Recognising the importance of partition or shape coding in the field of image and video coding, and the fact that a systematisation of the subject would simplify the comparison of partition coding techniques, this paper proposes a classification of partition types and partition representations into a taxonomy tree. The partition type level of the tree classifies the possible partition types that may have to be coded. The partition representation level classifies the possible representations for each partition type. This paper also overviews the partition coding techniques which address the considered partition types and which use the identified partition representations. Emphasis is given to binary partition coding techniques proposed within the framework of MPEG-4.

Partitions: A taxonomy of types and representations and an overview of coding techniques

Image representation by a new optimal non-uniform morphological sampling

To transmit facsimile images through a very low bit-rate channel such as the half-rate mobile channel, a very efficient codingscheme for data compression is required. Lossy coding is expected to perform more data reduction than that achieved by theconventional lossless coding schemes. This paper discusses approximate representation of scanned character patterns for datareduction. First, the quality of character patterns is considered in terms of the size of patterns. According to this consideration, the attributes of scanned character patterns and the quality associated with them are assumed. For preserving quality under approximation, a character pattern is described by a set of strokes in tree data structure.Keywords: binary image, character pattern, shape description, shape approximation, stroke-based description 1. INTRODUCTION A demand for transmission of multimedia data with mobile systems has recently been getting greater. The digital voice codecof the half-rate, say, 3.45kbpsby PSI-CELP method, has been developed for the land mobile phones. To transmit facsimileimages through such a very low bit-rate channel in practicable transmission time, a data reduction scheme more effective thanthe conventional facsimile coding schemes is required. Many coding schemes for facsimile transmission have been proposed so

Lossy coding scheme of binary character patterns

This paper presents a recursive morphological operation which can be advantageously substituted to classical erosion with an application for image coding. A structuring element is translated over binary image following four scanning modes. The result of the operation, as for classical erosion, corresponds to the centers of the structuring elements which are included in the image objects, but our operation authorizes only a minimal overlap between the translated structuring elements. This minimal overlap needs to take into account previous erosions, so the operation is recursive. It results in a subset of the erosion, containing fewer points than the erosion, but gives a good approximation to image objects. In a second step, operation is extended with a second recursivity level corresponding to structuring element size variation. This new double-recursive morphological algorithm describes an image object, from coarser structures to finer details, by the loci and sizes of the translated structuring elements which are included in the object. This algorithm provides a minimal redundancy shape representation. To evaluate this algorithm in the context of binary image coding, we propose two different techniques for encoding representative points issued from our shape decomposition algorithm. Comparative experimental results with two classical methods (Modified Huffman RLC and TUH code) and also a morphological method (discrete skeleton), expressed in terms of compression ratio, show the good performances of our approach.

Rémi Jeannot

Papers

Binary image representation and coding by a double-recursive morphological algorithm