# US 2021/0344827 A1 · Method and system for estimating exposure time of a multispectral light source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0344827 A1 - Document ID: US20210344827A1 - Status: Published application - Kind: A1 - Application number: 17/282,391 - Filed: 2019-10-04 - Published: 2021-11-04 - Earliest claimed: 2018-10-04 - Assignees: Barco N.V. - Applicants: Barco N.V. - Inventors: Gert VAN HOEY; Bart DIRICX - Web page: https://patentgrep.com/patent/US20210344827A1 ## CPC - G03B 15/02: Illuminating scene - H04N 23/73: by influencing the exposure time - H04N 23/10: for generating image signals from different wavelengths - H04N 23/56: provided with illuminating means - H04N 23/74: by influencing the scene brightness using illuminating means - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Methods and/or systems and/or controllers for estimating an exposure time for an imaging device, especially for estimating exposure times that provide maximum saturation levels while keeping the image sensor operating within its linear range. The imaging device includes an external or embedded image sensor and an external or embedded light source. Such a device may be a dermatoscope, a laparoscope, an endoscope, a microscope, or any digital media devices such as mobile phones, tablets, laptops etc. The methods and/or systems and/or controllers can include an LED or OLED light source or any type of solid-state light source. ## Claims ### Claim at position 1 1-21. (canceled) ### Claim 22 A method for estimating an exposure parameter value for imaging an object with an imaging device comprising a plurality of solid state light sources arranged into at least one first group and at least one second group, the first and second light source groups emitting light within wavelength bands wherein the total coverage of all wavelength bands of a first light source group is at least as wide or wider as any wavelength band of a second light source group, an image sensor having digital sensor values adopting a level of saturation, an image processor receiving the digital sensor values and carrying out the method; the method comprising the steps of: imaging the object with the at least one first light source group with a first exposure parameter value, the image sensor capturing an image of the object, and mapping the image onto the digital sensor values, and the image processor estimating a second exposure parameter value for the at least one second light source group from the digital sensor values, and extracting at least one percentile of the digital sensor values, and estimating the second exposure parameter value as a function of the first exposure parameter value and of a constant, and of device calibration data, and of a target level of saturation of the image sensor, and of a first black level, and of the measured digital sensor values of that least one first light source group, and of a second black level, wherein the device calibration data comprises the relationship between the digital sensor values and the sensor exposure parameter value for a reference object. ### Claim 23 (depends on 22) The method according to claim 22, comprising extracting percentiles in a range selected from 50 to 100, 70 to 100, 95 to 98 or any of 75, 85, 95, 98, 99, 99.5, 100% percentiles. ### Claim 24 (depends on 22) The method according to claim 22, comprising estimating the exposure parameter value by using a multiple of percentiles. ### Claim 25 (depends on 22) The method according to claim 22, comprising including in the calibration data one or more of: sensor black offset, sensor optical sensitivity, sensor non-linearity, sensor non-uniformity, light source drive current, sensor exposure time, sensor analog gain, sensor digital gain, light source optical efficiency, light source non-uniformity or light source temperature. ### Claim 26 (depends on 22) The method according to claim 22, comprising estimating the exposure parameter value by using at least two first light source groups. ### Claim 27 (depends on 22) The method according to claim 22, comprising estimating the exposure parameter value by estimating any of: light source current, sensor exposure time, sensor analog gain, sensor digital gain, light source brightness, optical aperture. ### Claim 28 (depends on 23) The method according to claim 23, wherein for each second light source group the constant is the 95-98 percentile level of saturation of a first light source group minus the first black level divided by the corresponding exposure parameter value of the first light source group, divided by a percentile selected from a 95-98 percentile level of saturation or any of a 75, 85, 95, 98, 99, 99.5, 100% percentile of the second light source group minus the second black level divided by the corresponding exposure parameter value for the second light source group. ### Claim 29 (depends on 22) The method according to claim 22, wherein the image sensor has an off-set current and the levels of saturation are decreased with a value corresponding to the off-set current. ### Claim 30 (depends on 22) The method according to claim 22, wherein the predetermined level of saturation is the highest linear level of saturation of the image sensor. ### Claim 31 A system for estimating an exposure parameter value for imaging an object with an imaging device comprising: a plurality of solid state light sources arranged into at least a first light source group and at least a second light source group, the light source groups emitting light within wavelength bands wherein the total coverage of all wavelength bands of the first light source group is at least as wide or