1. A method for defect detection, comprising: generating a first image of a first area of an wafer; registering the first image with respect to a computer aided design (CAD) data to provide a first registered image; generating a second image of a second area of an wafer; registering the second image with respect to the CAD data to provide a second registered image; detecting defects in response to a comparison between the first registered image and the second registered image; and generating defect location information in CAD coordinates.