There are provided a system and method of examination on a specimen, the method comprising: obtaining an inspection image of a die and generating a defect map using one or more reference images; selecting a plurality of defect candidates from the defect map; and generating for each defect candidate, a respective modified inspection image patch, comprising: extracting an image patch surrounding the defect candidate respectively from the inspection image and each reference image; and modifying the inspection image patch, comprising: estimating noise representative of intensity variations on the inspection image patch, the noise including a first type of noise representative of a polynomial relation between the inspection and reference image patches, and a second type of noise representative of a spatial anomaly in the inspection image patch, and removing at least one of the first and second types of noise from the inspection image patch based on the estimated noise.