wider as any wavelength band of the second light source group, an image sensor having digital sensor values adopting a level of saturation, an image processor receiving the digital sensor values and the system is configured to implement the steps of: imaging the object with at least the first light source group with a first exposure parameter value, the image sensor capturing an image of the object, and mapping the image onto the digital sensor values, and the image processor estimating a second exposure parameter value for at least the second light source group from the digital sensor values, and extracting at least one percentile of the digital sensor values, and estimating the second exposure parameter value as a function of the first exposure parameter value and of a constant and of device calibration data, and of a target level of saturation of the image sensor, and of a first black level, and of the measured digital sensor values of at least the first light source group, and of a second black level, wherein the device calibration data comprises the relationship between the digital sensor values and the sensor exposure parameter value for a reference object. ### Claim 32 (depends on 31) The system according to claim 31, adapted to estimate the exposure parameter value by using a multiple of percentiles. ### Claim 33 (depends on 31) The system according to claim 31, wherein the calibration data includes one or more of: sensor black offset, sensor optical sensitivity, sensor non-linearity, sensor non-uniformity, light source drive current, sensor exposure time, sensor analog gain, sensor digital gain, light source optical efficiency, light source non-uniformity or light source temperature. ### Claim 34 (depends on 31) The system according to claim 31, adapted to estimate the exposure parameter value by using at least two first light source groups. ### Claim 35 (depends on 31) The system according to claim 31, adapted to estimate the exposure parameter value by estimating any of: light source current, sensor exposure time, sensor analog gain, sensor digital gain, light source brightness, optical aperture. ### Claim 36 (depends on 31) The system according to claim 31, wherein for each second light source group the constant is the 95-98 percentile level of saturation of a first light source group divided by the corresponding exposure parameter value of the first light source group minus the first black level divided by a percentile selected from a 95-98 percentile level of saturation or any of a 75, 85, 95, 98, 99, 99.5, 100% percentile of the second light source group minus the second black level divided by the corresponding exposure parameter value for the second light source group. ### Claim 37 (depends on 31) The system according to claim 31, wherein the image sensor has an off-set current and the levels of saturation are decreased with a value corresponding to the off-set current. ### Claim 38 (depends on 31) The system according to claim 31, wherein the predetermined level of saturation is the highest linear level of saturation of the image sensor. ### Claim 39 A controller for estimating an exposure parameter value for imaging an object with an imaging device, said imaging device comprising: a plurality of solid state light sources arranged into at least one first group and at least one second group, the first and second light source groups emitting light within wavelength bands wherein the total coverage of all wavelength bands of a first light source group is at least as wide or wider as any wavelength band of a second light source group, and an image sensor having digital sensor values adopting a level of saturation, the controller comprising: an image processor receiving the digital sensor values and being adapted to carry out the steps of: imaging the object with the at least one first light source group with a first exposure parameter value, the image sensor capturing an image of the object, and mapping the image onto the digital sensor values, and the image processor estimating a second exposure parameter value for the at least one second light source group from the digital sensor values, and extracting at least one percentile of the digital sensor values, and estimating the second exposure parameter value as a function of the first exposure parameter value and of a constant, and of device calibration data, and of a target level of saturation of the image sensor, and of a first black level, and of the measured digital sensor values of that least one first light source group, and of a second black level, wherein the device calibration data comprises the relationship between the digital sensor values and the sensor exposure parameter value for a reference object. ### Claim 40 (depends on 39) The controller according to claim 39, for use with a reference target, wherein for each of the second light source groups the constant is selected from the 95-98 percentile or any of a 75, 85, 95, 98, 99, 99.5, 100% percentile level of saturation of the first light source group minus the first black level divided by the corresponding exposure parameter value of the first light source group, divided by a percentile selected from the 95-98 percentile level of saturation or any of the 75, 85, 95, 98, 99, 99.5, 100% percentile of the second light source group minus the second black level divided by the corresponding exposure parameter value for the second light source group. ### Claim 41 (depends on 22) A computer program product stored on a machine readable non-transient storage means, the program product comprising code which, when executed on a processing device, carries out a method of claim 22.