QT – Prototyping Image Processing System

QT is the latest in a series of interactive image processing tool-kits for prototype development of Machine Vision systems. Experience gained over more than 35 years has shown that a command-line system with short mnemonic function names is an effective tool for developing vision algorithms. Parameter lists are also required for some functions. When the user types a command, such as neg (negate), thr(89,127) (threshold) or lpf (low-pass filter, blur), the operation is performed immediately and the result is displayed, together with the image before processing. When running on a modern computer, typical response times for processing an image of good resolution are rarely more that one second. Measurements are obtained in an obvious way. For example, to count the number of distinct objects (blobs) in a binary image, the user types x = cbl, while the command y = avg computes the average intensity in a grey-scale image. Binary, grey-scale and colour images are all processed by QT, which is built on top of MATLAB™. The advantage of QT over MATLAB lies in its greater ease of use. The command names are short but most importantly, the user does not have to keep track of source and destination images. QT always processes the image displayed on the left of the computer screen. It then replaces this with the result of the operation selected by the user and displays the input image for the last processing step on the right. In addition, to image processing commands, QT provides facilities for a range of other operations, including image capture from local or remote cameras, controlling external devices, speech synthesis, on-line documentation, consulting the Catalogue of Lighting-Viewing methods (Chap.​ 40). Any MATLAB function can be invoked from QT and programming new functions is straightforward. Many of the illustrations in the book were prepared using QT and several chapters exploit its ability to express image processing algorithms succinctly. Since it is a prototyping tool, QT is not fast enough for any but the least demanding factory applications. However, it is a powerful exploratory tool in the hands of an experienced user. On numerous occasions, QT or one of its predecessors, has been used to discover/invent algorithms very quickly in response to new visual inspection and control applications. QT has been interfaced to Prolog to produce an even more powerful language (PQT) that facilitates intelligent reasoning about images (Chap.​ 23).