Image capturing apparatus, image capturing method, and computer program
AssigneeCanon Kabushiki Kaisha
InventorTatsuyuki Tokunaga
Life of this patent
Estimating the term…
Abstract
An image capturing apparatus in which the ratio between the brightness just before preliminary light emission and the brightness at preliminary light emission is calculated for each of a plurality of photometric areas. The highest ratio among the ratios in the areas is extracted as a reference value, the extracted reference value is compared with the ratio in each area, and a weighting coefficient in each area is calculated. By using the obtained weighting coefficient, the amount of light to be emitted for obtaining correct exposure is calculated.
Claims19
An image capturing apparatus comprising:
- a preliminary-emission control unit configured to perform preliminary light emission to a subject;
- a photometric unit configured to measure brightness of the subject in a picture frame having a plurality of areas at a first timing when the preliminary-emission control unit is not performing preliminary light emission and at a second timing when the preliminary-emission control unit is performing preliminary light emission;
- a calculating unit calculating a ratio between first photometric information indicating the brightness measured by the photometric unit at the first timing and second photometric information indicating the brightness measured by the photometric unit at the second timing, the calculating unit calculating the ratio for each of the plurality of areas;
- an extracting unit extracting a reference ratio from among the ratios of the plurality of areas calculated by the calculating unit;
- an evaluation-value calculating unit comparing the reference ratio extracted by the extracting unit with the ratios of the plurality of areas calculated by the calculating unit, and calculating an evaluation value for each of the plurality of areas based on the comparison;
- and
- an actual-emission-light calculating unit evaluating the second photometric information for each area based on the evaluation value of each area calculated by the evaluation-value calculating unit, and calculating an amount of light to be emitted in an exposure operation based on the evaluation.
A method for controlling an amount of light emitted from a strobe device for taking a picture of a subject with an image capturing apparatus, the method comprising the following steps:
- a preliminary-emission control step of performing preliminary light emission to the subject;
- a measuring step of measuring brightness of the subject in a picture frame having a plurality of areas at a first timing when preliminary light emission is not performed in the preliminary-emission control step and at a second timing when preliminary light emission is being performed in the preliminary-emission control step;
- a calculating step of calculating a ratio between first photometric information indicating the brightness measured at the first timing in the measuring step and second photometric information indicating the brightness measured at the second timing in the measuring step, the ratio being calculated for each of the plurality of areas;
- an extracting step of extracting a reference ratio from among the ratios for the plurality of areas calculated in the calculating step;
- an evaluation-value calculating step of comparing the reference ratio extracted in the extracting step with the ratio for each area calculated in the calculating step and calculating an evaluation value for each area based on the comparison;
- and
- an actual-emission-light calculating step of evaluating the second photometric information for each area by using the evaluation value for each area calculated in the evaluation-value calculating step and calculating an amount of light to be emitted in an exposure operation based on the evaluation.
Dependencies are inferred from the claim text.