Exposure control apparatus, image capturing apparatus and method of controlling exposure
There is provided an exposure control apparatus including a photometry amount acquisition unit for acquiring a measured light amount as a photometry amount; a light emission amount control unit for increasing a light emission amount of a light emission unit as the photometry amount is smaller when the photometry amount is within a certain light amount range; and a gain control unit for increasing a gain to an output signal of an image sensor as the photometry amount is smaller when the photometry amount is not within the light amount range and setting the gain to a constant value when the photometry amount is within the light amount range, an image capturing apparatus including the exposure control apparatus, and a method of controlling exposure using the apparatus.
1. An exposure control apparatus, comprising:
a photometry amount acquisition unit configured to acquire a measured light amount as a photometry amount;
a light emission amount control unit configured to increase a light emission amount of a light emission unit when the photometry amount is between a first threshold value and a second threshold value; and
a gain control unit configured to increase a gain to an output signal of an image sensor when the photometry amount is less than a third threshold value; and
the gain control unit configured to set the gain to a constant value when the photometry amount is between the third threshold value and a fourth threshold value.
2. The exposure control apparatus according to claim 1 , wherein
the light emission control unit turns on the light emission unit when the photometry amount acquired during the light emission unit is turned off is less than one of two threshold values, and turns off the light emission unit when the photometry amount acquired during the light emission unit is turned on exceeds the rest of the two threshold values.
3. An exposure control apparatus, comprising:
a photometry amount acquisition unit for acquiring a measured light amount as a photometry amount;
a light emission amount control unit for increasing a light emission amount of a light emission unit when the photometry amount is within a certain light amount range;
a gain control unit for increasing a gain to an output signal of an image sensor when the photometry amount is not within the light amount range and setting the gain to a constant value when the photometry amount is within the light amount range;
an exposure time control unit for controlling an exposure time of the image sensor by synchronizing with a timing signal having a frequency provided by multiplying a reference frequency; and
a pulse signal generation unit for generating a pulse signal having a frequency provided by multiplying the reference frequency,
wherein the light emission unit emits light depending on a pulse width of the pulse signal.
4. An exposure control apparatus, comprising:
a photometry amount acquisition unit for acquiring a measured light amount as a photometry amount;
a light emission amount control unit for increasing a light emission amount of a light emission when the photometry amount is within a certain light amount range;
a gain control unit for increasing a gain to an output signal of an image sensor when the photometry amount is not within the light amount range and setting the gain to a constant value when the photometry amount is within the light amount range;
an exposure time control unit for controlling an exposure time of the image sensor by synchronizing with a timing signal having a frequency provided by multiplying a reference frequency; and
a pulse signal generation unit for generating a pulse signal having a frequency provided by multiplying the reference frequency, wherein
the light emission unit emits light depending on a pulse width of the pulse signal,
the exposure time control unit starts to expose the image sensor by synchronizing with the timing signal, and
the light emission amount control unit starts to emit light in the light emission unit by synchronizing with the timing signal.
5. An image capturing apparatus, comprising:
a photometry amount acquisition unit configured to acquire a measured light amount as a photometry amount;
a light emission amount control unit configured to increase a light emission amount of a light emission unit when the photometry amount is between a first threshold value and a second threshold value; and
a gain control unit configured to increase the gain to the output signal of the image sensor when the photometry amount is less than a third threshold value; and
the gain control unit configured to set the gain to a constant value when the photometry amount is between the third threshold value and a fourth threshold value; and
an image capturing unit for image capturing an image including the output signal.
6. A method of controlling exposure, comprising:
acquiring a measured light amount as a photometry amount;
controlling a light emission amount by increasing a light emission amount of a light emission unit when the photometry amount is between a first threshold value and a second threshold value; and
controlling a gain by increasing the gain to the output signal of the image sensor when the photometry amount is less than a third threshold value and setting the gain to a constant value when the photometry amount is between the third threshold value and a fourth threshold value.
7. The image capturing apparatus according to claim 5 , wherein
the light emission control unit turns on the light emission unit when the photometry amount acquired during the light emission unit is turned off is less than one of two threshold values, and turns off the light emission unit when the photometry amount acquired during the light emission unit is turned on exceeds the rest of the two threshold values.
8. The image capturing apparatus according to claim 5 , further comprising:
an exposure time control unit for controlling an exposure time of the image sensor by synchronizing with a timing signal having a frequency provided by multiplying a reference frequency; and
a pulse signal generation unit for generating a pulse signal having a frequency provided by multiplying the reference frequency,
wherein the light emission unit emits light depending on a pulse width of the pulse signal.
9. The image capturing apparatus according to claim 8 , wherein
the exposure time control unit starts to expose the image sensor by synchronizing with the timing signal, and
the light emission amount control unit starts to emit light in the light emission unit by synchronizing with the timing signal.
10. The exposure control apparatus according to claim 1 , further comprising:
an exposure time control unit for controlling an exposure time of the image sensor by synchronizing with a timing signal having a frequency provided by multiplying a reference frequency; and
a pulse signal generation unit for generating a pulse signal having a frequency provided by multiplying the reference frequency,
wherein the light emission unit emits light depending on a pulse width of the pulse signal.
11. The exposure control apparatus according to claim 3 , wherein
the exposure time control unit starts to expose the image sensor by synchronizing with the timing signal, and
the light emission amount control unit starts to emit light in the light emission unit by synchronizing with the timing signal.
12. The exposure control apparatus according to claim 1 , wherein
the third threshold value and the fourth threshold value are less than the first threshold value and the second threshold value.
13. The image capturing apparatus according to claim 5 , wherein
the third threshold value and the fourth threshold value are less than the first threshold value and the second threshold value.
14. The method of controlling exposure according to claim 6 , wherein
the third threshold value and the fourth threshold value are less than the first threshold value and the second threshold value.