Method, medium and apparatus effectively compressing and restoring edge position images

An image compression method comprising:

• (a) predicting values of pixels positioned at a predetermined directional edge among pixels constructing a block having a predetermined size in a current image, using values of neighbor pixels of the pixels positioned at the predetermined directional edge;
• (b) repeating operation (a) with respect to each remaining directional edge except for the predetermined directional edge, among a plurality of directional edges;
• (c) selecting an edge mode in which the difference between the values predicted in operations (a) and (b) and actual values of the pixels positioned at the predetermined directional edge is a minimum;
• (d) outputting edge mode data indicating the selected edge mode, instead of the predicted values corresponding to the selected edge mode, thereby compressing the values of the pixels positioned at the predetermined directional edge.

An image compression method comprising:

• (a) compressing values of pixels constructing a block having a predetermined size in a current image, according to a plurality of predetermined image compression methods;
• (b) predicting values of pixels positioned at a predetermined directional edge, among the pixels constructing the block, using values of neighbor pixels of the pixels positioned at the predetermined directional edge, thereby compressing the values of the pixels positioned at the predetermined directional edge;
• (c) selecting a mode from among a plurality of modes corresponding to the plurality of predetermined image compression methods and an image compression method used in operation (b), on the basis of the results compressed in operations (a) and (b);
• and
• (d) generating a bit stream packet including mode data indicating the selected mode and compressed data corresponding to the selected mode.

An image restoring method comprising:

• (a) extracting mode data and compressed data of a block having a predetermined size in a current image, from a bit stream packet;
• (b) recognizing a mode corresponding to an image compression method of a plurality of image compression methods, from the mode data;
• and
• (c) predicting values of pixels positioned at a directional edge indicated by the recognized mode, among pixels constructing the block, using values of neighbor pixels of the pixels positioned at the directional edge, according to the recognized mode, thereby restoring the values of the pixels positioned at the directional edge.