Abstract: An image processing apparatus compresses multi-level images created by a computer or the like at a high compression rate. To achieve this, the image processing apparatus includes an ADCT compression unit for compressing input multilevel image data for every block of data (the blocks having a predetermined size) by an irreversible compression method, and a reversible compression unit for compressing the input multilevel image data for every block by a reversible compression method. Selection between output data from the two compression units on the basis of data having a predetermined level and compressed by the reversible compression unit.

Abstract: When image data is compressed in units of blocks, if a compressed data amount D obtained by reversibly compressing a block, and a predetermined value L satisfy D.ltoreq.L, the block is reversibly compressed; if they satisfy D>L, the block is irreversibly compressed, so that computer-created image data is compressed while preventing deterioration of image quality, and a gradation image or a natural image is efficiently compressed. When a pixel of interest has the same value as color data (C.sub.1) of the immediately preceding pixel, the shortest code `1` is output; when the pixel of interest has the same value as color data (C.sub.2) of a pixel, which has color data different from C.sub.1, and appears latest, the second shortest code `01` is output; when the pixel of interest has the same value as color data (C.sub.3) of a pixel, which has color data different from C.sub.1 and C.sub.2, and appears latest, the third shortest code `001` is output; when the pixel of interest has color data different from C.

Abstract: Use is made of a neural network in order to restore a binary image to an original multi-level image, by way of example. Using the neural network makes it possible to raise the accuracy of restoration and the speed of processing.

Abstract: A first comparator compares pixel data outputted by a pixel-data generating unit with an immediately preceding item of pixel data that has been latched by a first latch. The result of comparison is delivered to a first memory unit. If the result of comparison is that the two compared items of pixel data do not agree, a second comparator compares the pixel data outputted by the pixel-data generating unit with pixel data latched by a second latch. The result of this comparison is delivered to a second memory unit. If the result of the comparison performed by the second comparator is that the two compared items of pixel data do not agree, the pixel data from the generating unit is stored in a third memory unit. When the pixel data latched by the first latch does not agree with this pixel data, the content latched by the second latch is updated to the content latched by the first latch and the content latched by the first latch is updated to this pixel data.

Abstract: An image processing apparatus initially stores variable length codes corresponding to a significant frequency component, and variable length codes corresponding to a less significant frequency component If while storing the variable length codes into the storage means, it is detected that the storage means is full (with variable length codes), the control means makes room for the storage of further variable length codes corresponding to the more significant frequency component by canceling variable length codes stored in the storage means which correspond to the frequency component.

Abstract: The invention concerns a color image communication apparatus, which comprises scan conversion means for converting n-level image data received in a raster scan system via a communication line to data in a shuttle scan system, multi-level conversion means for converting color n-level data obtained from the scan conversion means for multi-level data, and color conversion means for converting color characteristics of multi-level data obtained from the multi-level conversion means from color characteristics for a communication line to color characteristics of output color recording means.

Abstract: A color image communication apparatus can switch between a copy mode and a communication mode. In the communication mode, color space standardization conversion of objective color image data is performed, while in the copying mode, color space standardization conversion of the objective image data is not performed.

Abstract: Use is made of a neural network in order to restore a binary image to an original multi-level image, by way of example. Using the neural network makes it possible to raise the accuracy of restoration and the speed of processing.

Abstract: It is provided an image communication apparatus which comprises multi-level generation section for generating multi-level data from received image data, color conversion section for color-converting the multi-level data from the multi-level generation section, and setting section for setting a single color mode, in which the received image data is dealt with as single color data irrespective of the color conversion section, when it is determined by communication protocol that the communication mode is the single color mode, so as to ensure satisfactory communication even with a single color image.

Abstract: Disclosed is an image processing apparatus having an input device for inputting binary image data comprising a plurality of pixels which include a pixel of interest that is to be subjected to multivalued conversion, the plurality of pixels being contained in an area that is asymmetrical with respect to the position of the pixel of interest, and an multivalued converting device for executing processing, by a neural network, to restore the input binary image data to multivalued image data for the pixel of interest, whereby multivalued image data is estimated from binarized image data. It is possible to reduce the number of pixels referred to in arithmetic operations performed in the neural network.