Method and apparatus for encoding an image signal having an object by using an extension-interpolation technique

A method for converting a processing block included in an image frame signal having an object to an extended processing block, wherein the processing block consisting of N.times.N pixels which are classified into object pixels and background pixels, N being a positive integer, the object pixels being located within the object and the background pixels being located outside the object, comprises the steps of:

• (A) deciding either a horizontal or a vertical extension which has a priority based on a shape of the object pixels in the processing block;
• (B) in case the horizontal extension has the priority, selecting a plurality of object rows, each of the object rows being a row of the processing block having at least one object pixels, and for each of the object rows, providing a first vector, each element of the first vector being a value of each object pixel included in said each object row, and in case the vertical extension has the priority, selecting a plurality of object columns, each of the object columns being a column of the processing block having at least one object pixels, and for each of the object columns, providing a first vector, each element of the first vector being a value of each object pixel included in said each object column, to thereby provide L first vectors, L being an integer ranging from 0 to N and denoting a number of object rows or columns;
• (C) converting each of the first vectors to an extended first vector by using a linear interpolation, to thereby provide L extended first vectors, each of the L extended first vectors having N elements;
• (D) in case the horizontal extension has the priority, providing a first extended processing block including L rows, each row having N pixels whose values are elements of each of the extended first vector and, for each column of the first extended processing block, providing an L-dimensional second vector, elements of the second vector being values of pixels included in said each column of the first extended block, and in case the vertical extension has the priority, providing a first extended processing block including L columns, each column having N pixels whose values are elements of each of the extended first vectors and, for each row of the first extended processing block, providing an L-dimensional second vector, elements of the second vector being values of pixels included in said each row of the first extended block;
• (E) converting each of the second vectors to an extended second vector by using a linear interpolation, to thereby provide N extended second vectors, each of the N extended second vectors having N elements;
• and
• (F) in case the horizontal extension has the priority, providing the extended processing block including N columns, each column having N pixels whose values are elements of each of the extended second vectors, and in case the vertical extension has the priority, providing the extended processing block including N rows, each row having N pixels whose values are elements of each of the extended second vectors.

A method for converting a processing block included in an image frame signal having an object to an extended processing block, wherein the processing block consisting of N.times.N pixels which are classified into object pixels and background pixels, N being a positive integer, the object pixels being located within the object and the background pixels being located outside the object, comprises the steps of:

• (A) selecting L rows of the processing block, each of the L rows having at least one object pixels, L being an integer ranging from 0 to N;
• (B) for each row selected at step (A), determining M representing a number of object pixels included in said each row and providing a first vector, each element of the first vector being a value of each of the M object pixels, M being an integer ranging from 1 to N;
• (C) for each first vector, selecting an extension matrix among a multiplicity of predetermined extension matrices, based on the M and N values and multiplying the selected extension matrix to the first vector to provide an extended first vector;
• (D) providing a first extended processing block which includes L rows, each row having N pixels whose values are elements of each of the extended first vectors;
• (E) for each column of the first extended processing block, providing an L-dimensional second vector, elements of the second vector being values of pixels included in said each column of the first extended processing block;
• (F) selecting an extension matrix among a multiplicity of the predetermined extension matrices based on the L and N values;
• and
• (G) multiplying the extension matrix selected at step (F) to each of the second vectors, to provide N extended second vectors and to thereby provide the extended processing block which includes N columns, each column having N pixels whose values are elements of each of the extended second vectors.

An apparatus for encoding an image frame signal having an object, wherein the image frame signal consists of object pixels and background pixels, the object pixels being located within the object and the background pixels being located outside the object, said apparatus including:

• (A) means for detecting a boundary of the object included in the image frame to generate a contour signal providing boundary information for tracing the object boundary;
• (B) means for encoding the contour signal to generate a first encoded image frame signal;
• (C) means for dividing the image frame into a plurality of processing blocks, each of the processing blocks having N .times.N pixels, N being a positive integer;
• (D) means for generating a control signal indicating whether or not a part of the object boundary exists in each of the processing blocks;
• (E) means for dividing the processing blocks to a first and a second sets of processing blocks in response to the control signal, wherein a part of the object boundary exists in each of the processing blocks of the first set;
• (F) means for converting each processing block of the first set to an extended processing block;
• (G) means for encoding the extended processing blocks or the second set of processing blocks, to thereby produce a second encoded image frame signal;
• and
• (H) means for formatting the first and the second encoded image signals,
• wherein said means for converting comprises:
• (F1) means for deciding either a horizontal or a vertical extension which has a priority based on a shape of the object pixels in each processing block of the first set;
• (F2) means, in case the horizontal extension has the priority, for selecting a plurality of object rows, each of the object rows being a row of the processing block having at least one object pixels, and for each of the object rows, providing a first vector, each element of the first vector being a value of each object pixel included in said each object row, and in case the vertical extension has the priority, for selecting a plurality of object columns, each of the object columns being a column of the processing block having at least one object pixels, and for each of the object columns, providing a first vector, each element of the first vector being a value of each object pixel included in said each object column, to thereby provide L first vectors, L being an integer ranging from 0 to N and denoting a number of object rows or object columns;
• (F3) means, for each first vector, for selecting an extension matrix among a multiplicity of predetermined extension matrices, based on a number of elements in said first vector and N, and multiplying the selected extension matrix to said each first vector, to thereby provide L extended first vectors, each of the L extended first vectors having N elements;
• (F4) means, in case the horizontal extension has the priority, for providing a first extended processing block including L rows, each row having N pixels whose values are elements of each of the extended first vectors and, for each column of the first extended processing block, for providing an L-dimensional second vector, elements of the second vector being values of pixels included in said each column of the first extended block, and in case the vertical extension has the priority, for providing a first extended processing block including L columns, each column having N pixels whose values are elements of each of the extended first vectors, and, for each row of the first extended processing block, for providing an L-dimensional second vector, elements of the second vector being values of pixels included in said each row of the first extended block;
• (F5) means for choosing an extension matrix among a multiplicity of the predetermined extension matrices based on the L and the N values;
• (F6) means for multiplying the extension matrix chosen at means for choosing, to each of the second vectors, to thereby provide N extended second vectors, each of the N extended second vectors having N elements;
• and
• (F7) means, in case the horizontal extension has the priority, for providing the extended processing block including N columns, each column having N pixels whose values are elements of each of the extended second vectors, and in case the vertical extension has the priority, for providing the extended processing block including N rows, each row having N pixels whose values are elements of each of the extended second vectors.