The design and implementation of a high performance video enhancement instrument
Date
1985
Authors
Hewitt, Lawrence Bruce
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Abstract
A high speed instrument capable of digitizing , enhancing and displaying television images is presented. The instrument, called a Video Enhancement Instrument, uses two dimensional (2D) recursive Spatial Integrator filters for enhancing the images because of the reduced internal storage requirements and the reduced number of arithmetic operations when compared with other methods. The Instrument digitizes a (512 x 512) by 8 bit image in 1/30 second; enhances t hat image in approximately 4.0 seconds and instantaneously displays t he enhanced image . The design technique can be extended, by parallelism, to further reduce the time taken to enhance an image. In support of t he design method, an experimental comparison is provided of the implementation of a 2D Spatial Integrator filter with the implementation of a corresponding 2D Direct Form filter.
Highly acceptable recursive 2D Spatial Integrator filters of order (3 x 3) may be implemented with single precision 16 bit integer multiplier coefficients. 2D Direct Form filters of order (3 x 3) require 20 bit multiplier coefficients.
It is shown by examination of row-recursive 2D filtering, t hat t he ( n + l)th row of an image may be processed concurrently with the nth row, providing the recursion in the ( n + l)th row follows by one pixel, the recursion in the nth row. Therefore, an algorithm which is suitable for multiprocessor implementation is developed.
The Instrument consists of commercially available electronic circuitry for acquiring a single black and white image from a television camera and for displaying (512 x 512) by 8 bit images . The Instrument also contains a 2D Processor that has been specifically designed for 2D recursive filtering, a central controller to interface the user to the Instrument and to synchronize the 2D Processor to the Display Memory. The 2D Processor contains four high performance 16 bit TMS32010 microprocessors that are manufactured by Texas Instruments Inc. The Instrument provides twenty seven 2D filter transfer functions, a function for contrast stretching, and a function for histogram equalization.