1. A method, comprising: dividing shielded pixels in a row of an image sensor into a plurality of sub-regions, ones from the plurality of sub-regions including a plurality of shielded pixels; determining statistics of signal values associated with the plurality of sub-regions, wherein said determining comprises determining a statistic for ones from the plurality of sub-regions based on the signal values from the respective sub-region of the plurality of sub-regions; determining an offset based on the statistics; and updating a signal value of an active pixel in the row based on the offset.