Abstract: An image coding apparatus includes an approximating element having plural different prediction techniques to approximate, a value of a target pixel to be coded with reference to values of peripheral pixels surrounding the target pixel; a holding element which holds information about ranks of the prediction techniques, the ranks obtained upon processing of the pixel preceding the target pixel; a determining element computing an error between each of approximate values obtained by the prediction techniques and that of the target pixel, selecting one of the prediction techniques for the target pixel based on the computer error, and performing the selection by preferentially referencing the rank information if the error is within a predetermined tolerance; and a coding element which codes the value of the target pixel using the approximate value obtained by the selected prediction technique.

Abstract: Images are to be efficiently and easily encoded while suppressing block distortion and pseudo-contour generation. A quantization characteristics determining unit receives pixel values from a pixel value input unit, measures the length S of the consecutive occurrence of the same pixel values in connection with a pixel to be encoded and the pixel value differences D, and determines quantization characteristics n with reference to the result of sensory evaluation. A quantization/inverse quantization unit quantizes pixel values to be inputted with the quantization characteristics n, and further inverse quantizes them to reduce the number of gray-scale levels. The output pixel values of the quantization/inverse quantization unit are encoded and outputted by an entropy encoding unit.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the basis of the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: An image processing system that utilizes a CPU is provided. In the image processing system, image data to be processed is separated into plural image data elements, using predetermined requirements. At least one of the image data elements is selected. The selected image data element is subjected to pre-processing including orthogonal transform and quantization to create intermediate data. In order to create compressed data, both the intermediate data and an unselected image data element in the selection are subjected to entropy encoding.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the basis of the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: In a tandem-type full color printer, to print monochromatic image data the resolution of which is high and the processing load of which is high at high speed and at a low cost, the operation of each component is required as follows. If a monochromatic image is printed, MB images acquired by dividing the monochromatic image by an image processor are sequentially sent to the respective image compressors for YMCK. Four image compressors are operated in parallel and the compressed data of MB images is stored in an image storage. After the data of all MB images required for an output image is stored, an MB image controller operates the respective image decompressors for YMCK in parallel and sends the stored data to the image decompressors. The decompressed MB images are coupled to one image data in an image coupler and are sent to a print unit.

Abstract: An image processing device that executes high speed overwriting of an input image with one or more partial images. A processing prediction unit judges whether overwriting is completed on all the partial images held in a small area buffer. If overwriting is completed, the overwritten partial image is compressed by an encoding unit, and the coded image is stored in a compact page memory. If overwriting is not completed, the uncompressed partial image is stored in the compact page memory. The uncompressed partial image is read from the compact page memory and is fed back to the overwriting unit through an output switch unit. The coded image stored in the compact page memory is sent to a decoding unit through the output switch unit, and is decoded to be outputted as an output image.

Abstract: An image processing apparatus for overwriting image data at a low cost and high speed. An image input unit sequentially inputs partial data of an image data. An overwriting unit overwrites a non-coded partial data stored in a compressed page memory with the input partial image data and stores the result in a small area buffer. A process prediction unit analyzes a plurality of image data that are objects of an overwriting process, and predicts whether further overwriting is performed. When it is predicted that no further overwriting is performed, the partial image data is coded in a coder and updated in the compressed page memory. When it is predicted that a further overwriting is performed, the non-coded image data is updated in the compressed page memory. When the overwriting process of every partial image data of all of the image data is complete, the overwritten image data is stored as code data in the compressed page memory.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the basis of the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the basis of the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: The present invention presents an image processing apparatus that performs rotation, enlargement, reduction, clipping or overlapping processing of images at high speed using low capacity memories instead of page memories and without the need to read image data in repetition. A first band data storing element receives input image data line by line and stores it as local data. The local data stored in the first band data storing element is transformed by local data transforming element and then stored in a transformed data storing element. The local data is then read in the order it is to be output and stored in a second band data storing element. An image output element then outputs the local data as an output image.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the basis of the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: An input image is subjected to transform by a DCT transforming unit 20. A coefficient analyzing unit 30 compares a predetermined coefficient and coefficient data 120, and obtains low-frequency image data 150 of the input image by a high-frequency coefficient masking unit 50 and an inverse DCT unit 60 on the basis of a result of that comparison. A pixel subsampling unit 70 receives this low-frequency image data 150, and generates a subsampled image on the basis of the aforementioned result of comparison. The subsampled image and coefficient information are transmitted to a decoding side. A decoding apparatus decodes an image on the basis of the subsampled image and the coefficient information.

Abstract: The present invention presents an image processing apparatus that performs rotation, enlargement, reduction, clipping or overlapping processing of images at high speed using low capacity memories instead of page memories and without the need to read image data in repetition. A first band data storing element receives input image data line by line and stores it as local data. The local data stored in the first band data storing element is transformed by local data transforming element and then stored in a transformed data storing element. The local data is then read in the order it is to be output and stored in a second band data storing element. An image output element then outputs the local data as an output image.

Abstract: An image coding apparatus includes an approximating element which has plural different prediction techniques to approximate, in input image data, a value of a target pixel to be coded with reference to values of peripheral pixels surrounding the target pixel, a holding element which holds information about ranks of the prediction techniques, the ranks being obtained upon processing of the pixel preceding the target pixel, a determining element which computes an error between each of approximate values obtained by the prediction techniques and the value of the target pixel, and which selects one of the prediction techniques for the target pixel based on the computed error, the determining element performing the selection by preferentially referencing the rank information held in the holding element if the error is within a predetermined tolerance, and a coding element which codes the value of the target pixel using the approximate value obtained by the prediction technique selected by the determining element.

Abstract: An image processing apparatus and method rotates an image at any angle during frequency transform of image coding or image decoding. A basis calculator calculates transform bases according to a rotation angle parameter received from a parameter input unit, and outputs the calculated transform bases to a transform unit. A coordinate calculator calculates input block coordinates according to a rotation parameter, and outputs the calculated input block coordinates to an image input unit. The image input unit extracts an input image block from an input image in accordance with the input block coordinates, and outputs the extracted input image block to a transform unit. The transform unit transforms the input image block by using the transform bases, and outputs transform coefficients to an entropy encoder. The entropy encoder performs entropy coding of the transform coefficients, and outputs code data to an image output unit. Inverse processes are performed for decoding.

Abstract: In an image reading method, an image of an original document is read at a plurality of positions within one period in a manner that the focal position spaced a specific distance apart from the surface of the original document is periodically varied while being moved in the slow scan direction. The plurality of read positions during one period are synchronized every period. In-focus image data is detected from the image data read out during each period. Other image data than the detected in-focus image data during one period is replaced with the in-focus image data. Alternatively, blur of other image data than the detected in-focus image data during one period is corrected on the basis of the in-focus image data. An image reader based on the image reading method is also disclosed.