Image-correction method and image pickup apparatus

An image-correction method, comprising:

• a horizontal-direction distance calculating step of calculating the horizontal-direction distance between the coordinates of an image-constituting pixel and predetermined reference coordinates;
• a horizontal-direction distance-correction value calculating step of calculating a horizontal-direction distance-correction value, by inputting for the variable in a first N-order function (N being a positive integer) the horizontal-direction distance that has been calculated in the horizontal-direction distance calculating step;
• a first correction coefficient calculating step of calculating, based on a first table that represents correspondences between horizontal-direction distance-correction values and first correction coefficients, a first correction coefficient corresponding to the horizontal-direction distance-correction value that has been calculated in the horizontal-direction distance-correction value calculating step;
• a vertical-direction distance calculating step of calculating the vertical-direction distance between the coordinates of an image-constituting pixel and predetermined reference coordinates;
• a vertical-direction distance-correction value calculating step of calculating a vertical-direction distance-correction value, by inputting for the variable in a second N-order function (N being a positive integer) the vertical-direction distance that has been calculated in the vertical-direction distance calculating step;
• a second correction coefficient calculating step of calculating, based on a second table that represents correspondences between vertical-direction distance-correction values and second correction coefficients, a second correction coefficient corresponding to the vertical-direction distance-correction value that has been calculated in the vertical-direction distance-correction value calculating step;
• and
• a pixel signal correcting step of correcting a signal for the pixel, based on the first correction coefficient that has been calculated in the first correction coefficient calculating step and on the second correction coefficient that has been calculated in the second correction coefficient calculating step an updating step of updating distance-correction values by individually changing the coefficients for the input variable in said first N-order function in the horizontal-direction distance-correction value calculating step and said second N-order function in the vertical-direction distance-correction value calculating step in response to change in optical settings including setting of a diaphragm mechanism and setting of an optical zooming function of an optical system of said image pick-up apparatus, said optical system directing light onto said solid-state image pickup device.

An image pickup apparatus, comprising:

• a solid-state image pickup device;
• an optical system that directs light onto said solid-state image pickup device;
• a distance calculating unit that calculates a distance between the coordinates of an image-constituting pixel obtained by said solid-state image pickup device and predetermined reference coordinates;
• a distance-correction value calculating unit that receives the calculated distance as an input variable of an N-order function having a plurality of coefficients for the input variable and calculates a distance-correction value as an output value of the N-order function, N being a positive integer greater than or equal to 2;
• a correction coefficient calculating unit that calculates, based on a preliminarily set table that represents correspondences between distance-correction values and correction coefficients, a correction coefficient corresponding to the distance-correction value that has been calculated by the distance-correction value calculating unit;
• a pixel signal correcting unit that corrects a signal for the pixel based on the correction coefficient that has been calculated by the correction coefficient calculating unit;
• and
• a control unit that updates distance-correction values by individually changing the coefficients for the input variable in said N-order function in the distance-correction value calculating unit in response to change in optical settings including setting of a diaphragm mechanism and setting of an optical zooming function of said optical system.

An image pickup apparatus, comprising:

• a horizontal-direction distance calculating means for calculating the horizontal-direction distance between the coordinates of an image-constituting pixel and predetermined reference coordinates;
• a horizontal-direction distance-correction value calculating means for calculating a horizontal-direction distance-correction value, by inputting for the variable in a first N-order function (N being a positive integer) the horizontal-direction distance that has been calculated in the horizontal-direction distance calculating means;
• a first correction coefficient calculating means for calculating, based on a first table that represents correspondences between horizontal-direction distance-correction values and first correction coefficients, a first correction coefficient corresponding to the horizontal-direction distance-correction value that has been calculated in the horizontal-direction distance-correction value calculating means;
• a vertical-direction distance calculating means for calculating the vertical-direction distance between the coordinates of an image-constituting pixel and predetermined reference coordinates;
• a vertical-direction distance-correction value calculating means for calculating a vertical-direction distance-correction value, by inputting for the variable in a second N-order function (N being a positive integer) the vertical-direction distance that has been calculated in the vertical-direction distance calculating means;
• a second correction coefficient calculating means for calculating, based on a second table that represents correspondences between vertical-direction distance-correction values and second correction coefficients, a second correction coefficient corresponding to the vertical-direction distance-correction value that has been calculated in the vertical-direction distance-correction value calculating means;
• and
• a pixel signal correcting means for correcting a signal for the pixel, based on the first correction coefficient that has been calculated in the first correction coefficient calculating means and on the second correction coefficient that has been calculated in the second correction coefficient calculating means a control unit that updates distance-correction values by individually changing the coefficients for the input variable in said first N-order function in the horizontal-direction distance-correction value calculating unit and said second N-order function in the vertical-direction distance-correction value calculating unit in response to change in optical settings including setting of a diaphragm mechanism and setting of an optical zooming function of said optical system.