Defective pixel data correcting apparatus, image capturing apparatus, and method for correcting defective pixel data
Among defective pixels of an image sensor, defective pixels which need to be corrected are determined depending on the type and defect level for individual defective pixels and on image capturing conditions. Depending on the types of the defective pixels, the correspondences between the image capturing conditions and the defect levels of the defective pixels to be corrected are prepared in advance, thereby carrying out appropriate defective pixel correction in view of the fact that the dependence of the abnormal signal output level on the image capturing conditions differs depending on the type of defective pixel.
1. A defective pixel data correcting apparatus for correcting defective pixel data output from a defective pixel of an image sensor, the defective pixel data contained in image data captured using the image sensor comprising a plurality of pixels, the defective pixel data correcting apparatus comprising:
a first storage unit adapted to store defective pixel information containing a type and a defective output level of a defective pixel, for each defective pixel included in the plurality of pixels;
a second storage unit adapted to store a plurality of correction tables each of which corresponding to one of types of the defective pixel, and associating the image capturing condition and a defective output level to be subjected to correction with each other;
a determination unit adapted to determine whether or not the defective pixel data needs to be corrected, based on the defective pixel information and at least one correction table that corresponds to the type of a defective pixel from which the defective pixel data is obtained, and the image capturing condition; and
a correction unit adapted to correct the defective pixel data that is determined, by the determination unit, to need to be corrected.
2. The defective pixel data correcting apparatus according to claim 1 , wherein the type of the defective pixel includes a first defective pixel for irregularly outputting an abnormal level signal and a second defective pixel for regularly outputting an abnormal level signal, and
the image capturing condition includes an environmental temperature of the image sensor and a charge accumulation period of the image sensor.
3. An image capturing apparatus comprising:
the image sensor; and
the defective pixel data correcting apparatus according to claim 1 .
4. The image capturing apparatus according to claim 3 , further comprising a detection unit for detecting a defective pixel included in the image sensor and a type of the defective pixel, from image data obtained by capturing a dark image using the image sensor under a predetermined image capturing condition,
wherein the predetermined image capturing condition differs depending on the type of the detected defective pixel.
5. The image capturing apparatus according to claim 4 , wherein the detection unit detects the first defective pixel and the second defective pixel from the image data obtained by capturing the dark image.
6. A defective pixel data correction method for correcting defective pixel data output from a defective pixel of an image sensor, the defective pixel data contained in image data captured using the image sensor comprising a plurality of pixels, the defective pixel data correction method comprising:
a first storage step of storing defective pixel information containing a type and a defective output level of a defective pixel, for each defective pixel included in the plurality of pixels;
a second storage step of storing a plurality of correction tables each of which corresponding to one of types of the defective pixel, and associating the image capturing condition and a defective output level to be subjected to correction with each other;
a determination step of determining whether or not the defective pixel data needs to be corrected, based on the defective pixel information and at least one correction table that corresponds to the type of a defective pixel from which the defective pixel data is obtained, and the image capturing condition; and
a correction step of correcting the defective pixel data that is determined, by the determination step, to need to be corrected.