Digitizing Units
Structure
A digitizing unit is a set of analog and digital resources aimed at conditioning an analog video signal and transforming it into a digital format.
The digitizing unit receives the analog information from a video lane and delivers this information in a digital form to the internal frame buffer.
The Domino Iota board owns one high performance digitizing unit, referred to as A.
Before storing the image into the frame buffer, the data issued by the digitizing unit is re-arranged in a consistent way. The idea is that, whatever the digitizing unit assignment to a camera, the digital image deposited into the frame buffer is a well-organized array of 8-bit pixels exactly representing the camera picture.
Look-Up Table
The digitizing unit includes a transformation table operating in real-time. The purpose is to establish a one-to-one map for each gray value delivered by the digitizer towards another set of values previously entered in a table.
This is figured in the following drawing.
Look-up table
The look-up table device can be thought as a high-speed memory belonging to the digitizing unit.
This memory is addressed by the data coming from the digitizer, and the read data is the transformed data. For each pixel delivered at the sampling rate, the table issues a value depending on the digitized gray-level and on the contents of the memory.
The user is provided with software means to load the table in advance. The loaded contents implement the transformation law that will be applied to the data flow when acquisition proceeds.
The Domino Iota look-up table is an 8 x 8 device because both input and output ports are 8-bit wide.
Refer to user note "How to control the look-up tables in Alpha" for full details.