Abstract: Image data of a pixel matrix are subjected to orthogonal transformation to coefficient data, which are then quantized with a first quantization table for character image and with a second quantization table for half-tone image. Image data are discriminated as character image data or half-tone image data according to the quantization data. The quantization data corresponding to the discrimination are subjected to entropy coding. Image data can be divided into first processing blocks of m*m pixel matrices and second processing blocks of M*M pixel matrices where M>m. A second processing block includes one first processing block and adjacent pixels. Image data in first and second processing blocks are subjected to orthogonal transformation to coefficient data. Coefficient data of the second processing block indicates whether the image is a character image, a dot image, or a half-tone image, permitting selection of an appropriate quantization table.

Abstract: In a data processor, in order to perform coding efficiently, image data of a prescribed pixel matrix is subjected to orthogonal transformation to coefficient data. Obtained coefficient data is quantized with a first quantization table for character image, and they are also quantized with a second quantization table for half-tone image. Then, the image data is discriminated to be a character image data or a half-tone image data according to the two quantization data. Then, quantization data in correspondence to the discrimination is subjected to entropy coding. In a different data processor, in order to discriminate a kind of image in a processing block fast and correctly, image data are divided into first processing blocks of m*m pixel matrices and second processing blocks of M*M pixel matrices wherein M>m. For example, m=8 and M=16. A second processing block includes one of first processing blocks and adjacent pixels around it.

Abstract: An image forming apparatus records an image on a recording medium after correcting a slant of the image according to a type of document sheet or an operating history of the image forming apparatus. Normally, a slant of the document sheet is corrected by bringing one edge of the sheet in contact with a document scale provided on a document platform. When the sheet is of thin paper or sheets of different sizes are mixed, an image signal obtained by scanning a document image is electrically processed so as to correct a slant of an image to be recorded. When the image signal is electrically processed so as to correct the slant of the image to be recorded, the correction of image slant may be based also on the operating history of the image forming apparatus, for example, the total number of sheets transported, the number of times a paper jam has occurred or the cumulative value of the slant angle of the image.

Abstract: When a jam occurs in outputting an image to a printer in a facsimile apparatus, it is displayed that the printer is in a state of trouble. If the printer trouble is not solved in a prescribed time period, that one group of original being printed is stored in a compressed data memory (not shown) as a re-recording file. When the trouble is solved, the data of that one group of original stored in the re-recording file is output to the printer. As a result, a facsimile apparatus capable of clarifying the destination of the printed received image data after an interruption can be provided.

Abstract: In a data processor, in order to discriminate the kind of image in a processing block quickly and correctly, image data is divided into first processing blocks of m*m pixel matrices and second processing blocks of M*M pixel matrices wherein M>m. The second processing block includes the data of the first processing block and adjacent pixels around it. Image data in the first and second processing blocks are subjected to orthogonal transform to generate coefficient data. The image type is discriminated as a character image, a dot image or a half-tone image according to the coefficient data of the second processing block and an appropriate quantization table is then selected. Having identified the appropriate quantization table based on analysis of second processing block, image data of the first processing block is quantized according to the thus selected quantization table and quantized data is thereby coded.

Abstract: The invention relates to an image reading apparatus for reading images of original documents by moving the original relative to a stationary image reader. A single image reader is used in a first embodiment. When reading the image of a first side, the single image reader is stationary at a first position to read the original. When reading the image of a second side, the single image reader is moved to a second position corresponding to the size of the original, and reads the image of the second side while said image reader is stationary at the second position. The image reading apparatus of the second embodiment uses a stationary first reader for reading a first side of an original, and a movable second image reader for reading a second side of an original. The image reading apparatus of the second embodiment changes the position of the image reader in accordance with the size of the original.

