Television – Camera – system and detail – Combined image signal generator and general image signal...
Reexamination Certificate
1999-02-01
2003-11-04
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Combined image signal generator and general image signal...
C348S247000, C348S273000, C382S272000
Reexamination Certificate
active
06642960
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to image pickup apparatus, and more particularly relates to an image pickup apparatus in which fault pixels of a semiconductor image pickup device can be interpolated and compensated at high accuracy.
In general, when an image is taken by using an image pickup apparatus having a semiconductor image pickup device which comprises two-dimensionally arrayed pixels, faults occur in image pickup signal and a poor image output results when defect occurs in the pixels of the semiconductor image pickup device. Means of various kinds for compensating pixel defects have been used to make less conspicuous such defects in the output image. Known among the fundamental compensation systems is a system in which signals of the pixels around a fault pixel are used to replace the signal of the fault pixel (4-point interpolation system).
Further, Japanese Patent Publication No. 5-23551 discloses an image defect compensation apparatus in which fault pixel signals can be compensated more accurately by reducing compensation error. It includes: an absolute value operation means for outputting absolute value signals by computing from pixel signals outputted from a plurality of image pickup devices arranged in a square matrix, absolute values of difference between respective two pixels between which a fault pixel signal is sandwiched in vertical, horizontal and slanting directions; a minimum difference detection means for detecting two pixel signals from which the smallest of the absolute value signals is derived; an average value operation means for computing an average value of the two pixel signals detected by the minimum difference detection means and outputting an average value signal; and a replacing means for replacing the fault pixel signal by the average value signal.
Here, supposing as shown in
FIG. 1A
a pixel
101
at the location indicated by a blank in the two pixel rows for outputting a black line in the horizontal direction as a fault pixel, a defect compensation system based on the 4-point compensation of surrounding pixels as described above is the system in which the fault pixel is replaced by an average value of those pixels indicated by the arrows, located above, below, and on the left and right sides of the fault pixel
101
. When the fault pixel
101
shown in
FIG. 1A
is interpolated by this system, the interpolation using the average value results in an interpolation by a gray level as shown in
FIG. 1B
, since three pixels out of those used for interpolation are black and the other one is white. Thus, the fault pixel shown in
FIG. 1A
, while it should be interpolated by black, is interpolated by gray and some of the defect is uncorrected. If, therefore, the defect is in a region (for example a line or edge) where a steep change in luminance occurs within the image, a problem is caused that the interpolation error becomes greater and an effective compensation of the fault pixel is impossible. Further, according to the above described image defect compensation apparatus disclosed in Japanese Patent Publication No. 5-23551, though the compensation error becomes smaller and it is possible to compensate the fault pixel at high accuracy, only the two pixels by which the fault pixel is sandwiched in the vertical, horizontal or slanting directions are considered and hence the manner of pixel signals in a region surrounding the fault pixel cannot be accurately considered. This also results in a problem that a compensation of the fault pixel at high accuracy may not be possible in a region where luminance is steeply changing.
SUMMARY OF THE INVENTION
To eliminate the above problems in the fault pixel compensation systems used in conventional image pickup apparatus, it is a main object of the present invention to provide an image pickup apparatus in which fault pixels can be compensated at high accuracy so as to make defect less conspicuous even when the defect is in a region where luminance steeply changes within an output image, by considering an image configuration in the region surrounding the fault pixels.
In a first aspect of the present invention, there is provided an image pickup apparatus including: an image pickup means having a semiconductor image pickup device composed of two-dimensionally arrayed pixels, for converting object light into image signals; a fault pixel detection means for obtaining the position of fault pixels in the semiconductor image pickup device and, if the fault pixels are two-dimensionally consecutive, additionally obtaining a pattern of order of the fault pixels; a fault pixel information storage means for storing information concerning the fault pixels obtained at the fault pixel detection means; a surrounding image configuration detection means for detecting from information of pixels surrounding the fault pixels an image configuration of a region surrounding a fault pixel location obtained by the fault pixel detection means in the image signals obtained from the image pickup means; and a pixel defect compensation means for selecting pixels from a surrounding of the fault pixels based on the image configuration detected by the surrounding image configuration detection means and performing pixel defect compensation by interpolating the fault pixels using the selected pixels.
Since the image configuration (line and its direction, edge and its direction, surface) of a region surrounding the fault pixels within an image is thus detected by the surrounding image configuration detection means and the pixels for interpolating the fault pixels are selected based on the image configuration, it is possible to achieve an image pickup apparatus in which compensation at high accuracy is possible so as to make defect less conspicuous even when the defect occurs in a region (for example line or edge) where luminance changes steeply in the output image. The above main object is thereby accomplished.
It is another object of the present invention to provide an image pickup apparatus in which, when fault pixels are two-dimensionally consecutive, processing for defect compensation is possible by a storage means having a relatively small memory capacity.
In a second aspect of the invention, the fault pixel information storage means in the image pickup apparatus according to the above first aspect, when fault pixels are two-dimensionally consecutive, stores the pixel location of one of the consecutive fault pixels and a pattern of order of the other fault pixels. Since the location of one of the fault pixels and order of the other fault pixels are stored as described if the fault pixels are two-dimensionally consecutive, a smaller memory capacity suffices when compared with the case of storing fault pixel location for each one pixel. The above object is thereby accomplished.
It is still another object of the present invention to provide an image pickup apparatus in which fault pixels can be accurately compensated by detecting at high accuracy an image configuration of a region surrounding a fault pixel location.
In a third aspect of the invention, the surrounding image configuration detection means in the image pickup apparatus according to the above first or second aspect includes: a signal level detection means for obtaining respective signal levels of a plurality of pixels surrounding a fault pixel; a first relative level detection means for, of signal level data of the plurality of pixels obtained from the signal level detection means, placing those of a plurality of pixels located above the fault pixel together into a horizontally oriented group, the signal level of one pixel in the group used as a reference pixel signal level to obtain relative signal levels of the other pixels with respect to the reference pixel signal level; a second relative level detection means for, of signal level data of the plurality of pixels obtained from the signal level detection means, placing those of a plurality of pixels located below the fault pixel together into a horizontally oriented group, the signal level of one pixel
Kawase Dai
Kohashi Atsushi
Armstrong Westerman & Hattori, LLP
Garber Wendy R.
Olympus Optical Co,. Ltd.
Ye Lin
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