Digital camera and method for controlling emission amount of flash

A method for controlling emission amount of a flash of a digital camera, the method comprising the steps of:

• providing, as components of the digital camera:
• an imaging unit for generating image data representing a subject;
• a flash device for emitting a flash;
• and a face region extraction unit for detecting a face included in the image data generated by the imaging unit and outputting region information that indicates a region corresponding to the face;
• obtaining the region information outputted from the face region extraction unit;
• causing the flash device to emit a preliminary flash emission to obtain image data representing the subject during the preliminary flash emission;
• obtaining image data representing the subject during non-flash emission immediately preceding or after the preliminary flash emission;
• performing a calculation on the image data obtained during the preliminary flash emission and on the image data obtained during the non-flash emission, without using the region information to obtain a provisional adequate value Cn for the emission amount;
• performing a calculation on the image data obtained during the preliminary flash emission and on the image data obtained during the non-flash emission, using the region information to obtain a provisional adequate value Cf for the emission amount;
• performing an adjustment using the provisional adequate value Cn and the provisional adequate value Cf to determine an adequate emission amount Ch of the flash;
• storing a variable parameter that indicates an influence of the provisional adequate value Cf in the adjustment in a parameter storage device;
• and
• performing control so that the emission amount of the flash is adjusted to the adequate emission amount Ch, by calculating an average value of the provisional adequate value Cn and the provisional adequate value Cf, in which the influence of the provisional adequate value Cf on the calculation result varies according to the value of the parameter stored in the parameter storage device.

A digital camera, comprising:

• an imaging unit for generating image data representing a subject;
• a flash device for emitting a flash;
• a face detection unit for performing face detection on the image data generated by the imaging unit;
• and
• a flash control unit for controlling emission amount of the flash using a detection result outputted from the face detection unit, the flash control unit including:
• a calculation means for performing a calculation for each of N (integer number) faces detected by the face detection unit by regarding each face as the only face included in the image data and considering the face to obtain provisional adequate values Cfi (1≦i≦N) for the emission amount;
• and
• an emission amount determination means for determining an adequate emission amount Ch of the flash by performing an adjustment using the N provisional adequate values Cf1 to CfN supplied from the calculation means as reference values, wherein the emission amount determination means selects a smallest provisional adequate value from the N provisional adequate values Cf1 to CfN supplied from the calculation means, and performs the adjustment using the smallest provisional adequate value Cfmin as the reference value to determine the adequate emission amount Ch of the flash.

A method for controlling emission amount of a flash of a digital camera, the method comprising the steps of:

• providing, as components of the digital camera:
• an imaging unit for generating image data representing a subject;
• a flash device for emitting a flash;
• and a face detection unit for performing face detection on the image data generated by the imaging unit;
• obtaining a detection result outputted from the face detection unit;
• performing a calculation for each of N (integer number) faces detected by the face detection unit by regarding each face as the only face included in the image data and considering the face in the calculation to obtain provisional adequate values Cfi (1≦i≦N) for the emission amount;
• and
• determining an adequate emission amount Ch of the flash by performing an adjustment using the obtained N provisional adequate values Cf1 to CfN as reference values, wherein the determining step includes selecting a smallest provisional adequate value from the N provisional adequate values Cf1 to CfN, and performing the adjustment using the smallest provisional adequate value Cfmin as the reference value.

A digital camera, comprising:

• an imaging unit for generating image data representing a subject;
• a flash device for emitting a flash;
• a face detection unit for performing face detection on the image data generated by the imaging unit;
• and
• a flash control unit for controlling emission amount of the flash using a detection result outputted from the face detection unit, the flash control unit including:
• an emission amount determination means for determining an emission amount of the flash by performing a calculation process capable of setting a face consideration level as a calculation parameter in the determination of the emission amount;
• and
• a parameter setting means for obtaining index data representing an influence level of movement of the digital camera or the subject on the determination of the emission amount, and setting the calculation parameter to a value determined based on the index data, wherein:
• the emission amount determination means performs a process for obtaining the emission amount as the calculation process, based on a detection result of face detection performed on one image data set generated by the imaging unit, and a required amount of light for the subject estimated based on another image data set generated by the imaging unit;
• and
• the parameter setting means obtains a time lag between the time point when the one image data set is generated and the time point when the another image data set is generated as the index data, and sets the calculation parameter such that the greater the time lag the smaller the face consideration level when the time lag is at least within a predetermined range.