Camera with image enhancement functions
View Patent ↗Imaging apparatus ( 20, 44 ) includes an array ( 22 ) of optical sensing elements ( 24 ), characterized by a pitch, which is adapted to generate a signal in response to optical radiation that is incident on the elements. Objective optics ( 26, 46 ), which have an optical axis ( 134 ) and are characterized by a cylindrical symmetry about the axis, are arranged to focus the optical radiation from an object onto the array with a point spread function (PSF) having an extent greater than twice the pitch of the array at an optimal focus of the objective optics.
1. Imaging apparatus, comprising:
objective optics, which are arranged to focus optical radiation from an object onto a focal plane with a characteristic point spread function (PSF);
an array of optical sensing elements, which is positioned at the focal plane and is adapted to generate a signal in response to the optical radiation that is incident on the elements, the signal corresponding to an electronic image of the object comprising pixels having respective pixel values;
an image processor, which is coupled to receive the signal from the array and is adapted to identify one or more bad elements in the array and, responsively to the PSF, to modify the pixel values of the pixels in a vicinity of the bad elements in the input image so as to produce a corrected blurred image while reducing propagation of artifacts due to the bad elements, and to apply a deconvolution filter, based on the PSF, to the corrected blurred image so as to generate a restored output image,
wherein the image processor is adapted to determine substitute values with which to replace the pixel values of the bad pixels responsively to the PSF using a correction map M[x]substantially of a form given by
M
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wherein x is a pixel coordinate, and M′[x]is a convolved map given by a convolution of a map of the bad elements with a conjugate of the PSF.
2. The apparatus according to claim 1 , wherein the image processor is adapted to iteratively modify the pixel values of the pixels in the vicinity of the bad elements in the restored image, so as to produce a new blurred image, and to apply the deconvolution filter to the new blurred image so as to generate a new restored image, until the electronic image with the reduced blur is generated for output.
3. The apparatus according to claim 1 , wherein the image processor is adapted to add a frame of dummy pixels surrounding the input image, and to treat the dummy pixels similarly to the pixels associated with the bad elements in producing the corrected blurred image and generating the electronic image for output.