A study is reported of the extraction of two-level cartoons from moving grey-level images for visual communication in the range 48-192 kbits/s It is postulated that perceptually significant features of the human face and hands, at which cartoon lines should be drawn in the image, occur wherever surfaces in object space are approximately tangential to the line of sight of the camera or viewer The implications of this postulate are analyzed for smooth lambertian reflectors seen against a background of the same luminance factor; it is shown that the combined effects of surface gradient and illumination lead to the formation of luminance valleys at the significant features An experimental comparison of several detectors is described which confirmed the advantage of valley-based detection for deriving economical but recognizable cartoons

Visual communication at very low data rates

Laboratory experiments for image processing courses are usually software implementations of processing algorithms, but students of image processing come from diverse backgrounds with widely differing software experience. To avoid learning overhead, the software system should be easy to learn and use, even for those with no exposure to mathematical programming languages or object-oriented programming. The class library for image processing (CLIP) supports users with knowledge of C, by providing three C++ types with small public interfaces, including natural and efficient operator overloading. CLIP programs are compact and fast. Experience in using the system in undergraduate and graduate teaching indicates that it supports subject matter learning with little distraction from language/system learning.

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A software system for laboratory experiments in image processing

The 'Class Library for Image Processing' (CLIP) provides object-oriented programming facilities in a framework that supports user migration from C. CLIP augments the C/C++ built-in types with just three additions: the picture, the integer range, and the value range. Associated with these are overloaded operators for arithmetic on and between the types. Range limiting is implemented as a modification of conventional indexing. Pel-by-pel and block-by-block iterations are conveniently handled within the picture and range objects, and via callbacks. Each type incorporates error handling. The target users for CLIP will accept object-orientation only it if allows them to save on development time, after minimal learning, without compromising program execution speed. CLIP programs are compact, the required knowledge of C++ is elementary, and the class library's public interface is small. Speed is kept high by minimizing the amount of data in temporary objects, reducing the dynamic memory management overhead. Picture- or block-wide operations and callbacks are efficiently supported by ordering iterations to minimize the number of counter and pointer increments.

C++ class library for teaching and research in image processing

A real-time parallel processor named PETAL is described which has been developed to extract cartoon primitives from grey-level television images. It is based on a cascaded look-up table architecture and is controlled by a 68000 microprocessor. It can process 256x256 images at 50 frames/s.

/pdf/petal-a-parallel-processor-for-real-time-primitive-6specsc833.pdf

PETAL: A Parallel Processor For Real-Time Primitive Extraction

A real -time parallel processor named PETAL is described which has been developed to extract cartoon primitives from grey -level television images It is based on a cascaded look -up table architecture and is controlled by a 68000 microcomputer It can process 256x256 images at 50 frames /s

Figure 1 An example of a cartoon extracted from a grey -level image

We describe the architecture of a real-time feature extractor used in the encoding of simple moving pictures into 10 kbit/s or less. A central Motorola MC68000 processor controls several NEC μPD 7720 signal-processing chips as hardware subroutines to provide the necessary speed and flexibility.

S. Mizuno

Papers

Real-Time feature-extraction architecture for moving-picture transmission over telephone lines