Abstract: An image forming apparatus records an image on a recording medium after correcting a slant of the image according to a type of document sheet or an operating history of the image forming apparatus. Normally, a slant of the document sheet is corrected by bringing one edge of the sheet in contact with a document scale provided on a document platform. When the sheet is of thin paper or sheets of different sizes are mixed, an image signal obtained by scanning a document image is electrically processed so as to correct a slant of an image to be recorded. When the image signal is electrically processed so as to correct the slant of the image to be recorded, the correction of image slant may be based also on the operating history of the image forming apparatus, for example, the total number of sheets transported, the number of times a paper jam has occurred or the cumulative value of the slant angle of the image.

Abstract: In the electronic sort of a digital copying machine, image data of a document consisting of a plurality of sheets are read and compressed to bi-level data in a memory. The compressed image data are recovered to multi-level data successively. When a plurality of copies of the document are produced, the recovery action is repeated by the number of the copies. In a facsimile machine combined with a digital copying machine, bi-level image data for the automatic reduction transmission are recovered first to multi-level image data, and the density of the multi-level image data is changed for the reduction. Then, the multi-level data are converted to bi-level data for facsimile transmission. In a digital two-color copying machine, multi-level image data of the second color of the two colors to be recorded later has to be synchronized to those of the other in correspondence to the delay of the recording time between the two colors.

Abstract: In data processing wherein image data are processed by dividing them into blocks, a chroma data W is obtained from the color difference data W.sub.R and W.sub.B, and the color difference data W.sub.R and W.sub.B are corrected according to an amplitude of the chroma data W. For example, if the chroma W is smaller than a prescribed threshold value, the color difference data W.sub.R and W.sub.B are set as zero. Then, the so-called block distortion can be prevented. The degree of the correction may depend on the amplitude of the chroma data W. On the other hand, DC coefficients of discrete cosine transform coefficients of adjacent blocks are compared with each other. When the DC coefficients are different from each other, block distortion occurs if they represent a same image. Then, if differences of DC coefficients of discrete cosine transform coefficients of adjacent blocks are small with each other, the DC coefficients are corrected to tend to have similar values.

Abstract: Additional data useful for the management of copies of a document for an image forming apparatus is embedded in a hard copy of the document. The additional data is embedded in an inherent image of a document as pixels arranged in a prescribed format, and, preferably, the size of the pixels is such as to not be easily recognized with the naked eye. The image data for embedding the additional data can be obtained by reading a document, or by receiving data sent from a computer or read from a floppy disk. Additional data embedded in a hard copy can be extracted from the image data on the hard copy, and the production of a copy according to the image data can be controlled according to the extracted additional data. For example, if the additional data means that the source of the hard copy is a secret document, copying thereof is allowed only for a legitimate user. Additional data generated for each copy is compiled and is used to manage copies of various sources systematically.

Abstract: In an image signal processing portion, the size of an original papersheet is detected, and image data is provided with respect to a memory unit. The size of a copy papersheet is detected using a detecting sensor, not shown. Data of an original image is read out by a CCD to be stored in an image memory. When printing is carried out based on the image data, the feeding directions and the sizes of the original papersheet and the copy papersheet are taken into consideration. When the feeding directions of the original and the copy papersheet are the same, only a variable-scale magnification processing portion is activated to carry out only a variable-scale magnification processing. When the feeding directions of the original papersheet and the copy papersheet are different, a rotation and a variable-scale magnification of an image signal are carried out by a rotation processing portion and the variable-scale magnification processing portion.

Abstract: A print head for reproducing a multi-level image is an provided. In the print head, a light-emitting array comprises a linear line of light-emitting elements. A D/A converter converts a multi-level image data to an analog signal, and an analog shift register shifts and latches the analog signals of a line received from the D/A converter. An analog latch register latches the analog signals held by the analog shift register. A driver controls the quantity of light of the light-emitting elements according to the analog signals latched by the analog latch register. In one embodiment, the print head includes a second analog shift register, an A/D converter a line memory and a divider which divides the image data by a signal from the line memory to produce corrected data which is provided to the driver to control driving of the light-emitting elements.

