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US 7,187,409 B2Granted
Level difference correcting method and image pick-up device using the method
AssigneeRicoh Company, Ltd.
InventorsToshiaki Nakahira, Akihiro Yoshida
Life of this patent
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Abstract
An OB level difference is calculated from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, and the OB level difference is corrected in an input step of a signal processing circuit. Calculation of the OB level difference is performed regularly from immediately after power on of the equipment, the OB level difference obtained in each frame is multiplied, and a value obtained by dividing the multiplied OB level difference by the number of sampled frames is designated as a correction value.
Claims32
A picture signal processing method comprising:
- calculating OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal;
- and
- correcting the OB level difference in an input step of a signal processing circuit, wherein
- calculation of the OB level difference is regularly performed from immediately after power on of the equipment, the OB level difference obtained in each frame is multiplied, and a value obtained by dividing the multiplied OB level difference by the number of sampled frames is designated as a correction value, and when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, it is controlled such that the result is excluded from averaging.
1 more element
A picture signal processing method comprising:
- calculating an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal;
- and
- correcting the OB level difference in an input step of a signal processing circuit, wherein
- calculation of the OB level difference is regularly performed from immediately after power on of the equipment and periodically with an interval of certain period, to multiply the OB level difference obtained in each frame, and a value obtained by dividing the obtained OB level difference by the number of sampled frames is designated as a correction value and when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, it is controlled such that the result is excluded from averaging.
1 more element
A picture signal processing method comprising:
- calculating an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal;
- and
- correcting the OB level difference in an input step of a signal processing circuit, wherein
- calculation of the OB level difference is performed at a limited time when performing a focusing operation, and when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, it is controlled such that the result is excluded from averaging.
1 more element
A picture signal processing method comprising:
- calculating an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal;
- and
- correcting the OB level difference in an input step of a signal processing circuit, wherein
- calculation of the OB level difference is performed when a change in an automatic exposure control value is small, and when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, it is controlled such that the result is excluded from averaging.
1 more element
A picture signal processing apparatus comprising:
- an OB level difference correction circuit which calculates an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal, and corrects the OB level difference in an input step of a signal processing circuit, wherein the OB level difference correction circuit performs calculation of the OB level difference regularly from immediately after power on of the equipment, multiplies the OB level difference obtained in each frame, and designates a value obtained by dividing the multiplied OB level difference by the number of sampled frames as a correction value;
- and
- a control unit which controls the OB level difference correction circuit, so that when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, the result is excluded from averaging.
A picture signal processing apparatus comprising:
- an OB level difference correction circuit which calculates an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal, and corrects the OB level difference in an input step of a signal processing circuit, wherein the OB level difference correction circuit performs calculation of the OB level difference immediately after power on of the equipment and periodically with an interval of certain period, multiplies the OB level difference obtained in each frame, and designates a value obtained by dividing the multiplied OB level difference by the number of sampled frames as a correction value;
- and
- a control unit which controls the OB level difference correction circuit, so that when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, this the result is excluded from averaging.
A picture signal processing apparatus comprising:
- an OB level difference correction circuit which calculates an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal, and corrects the OB level difference in an input step of a signal processing circuit, wherein the OB level difference correction circuit performs calculation of the correction value at a limited time when performing a focusing operation;
- and
- a control unit which controls the OB level difference correction circuit, so that when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, this the result is excluded from averaging.
A picture signal processing apparatus comprising:
- an OB level difference correction circuit which calculates an OB level difference from the luminance signal levels of at least two frames which are exposed for proper exposure time and for exposure time different from the proper exposure time, the OB level difference being a difference in black level, which is a difference between an optical black level, being an electrical output level when there is no optical input with respect to a two-dimensional CCD image pickup device, and a black level of a picture signal, and corrects the OB level difference in an input step of a signal processing circuit, wherein the OB level difference correction circuit performs calculation of the correction value when a change in an automatic exposure control value is small;
- and
- a control unit which controls the OB level difference correction circuit, so that when the result of calculation of the OB level difference considerably differs from the last result and exceeds a preset threshold, the result is excluded from averaging.
Dependencies are inferred from the claim text.