Abstract: A method for color correcting an original halftone bitmap image by a predefined color correction function to produce a color corrected halftone bitmap image comprising: providing an original halftone bitmap image; estimating the dot area percentage of the original halftone bitmap image in a set of sub-image blocks; calculating an aim dot area percentage, based on a predefined color correction function, for each sub-image block in the original halftone bitmap image, calculating the number of halftone bitmap image pixels to convert to on or off states to produce a modified original halftone bitmap image that has the aim dot area percentage where said value is designated by N, for each sub-image block in the original halftone bitmap image, and converting N pixels in the original halftone bitmap image to either on or off states depending on whether the aim dot area percentage is greater or less than the dot area percentage of the original halftone bitmap image respectively, for each sub-image block in the origina

Abstract: An image forming apparatus comprises an edge detection means for detecting an edge in image data, a thinning judgment unit (11) for judging whether or not a thinning process in the image data should be performed, and an edge density conversion unit (12) for receiving a discrimination signal from said thinning judgment unit (11) to perform density conversion of a pixel which is judged to be subject to the thinning process.

Abstract: A printhead controller controls printing of a page by at least one printhead. The printhead controller is connected, in use, via a data communications link to a printer controller for receiving data, in a compressed format relating to the page to be printed, the data including a page description comprising a bi-level black layer and a contone color layer. The printhead controller includes a first decoder for expanding compressed data relating to the bi-level black layer and a second decoder for expanding compressed data relating to the contone color layer. The first and second decoders are arranged in parallel. First and second temporary storage devices are provided for storing the expanded data from the first and second decoders, respectively. A data manipulating unit manipulates the data output from these temporary storage devices to be fed to the printhead.

Abstract: An image processing apparatus includes an edge detecting unit which identifies an area of given image data as a gradation sequence area and a character/line art area and which outputs edge information of the character/line art, a level converting unit which generates a strength modulation signal so as to emphasize an edge of the character/line art area, a laser driver which outputs a laser drive signal in order to form a picture dot larger than a standard size in response to the strength modulation signal. Further, according to the present invention, it is possible to print an image with emphasizing an edge portion of a character/line art by a laser printer.

Abstract: An image processing apparatus includes an edge amount calculating device configured to calculate edge amounts of an image in a plurality of directions for each of a plurality of frequency bands of the image. A character edge area determination device determines, based on the calculated edge amounts, whether or not a selected picture element of the image is of a character edge area. A sharpness control device corrects a frequency characteristic of the image by performing a first correction to the edge amounts when the selected picture element is determined to be of a character edge area by the character edge area determining device, and by performing a second correction to the edge amounts when the selected picture element is determined not to be of a character edge area by the character edge area determining device.

Abstract: An image processing apparatus includes a first filtering process device configured to perform a predetermined space frequency characteristic conversion process to input image data having multiple-level gradation. A conversion process device performs a gradation characteristic conversion process to an output result of the first filtering process device. A second filtering process device performs a predetermined space frequency characteristic conversion process to an output result of the conversion process device. A halftone processing device performs a quasi-gradation processing to an output result of the second filtering process device.

Abstract: A method and structure for determining overall lightness contrast of an image includes extracting pixel values from the image, calculating an image edge contrast based on the pixel values, calculating an area contrast based on the pixel values, calculating image range based on the pixel values, calculating relative average lightness based on the pixel values, and calculating the overall lightness contrast of the image by combining the edge contrast, the image range, the area contrast and the relative average lightness.

Abstract: An imaging apparatus includes an input that receives a stream of image pixels such as high addressable bits, multiple bits per pixel or binary image bits representing an input image and a processor that processes and directs signals to an LED bar that selectively exposes areas of a photoreceptor. The exposed areas of the photoreceptor form a latent image, controlled by the processor, of areas of varied exposure based on surrounding pixels. The processor examines the pixels to determine an image structure beneficially adaptable to varied exposure and selects a pixel for varied exposure, such as increased or decreased exposure or altered timing to apply the pixel.

Abstract: An image processing method and apparatus for improving both gradation and resolution in a screening process. The apparatus comprises an image memory for storing multi-valued image data in pixel units; a pixel data acquiring portion for acquiring image pixel data from the memory; a threshold value matrix constituted by a density area by which dots of a high number of lines are produced and another density area by which dots of a low number of lines are produced; a threshold value data acquiring portion for acquiring from the matrix threshold value data corresponding to image data acquired by the pixel data acquiring portion based upon the image data address; and a comparator for comparing the acquired image data with the acquired threshold value data to thereby output a consequent binary signal.