In an image pickup apparatus, a level compensator compensates the level of an image xL (i, j) sensed by an image sensor by exposure for a long time on the basis of the exposure of the image to produce a compensated image xL' (i, j), while another level compensator compensates the level of an image xS (i, j) sensed by the image sensor by exposure for a short time on the basis of the exposure of the image to produce a compensated image xS' (i, j). The image pickup apparatus also includes an image synthesizer to synthesize these compensates images xL' (i, j) and xS' (i, j) to produce a single synthetic image x (i, j). A dynamic range compressor also included in the image pickup apparatus compresses the synthetic image x (i, j) to produce a compressed image y (i, j) for delivery to outside.

A method of broadening a dynamic range is applied to a solid-state image sensor of the type including photodiodes each being divided into a main and a subregion different in photosensitivity from each other. While the quantity of light to be incident on a photodiode is reduced, a signal charge is read out only from the main region of the photodiode. The signal charge is digitized and then written to two image memories. Digital signals thus stored in the image memories are respectively amplified by white balance gain circuits with different gains. The resulting digital signals are combined by an image synthesizer. The method can therefore broaden the dynamic range of the image sensor by using only the main regions of the photodiodes.

Providing a signal processing method for image synthesis with reduced computation load, a signal processor circuit for image synthesis with reduced computation load which allows manufacturing at a low production cost, and imaging apparatus which uses the signal processing method and the signal processor circuit. The signal processor circuit includes: a table storage area for storing an LUT; a table overwriting section for overwriting an LUT written into the table storage area with another LUT; and an arithmetic operation section for performing arithmetic operation on a first digital signal or a second digital signal based on the LUT written into the table storage area each time an LUT is written into the table storage area and synthesizing the first digital signal and the second digital signal.

An imaging device which assures high-quality image information free from a line noise by extracting line noise information from a taken image, detecting an existence of an extrinsic line noise in the image, and correcting the line noise if it exists. The imaging device comprises a memory circuit for storing image pick-up outputs at imaging of a two-dimensional area sensor comprising photosensors or radiation sensors, an extrinsic line noise detection unit for detecting an extrinsic line noise in the image pick-up outputs stored in the memory circuit, and an arithmetic processing circuit for calculating an output quantity of the detected extrinsic line noise. The line noise is eliminated by correcting the image pick-up outputs on the basis of the obtained output quantity of the extrinsic line noise.

An object of this invention is to correct the non uniformity between a plurality of image sensing regions in real time and cope with even dynamic variations such as temperature variations or variations over time. To achieve this object, a correction apparatus includes a plurality of level adjustment devices which independently adjust the levels of a plurality of image sensing signals output from a plurality of output terminals, an output level detection device which detects the output levels of the plurality of level adjustment devices, and a correction coefficient determination device which determines a correction coefficient for reducing the level difference between the image sensing signals on the basis of the detection result of the output level detection device. The correction coefficient determination device determines the correction coefficient by excluding an object-dependent level difference component in which the level difference between the plurality of image sensing signals exceeds a predetermined level difference. The correction coefficient determination device supplies the determined correction coefficient to the level adjustment devices to perform adjustment so as to reduce the level difference between the image sensing signals.