Abstract: An image processing apparatus for expanding given compressed image data in combination with other compressed image data, provided with a retaining device which retains, at the successive expansions of the compressed data, information relative to the development of a certain area until the data development of an area next to the above-mentioned certain area.

Abstract: A window of n.times.m dot is spread over binarized color image data in an original image in order to multi-levelcode the binary data for various image processes with respect to the multi-level-coded data. A binary window is re-arranged to determine the number of dots to be printed within the window for re-arrangement of the dots so as to correspond to the dot positions in the original image. When the number of dots to be printed is within the number of dots in the original image, the dots are rearranged so as to correspond to the dot positions in the original image, while on the contrary, when the number of dots to be printed is increased or decreased, the number of dots is accordingly increased or decreased based on a table, in which the priority of dot arrangement is provided.

Abstract: According to this invention, when n-value image data is transmitted, data associated with its compression method is transmitted to a reception-side apparatus, so that the reception-side apparatus can perform proper image processing. More specifically, there is disclosed an image transmission method having the following advantages. That is, when a reception-side apparatus can select one of a plurality of image processing methods, it selects a processing method matching with an n-value compression method, and properly reproduces an m-value image.

Abstract: A color image processor inputs the color image data of one color-separated picture element, weights the input color image data, reduces the amount of information of the weighted color image data and outputs the reduced color image data.

Abstract: When image data binarized by a density-preserving type multilevel-coding method is to be recovered to multilevel image data, the size of a scanning window which includes as a central pixel point a pixel point to be subjected to multilevel coding is varied and the sums of data values of the binarized image data contained in the scanning windows corresponding to individual window sizes are sequentially calculated in the order of window size. If the sum of the binarized image data value reaches a predetermined threshold for each scanning window size, this window size is determined as a scanning window size for multilevel coding, and multilevel coding is executed. With this process, an optimum window size is determined which is suitable for use in effecting multilevel-coding with high image quality. Since multilevel coding employing the optimum window size is performed, multilevel coding with high image quality and high resolution is enabled.