| 摘要 |
In an exposure control mechanism for a camera, and more particularly for a still video camera which obtains an image signal using an image sensor, a first preliminary exposure is conducted with almost all the center portion of an automatic exposure luminance range exposed to light of the most suitable exposure level. The specific number of pixels obtained through this exposure is limited to within the foregoing middle luminance range. However, since the total number of pixels are known, the total number of pixels saturated with image pick-up signals due to high exposure intensity in the portion recognized as white, and the total number of pixels in the portion recognized as black due to low exposure intensity, can be obtained by distribution data of pixels in an image pick-up screen with regard to the luminance level obtained by the first preliminary exposure. From the numbers of pixels in the portion recognized as white and in the portion recognized as black, the luminance information of the entire image pick-up screen, and rough information about the luminance distribution, are obtained, and a second preliminary exposure condition can be determined based upon the obtained information. Consequently, metering can be completed when preliminary exposure has been conducted twice. |
