# US 10,873,707 B2 · Image pickup apparatus and method, for ensuring correct color temperature based on first or second preliminary light emission of a flash device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,707 B2 - Document ID: US10873707B2 - Status: Granted - Kind: B2 - Application number: 16/050,254 - Filed: 2018-07-31 - Published: 2019-02-07 - Granted: 2020-12-22 - Earliest claimed: 2017-08-04 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Toshifumi Osawa - Web page: https://patentgrep.com/patent/US10873707B2 ## CPC - H04N 23/74: by influencing the scene brightness using illuminating means - G03B 7/16: in accordance with both the intensity of the flash source and the distance of the flash source from the object, e.g. in accordance with the "guide number" of the flash bulb and the focusing of the camera - H04N 23/12: with one sensor only - H04N 23/71: Circuitry for evaluating the brightness variation - H04N 23/73: by influencing the exposure time - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - 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) ## Abstract An image pickup apparatus capable of ensuring the accuracy of a proper main light emission amount. A flash device can change an emission color temperature by changing a ratio of light emission between light sources different in emission color temperature. A photometry unit measures a luminance of light reflected from an object by preliminary light emission of the flash device. It is selected whether to perform second preliminary light emission at a color temperature changed according to at least one of spectral characteristics information of the light source, shooting condition information, and photometric value information obtained by first preliminary light emission, and determine a main light emission amount based on a photometric result obtained by second preliminary light emission, or to determine the main light emission amount based on a photometric result obtained by first preliminary light emission without performing second preliminary light emission. ## Claims ### Claim 1 An image pickup apparatus comprising: a photometry sensor; a memory storing instructions; and at least one processor that implements the instructions to execute a plurality of tasks, including: a photometry task that measures, using the photometry sensor, a luminance of light reflected from an object at the time of preliminary light emission of a flash device that is configurable to change an emission color temperature by changing a ratio of light emission between a plurality of light sources different in emission color temperatures; and a selection task that, upon main light emission being performed at an emission color temperature different from a predetermined emission color temperature of first preliminary light emission: selects whether to perform second preliminary light emission, after the first preliminary light emission is performed, at an emission color temperature changed according to at least one of spectral characteristics information of the light source, shooting condition information, or photometric value information obtained at the time of the first preliminary light emission; and determine a main light emission amount based on a photometric result obtained by the photometry task at the time of the first or second preliminary light emission. ### Claim 2 (depends on 1) The image pickup apparatus according to claim 1, wherein the plurality of tasks include a determination task that determines whether or not to change the emission color temperature at the time of the main light emission according to a result of calculation of the main light emission amount based on the photometric result obtained at the time of the first preliminary light emission. ### Claim 3 (depends on 2) The image pickup apparatus according to claim 2, wherein, in a case where the main light emission amount calculated based on the photometric result obtained at the time of the first preliminary light emission is not within a predetermined amount, the determination task determines that the emission color temperature at the time of the main light emission is to be changed. ### Claim 4 (depends on 1) The image pickup apparatus according to claim 1, wherein in a case where correction calculation of the main light emission amount is determined to be possible using the photometry information obtained at the time of the first preliminary light emission, based on spectral characteristics information of the light source, the selection task determines the main light emission amount based on the photometric result obtained at the time of the first preliminary light emission without performing the second preliminary light emission. ### Claim 5 (depends on 4) The image pickup apparatus according to claim 4, wherein in a case where the spectral characteristics of the light source have continuity, and do not include an emission line-like component, the selection task determines that the correction calculation of the main light emission amount is possible using the photometry information obtained at the time of the first preliminary light emission, based on the spectral characteristics information of the light source. ### Claim 6 (depends on 1) The image pickup apparatus according to claim 1, wherein in a case where calculation of the main light emission amount is determined to be possible using the photometry information obtained at the time of the first preliminary light emission, based on the spectral characteristics information of the light source, the selection task selects to perform the second preliminary light emission and determines the main light emission amount based on the photometric result obtained by the photometry task at the time of the second preliminary light emission. ### Claim 7 (depends on 1) The image pickup apparatus according to claim 1, wherein in a case where the shooting condition is determined to correspond to one of bounce shooting, high-magnification shooting at a magnification not smaller than a predetermined magnification or long-distance shooting at a distance not shorter than a predetermined distance, or a shooting condition having an amount of environmental light, which is not smaller than a predetermined amount, the selection task selects to perform the second preliminary light emission, and determines the main light emission amount based on the photometric result obtained by the photometry task at the time of the second preliminary light emission. ### Claim 8 (depends on 1) The image pickup apparatus according to claim 1, wherein in a case where a photometric value obtained at the time of the first preliminary light emission is smaller than a predetermined value or close to a saturation level, the selection task selects to perform the second preliminary light emission, and determines the main light emission amount based on the photometric result obtained by the photometry task at the time of the second preliminary light emission. ### Claim 9 A method of controlling an image pickup apparatus using a flash device that is configurable to change an emission color temperature by changing a ratio of light emission between a plurality of light sources different in emission color temperatures, and a photometry sensor, the method comprising: measuring, using the photometry sensor, a luminance of light reflected from an object at the time of preliminary light emission of the flash device; and upon main light emission being performed at an emission color temperature different from a predetermined emission color temperature of first preliminary light emission; selecting whether to perform second preliminary light emission, after the first preliminary light emission is performed, at an emission color temperature changed according to at least one of spectral characteristics information of the light source, shooting condition information, or photometric value information obtained at the time of the first preliminary light emission; and determining a main light emission amount based on a photometric result obtained by the measuring at the time of the first or second preliminary light emission.