VL6522

Detailed description

11/35

4

Detailed description

4.1

Image data pipeline (IDP)

4.1.1

Overview

The video processing blocks included in the VL6522 IDP are listed below:

●

Dark level compensation

●

Flicker cancellation

●

Statistics

●

Lens shading correction

●

Channel offset

●

Channel gain

●

Defect correction

●

Interpolation

●

Color matrix

●

Sharpening

●

Gamma correction

●

RGB to YUV 422

●

Automatic frame rate control

●

Fade to black

4.1.2

Dark level compensation

A dedicated DSP uses information from special dark lines within the pixel array to apply an

offset to the video data and ensure a consistent ‘black’ level.

4.1.3

Flicker cancellation

The 50/60 Hz flicker frequency present in the lighting (due to fluorescent lighting) can be

cancelled by the system.

4.1.4

Statistics

The function of the statistics processor is to gather statistics on Bayer IDP data. The

statistics are made available to the Imaging Control Bus Host for tasks such as automatic

exposure control and white balance.

4.1.5

Lens shading correction

The lens shading correction module is used to reduce the visible effect of vignetting where

inherent problems in lens design can cause non-uniformities in levels of light transmission

across the image plane. The extent of transmission loss is primarily a function of lens quality

and fabrication tolerances, but generally increases radially from the lens’ optical centre

towards the edges of the scene.