponding to the ambient lighting condition in which the at least one image is captured, for defining the low-resolution brightness map, generating ambient light data, by using pre-determined data corresponding to the ambient lighting condition in which the at least one image is captured, for defining the low-resolution brightness map. ### Claim 6 A method for exposure correction, the method comprising: receiving at least one image; defining a low-resolution brightness map, associated with the at least one image, corresponding to an ambient lighting condition in which the at least one image is captured; and correcting an exposure in the at least one image, to restore at least one inaccurately-illuminated area of the at least one image, by guiding the at least one image based on the low-resolution brightness map, wherein the at least one inaccurately-illuminated area is at least one of: at least one under-illuminated area of the at least one image, at least one over-illuminated area of the at least one image; wherein the step of guiding the at least one image based on the low-resolution brightness map is performed using at least one neural network, wherein an input of the at least one neural network comprises the at least one image and the low-resolution brightness map, and an output of the at least one neural network comprises at least one corrected image having at least one correctly-illuminated area, and wherein the at least one neural network is continuously trained to identify and correct the at least one inaccurately-illuminated area of the at least one image. ### Claim 7 A head-mounted display device comprising: at least one camera for capturing at least one image; and a processor operatively coupled to the at least one camera, wherein the processor is configured to: receive the at least one image; define a low-resolution brightness map, associated with the at least one image, corresponding to an ambient lighting condition in which the at least one image is captured; and correct an exposure in the at least one image, to restore at least one inaccurately-illuminated area of the at least one image, by guiding the at least one image based on the low-resolution brightness map, wherein the at least one inaccurately-illuminated area is at least one of: at least one under-illuminated area of the at least one image, at least one over-illuminated area of the at least one image; wherein the low-resolution brightness map is defined as a matrix of target brightness values, one for each pixel in the at least one image, and wherein the processor is further configured to determine a given target brightness value corresponding to each pixel as one of: an average-brightness value that is determined using the brightness values of all pixels in any one of: the at least one image, at least one previously-captured image, a brightness value that is determined based on an exposure level corresponding to each pixel in any one of: the at least one image, at least one previously-captured image. ### Claim 8 (depends on 7) The head-mounted display device according to claim 7, wherein the at least one inaccurately-illuminated area of the at least one image comprises one of: a region of interest the at least one image, a peripheral region in the at least one image, wherein the peripheral region surrounds the region of interest. ### Claim 9 (depends on 8) The head-mounted display device according to claim 8, further comprising gaze-tracking means operatively coupled to the processor, wherein the processor is further configured to: obtain, from the gaze-tracking means, information indicative of a gaze direction of a user; and identify the region of interest and the peripheral region, based on the gaze direction. ### Claim 10 (depends on 8) The head-mounted display device according to claim 8, wherein the processor is further configured to dynamically correct an exposure of the region of interest in the at least one image. ### Claim 11 (depends on 7) The head-mounted display device according to claim 7, further comprising an ambient light sensor, operatively coupled to the processor, for acquiring ambient light data corresponding to the ambient lighting condition in which the image is captured. ### Claim 12 (depends on 7) The head-mounted display device according to claim 7, wherein the processor is further configured to generate ambient light data, by using pre-determined data corresponding to the ambient lighting condition in which the image is captured. ### Claim 13 A head-mounted display device comprising: at least one camera for capturing at least one image; and a processor operatively coupled to the at least one camera, wherein the processor is configured to: receive the at least one image; define a low-resolution brightness map, associated with the at least one image, corresponding to an ambient lighting condition in which the at least one image is captured; and correct an exposure in the at least one image, to restore at least one inaccurately-illuminated area of the at least one image, by guiding the at least one image based on the low-resolution brightness map, wherein the at least one inaccurately-illuminated area is at least one of: at least one under-illuminated area of the at least one image, at least one over-illuminated area of the at least one image; wherein when fusing the at least one image and the low-resolution brightness map, the processor is configured to use at least one neural network, wherein an input of the at least one neural network comprises the at least one image and the low-resolution brightness map, and an output of the at least one neural network comprises at least one corrected image having at least one correctly-illuminated area, and wherein the at least one neural network is continuously trained to identify and correct the at least one inaccurately-illuminated area of the at least one image.