| 主权项 |
1. An image capturing method of capturing an image of a subject while emitting light from two light-emitting sources toward the subject, the light-emitting sources being configured so that color temperatures of light emitted from the respective light-emitting sources are different from each other and a ratio between the volumes of light emitted from the light-emitting sources is variably controllable, the method comprising:
a light-source color obtaining step of obtaining a light-source color of ambient light; a preliminary image capturing step including a no-light-emission image capturing step of capturing an image of the subject without light emission from the two light-emitting sources, and a light-emission image capturing step of capturing an image of the subject with light emitted from the two light-emitting sources; a light-emitting source light volume obtaining step of obtaining light volume information indicating a relationship between the light volume related to ambient light and the total volume of light from the two light-emitting sources, on the basis of the images of the subject captured in the preliminary image capturing step; an image capturing step of capturing an image of the subject while emitting light from the two light-emitting sources toward the subject in such a manner that volumes of light emitted from the two light-emitting sources respectively correspond to those represented by a predetermined point which is (i) an intersection point of a first line and a line segment or (ii) a point close to the intersection point in xy chromaticity coordinates, on the basis of the intersection point and the light volume information obtained in the light-emitting source light volume obtaining step, the first line passing through a first coordinate point in the xy chromaticity coordinates which represents the light-source color obtained in the light-source color obtaining step, the first line being drawn so as to cross the line segment at a predetermined angle, the line segment connecting two coordinate points in the xy chromaticity coordinates which points respectively represent colors of light emitted from the respective two light-emitting sources; and a White Balance adjustment step of performing White Balance adjustment on the image captured in the image capturing step on a basis of a White Balance adjustment correction value obtained with reference to a second coordinate point which is on a second line and corresponds to the light volume information obtained in the light-emitting source light volume obtaining step, the second line passing through the predetermined point and the first coordinate point in the xy chromaticity coordinates which represents to the light-source color, wherein when: a color component ratio of R, G, and B signals which are obtained from the image captured in the no-light-emission image capturing step and normalized with respect to G signal is defined as P0_r, P0_g, P0_b; a color component ratio of a difference between (i) R, G, and B signals obtained from the image captured in the light-emission image capturing step and (ii) R, G, and B signals obtained from the image captured in the no-light-emission image capturing step, values of which differences are normalized with respect to G signal, is defined as P1_r, P1_g, P1_b; and a color component ratio of R, G, and B components of a mixed color of combined light emitted from the two light-emitting sources normalized with respect to G component is defined as P2_r, P2_g, P2_b, a color component ratio Pe_r, Pe_g, Pe_b of R, G, and B components of the light-source color of ambient light normalized with respect to G component is calculated on the basis of an equation in which: Pe_i=P0_i*P2_i/P1_i, where i designates each of r, q and b: i=r, i=g, and i=b. |
