Camera Processing Blocks

Defective Pixels Correction corrects for pixels which are either short circuits (white), and open circuits (black). The Himax HM1246 camera “identifies and corrects hot (white) and cold (black) pixels by comparing each pixel to neighboring same color pixels.”
Video Cropping works much like photo cropping. It is a bit more complex, because the process has to be synchronized with the Vertical (VSync) and horizontal (HSync) synchronization ignals.

Black Level Calibration compensates for image sensors output voltage which have a non-zero offset when no light is shining on them. Many cameras have a blackened area to measure and deduct the average offset value from each measurement's nominal value.

Lense Shade Correction fixes visible hue changes caused by the lens and its housing at the edges of the sensor array.

Exposure Controls sets the length of time for which charge is accumulated on the sensor, based on the lighting condition.

Binning averages input measurements prior to debayering. The OV5640 supports 1x2, 2x1 and 2x2 binning.

Debayering converts a grid of red, green and blue measurements into an image, where each pixel has red green and blue components.  Most cameras have a single sensor backplane, with a grid of color filters in front of it. This original Bayer pattern is half green, one quarter red and one quarter blue. Debayering converts those measurements into one quarter as many pixels, each with 3 colors.

Lens correction compensates for errors in the lens manufacturing process.  Lenses have a designed shape, but the actual manufactured shape may differ from the designed shape.

50/60 Hz Luminance Detection prevents bands in the image caused by fluorescent lights flickering at 50 or 60 hz.   This happens because most commercial cameras use a rolling shutter. Wikipedia says that: “rolling shutter is a process of image capture in which … each frame of a video (in a video camera) is captured not by taking a snapshot of the entire scene at a single instant in time but rather by scanning across the scene rapidly.” So the lines recorded during the dark part of the fluorescent flicker will look different from the lines recorded during the bright part of the flicker. OV5640 and other cameras detect and correct for this effect.