Image input apparatus

An image input apparatus comprising:

• an image sensing device with an input-output characteristic varying with a plurality of regions delimited in accordance with a difference in the amount of incident light;
• an incident light amount level detection section that outputs a video luminance signal level of a video signal representative of a picture taken by said image sensing device;
• an on-screen light amount calculation section that calculates an amount of light on a screen of said video signal from said video luminance signal level;
• a target light amount value setting section that selectively sets a target value R for said amount of light on the screen based on information on change points for said plurality of regions;
• and
• an exposure control section that adjusts an exposure time or output gain of said image sensing device so as to make said amount of light on the screen coincide with said target amount of light R;
• wherein said target light amount value setting section sets said target amount of light R in such a manner that a relation between an amount of light Q at that one of said change points for said plurality of regions that is at the lowest luminance and said target amount of light R satisfies the following requirement;
• R<Q, when it is determined that R is greater than or equal to Q.