Abstract: An image processing apparatus changes a pixel value of a pixel of interest in image data to be processed by a predetermined condition concerning a spatial frequency to generate corrected image data, and performs a predetermined coding process with regard to the corrected image data to generate coded data. Thus, processor load in the coding process can be reduced.

Abstract: An encoding device includes a binary image generation unit that generates at least two binary images from a multivalued image by applying different methods, a check image generation unit that generates a check image based on the plural binary images generated by the binary image generation unit, and a code generation unit that generates coded data by encoding at least one of the binary images generated by the binary image generation unit and the check image generated by the check image generation unit by using different methods.

Abstract: A coding apparatus includes a color space conversion unit that converts input image data into image data which is represented in another color space, a gradation changing unit that changes gradation of the input image data, based on the converted image data, and a predictive coding unit that performs predictive coding on the image data subjected to the gradation change.

Abstract: An encoding device has a shape encoding unit and a pattern encoding unit. The shape encoding unit encodes a shape of an image element. The pattern encoding unit encodes a binary pattern of the image element and the shape of the image element is related to the binary pattern of the image element.

Abstract: A coding apparatus includes a shape coding section and a density coding section. The shape coding section codes shape information of an image element contained in an input image. The density coding section codes density information of the image element contained in the input image, with using a density dictionary including a binary pattern representing an image density and first identification information identifying the binary pattern in association with each other.

Abstract: A pixel value change processing section corrects the value of a current pixel in an input image so that the size of a code produced by a coding processing section is reduced, and outputs a changed pixel value. When predictive coding is employed, the pixel value change processing section outputs the same pixel value as that which is predicted by a predictor. When arithmetic coding is employed, the pixel value change processing section outputs a pixel value at which a dominant symbol is obtained in the arithmetic coding. The coding processing section produces a code from the changed pixel value 310. The pixel value change processing section produces an error value between the current pixel value and the changed pixel value. An error distribution processing section produces an error distribution value from the error value and adds the error distribution value to the pixel value of the input image.

Abstract: Filtering for enhancing the reversible compression rate is performed for image data as preprocessing of compression processing. For image processing after the filtering, repeating of compression and decompression according to the reversible compression technique corresponding to the filtering is allowed. As the filtering and reversible compression processing are performed, a sufficient compression ratio is provided and accumulation of image quality degradation by repeating compression and decompression is prevented.

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: A printer scales up a pixel group to match the resolution of an input image with that of an output image. Further, if it is necessary to compress and retain image data during image formation processing, the printer performs preprocessing forming a part of compression processing and then performs scale-up processing of pixel data, thereby making it possible to decrease the processing load of the preprocessing and further provide a high compression ratio.

Abstract: An image processing apparatus changes a pixel value of a pixel of interest in image data to be processed by a predetermined condition concerning a spatial frequency to generate corrected image data, and performs a predetermined coding process with regard to the corrected image data to generate coded data. Thus, processor load in the coding process can be reduced.

Abstract: A pixel value change processing section corrects the value of a current pixel in an input image so that the size of a code produced by a coding processing section is reduced, and outputs a changed pixel value. When predictive coding is employed, the pixel value change processing section outputs the same pixel value as that which is predicted by a predictor. When arithmetic coding is employed, the pixel value change processing section outputs a pixel value at which a dominant symbol is obtained in the arithmetic coding. The coding processing section produces a code from the changed pixel value 310. The pixel value change processing section produces an error value between the current pixel value and the changed pixel value. An error distribution processing section produces an error distribution value from the error value and adds the error distribution value to the pixel value of the input image.

Abstract: An index signal and a delta signal are generated from an input pixel value, and then, inputted to an input buffer by every predetermined pixel to be processed. A controlling unit compares the index signal in the input buffer with a tag (index signal) in a coefficient cache. When they coinside with each other, the controlling unit reads out the corresponding coefficient from the coefficient cache and supplies the same to an interpolating unit. The interpolating unit simultaneously receives the delta signal and supplies the keeping color data to an output buffer. Thereafter, the interpolating unit accesses to the coefficient storing memory by using an index signal that does not coinside with either one of cache-tag (index signal) to obtain a coefficient, and similarly, interpolatively generates color data. Data of converted color is outputted from the output buffer in the order of inputting the pixel.

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.