Image analysis – Image enhancement or restoration – Intensity – brightness – contrast – or shading correction
Reexamination Certificate
1998-03-31
2001-01-30
Rogers, Scott (Department: 2724)
Image analysis
Image enhancement or restoration
Intensity, brightness, contrast, or shading correction
C382S275000, C348S246000, C348S251000
Reexamination Certificate
active
06181830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image signal correction device by which an image signal, obtained by an imaging device, is subjected to a shading correction and a defect correction.
2. Description of the Related Art
Conventionally, in an electronic still camera, each pixel data, corresponding to a part of an image formed on an imaging device, such as a solid-state imaging device, needs to be subjected to a shading correction and a defect correction. The shading correction is carried out for correcting a shade (or a darkness) generated around the periphery of the image, due to the inherent characteristics of an optical element, such as a lens. The defect correction is performed in order to eliminate an effect of a defective pixel (i.e. a defective photo-diode), existing in the imaging device. Thus, the correction device provided in the electronic still camera is provided with a first memory, in which a defect pixel data, such as an address and a flag, indicating a defect pixel position, is stored for each pixel, and a second memory, in which a shading correction data, indicating a correction ratio of the shading, is stored for each pixel.
As described above, in the conventional correction device, since the defect pixel data and the shading correction data are stored in separate memories, each of the memories requires a relatively large capacity.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to provide an image signal correction device by which a capacity of a memory, necessary for storing the defect pixel data and the shading correction data, can be reduced.
According to the present invention, there is provided an image signal correction device comprising a memory in which a shading correction data, corresponding to a pixel data forming a part of an image obtained by an imaging device, is stored, and a correction processor for performing a predetermined defect correction. The correction processor performes the shading correction data from the memory to perform the shading correction to the pixel data when the shading correction data has a predetermined value. The correction processor applies the predetermined defect correction to the pixel data when the shading correction data has a value other than the predetermined value.
Further, according to the present invention, there is provided an image signal correction device, in which a data, included in shading correction data composed of data of a plurality of gradations, is used as a defect pixel data implying that a data of a pixel, which corresponds to the defect pixel data, has a defect.
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patent: 4600946 (1986-07-01), Levine
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patent: 8-251484 (1996-09-01), None
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Rogers Scott
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