Abstract: There is disclosed an image processing apparatus in which original image data are compressed by encoding to a smaller quantity, then the image processing is conducted in such compressed form, and thus processed data are released with a high resolving power and a satisfactory tonal rendition. In this manner highly advanced image processing can be achieved with a limited memory capacity.

Abstract: This invention has as its object to provide an image coding method which can efficiently encode image data by fully utilizing a two-dimensional correlation of an image. A block matching means searches for a block position corresponding to a minimum absolute value sum of differences of a pixel block to be encoded from already encoded pixel blocks. The searched block position information is encoded by an encoder, and the searched inter-block difference value is Huffman-encoded by another encoder. A code generator generates encoded data using these codes.

Abstract: There is provided an image encoding method in a facsimile apparatus or an image filing apparatus as an image communication apparatus. In this method, a color image signal which is expressed by a plurality of color component signals to be encoded is input, the input color image signal is converted into a bit stream signal, and the bit stream signal is encoded by prediction encoding. A parameter for the prediction encoding is changed in accordance with the color image signal to be encoded. The encoding operation is executed adaptively to the color image signal to be encoded. By virtue of bit stream converting the binary color signal, efficient encoding using the color correlation can be executed and an increase in data amount is prevented. By encoding the bit stream signal using a dynamic arithmetic code, a binary color image can be efficiently encoded.

Abstract: A binary image reducing method is so adapted that image reduction in which the occurrence of discontinuous lines is eliminated, is made possible even when there is a change in the reduction magnification of an image containing many lines of one-pixel width and characters or the like composed of line elements having a width of one to several pixels, such as an image created by a computer. First, an original image is subjected to enlargement processing by a micro-enlarging circuit, whereby the image is enlarged by 2.times.p (where, and the reduction ratio is p). Thereafter, 1/2 reduction processing, of the type which preserves fine lines, is executed by a 1/2 reducing circuit. As a result, it is possible to achieve a change in reduction at any desired magnification of 1/2-1 as well as preservation of fine lines in the reduced image obtained.

Abstract: There is disclosed a method for converting multi-level image data into binary image data and an apparatus therefor. An average density is calculated from the already binarized density of pixels positioned in a predetermined area around an object pixel, and the threshold value for binarization is set by adding a fixed bias value and varying dither signals to the average density, and the error generated in the binarization is distributed to the unbinarized pixels positioned behind. The addition of the fixed bias prevents formation of a spot-free white area in the vicinity of an edge or in the initial stage of processing, and the addition of dither signals prevents texture formation in the low density area.

Abstract: There is disclosed an image processing apparatus in which original image data are compressed by encoding to a smaller quantity, then the image processing is conducted in such compressed form, and thus processed data are released with a high resolving power and a satisfactory tonal rendition. In this manner highly advanced image processing can be achieved with a limited memory capacity.

Abstract: An image processing apparatus is provided which can shape codes and omit buffers at a decoding side as well as omit an image memory at an encoding side by providing code buffers for respective encoders. An image encoding apparatus for encoding image information in a hierarchical form includes encoders provided for respective hierarchies and code buffers provided after the respective encoders. Furthermore, it is possible to use a common code buffer memory for respective hierarchies at the encoding side. In such a case, by arranging so that a hierarchical tag can identify to which hierarchy a code belongs, a simplified encoding apparatus is provided.

Abstract: There is provided an image encoding method in a facsimile apparatus or an image filing apparatus as an image communication apparatus. In this method, a color image signal which is expressed by a plurality of color component signals to be encoded is input, the input color image signal is converted into a bit stream signal, and the bit stream signal is encoded by the prediction encoding. A parameter for the prediction encoding is changed in accordance with the color image signal to be encoded. The encoding operation is executed adaptively to the color image signal to be encoded. By bit stream converting the binary color signal, the efficient encoding using the color correlation can be executed and an increase in data amount is prevented. By encoding the bit stream signal by using a dynamic arithmetic code, a binary color image can be efficiently encoded.