Abstract: In a shadow process mode, a scanner reads out an original with a first exposure lamp in a first scanning operation. The readout image data is stored in an image memory via an I/O control unit. In the second scanning operation, the scanner reads out the original with a second exposure lamp having an illumination direction different from that of the first exposure lamp. The image data read out in the second scanning operation and the data stored in the image memory are subtracted for each pixel by a subtractor. The difference thereof is compared with a predetermined value in a comparator. The compared result is output to a selector, whereby a desired image data is provided to a printer processing unit via the I/O control unit.

Abstract: In data processing wherein image data are processed by dividing them into blocks, a chroma data W is obtained from the color difference data W.sub.R and W.sub.B, and the color difference data W.sub.R and W.sub.B are corrected according to an amplitude of the chroma data W. For example, if the chroma W is smaller than a prescribed threshold value, the color difference data W.sub.R and W.sub.B are set as zero. Then, the so-called block distortion can be prevented. The degree of the correction may depend on the amplitude of the chroma data W. On the other hand, DC coefficients of discrete cosine transform coefficients of adjacent blocks are compared with each other. When the DC coefficients are different from each other, block distortion occurs if they represent a same image. Then, if differences of DC coefficients of discrete cosine transform coefficients of adjacent blocks are small with each other, the DC coefficients are corrected to tend to have similar values.

Abstract: An image reading apparatus provided with a document feeder, and in which a plurality of originals are set on a platen glass and read in a single reading operation to obtain image data. The obtained image data are stored in an image memory. The number of originals which can be placed on the platen glass varies in accordance with the size of the originals to maximize the number of originals to be placed on the platen glass.

Abstract: In a data processor, image data of a pixel matrix is subjected to orthogonal transformation to coefficient data, the coefficient data is quantized with a first quantization table for character image and a second quantization table for half-tone image, and the image data is discriminated to be character image data or half-tone image data according to the quantization data. The selected data is then coded. In another processor, image data are divided into first and second processing blocks of m*m and M*M pixel matrices wherein M>m and the second processing block includes one of first processing blocks and adjacent pixels. Image data in a first and second processing block are subjected to orthogonal transformation to coefficient data.

Abstract: An image data processing system includes a still video camera having a detachable storing medium for storing an image data, and a digital image forming apparatus in which an image of an original document is read by an image sensor to generate an image data, and the image is formed on a paper with electrophotographic process based on the image data. Also, the image data is processed in the image forming apparatus to be stored on the storing medium of the still video camera loaded detachably from the image forming apparatus.

Abstract: An image forming apparatus comprises a document transport mechanism for transporting a document to a reading station, an image reading unit for reading an image of the document at the reading station and for outputting image data descriptive of the image of the document, a image forming unit for performing an image formation based on the image data, a memory for storing the image data, a data writing unit for transferring and writing the image data to the memory, and a data reading unit for reading the image data from the storage means in readiness for a transfer of the image data to the image forming unit. A control unit is provided for controlling a data write operation, performed by the data writing unit, and a data read operation, performed by the data reading unit, so as to be accomplished independently and in parallel relation with each other.

Abstract: An image reading apparatus for reading an image of an original while transporting the original from an original tray to an image reading position. When an original once read has to be read again due to some trouble, the original is automatically transported to an original tray provided upstream of the reading position so that the original can be automatically read again without operator intervention.

Abstract: The invention relates to an image reading apparatus for reading images of original documents by moving the original relative to a stationary image reader. A single image reader is used in a first embodiment. When reading the image of a first side, the single image reader is stationary at a first position to read the original. When reading the image of a second side, the single image reader is moved to a second position corresponding to the size of the original, and reads the image of the second side while said image reader is stationary at the second position. The image reading apparatus of the second embodiment uses a stationary first reader for reading a first side of an original, and movable second image reader for reading a second side of an original. The image reading apparatus of the second embodiment changes the positions of the image reader in accordance with the size of the original.