Abstract: A halftoning apparatus free of the occurrence of moiré and other artifacts under a simple technique. In the apparatus, the estimating section calculates the pixel value of the noteworthy pixel, which is to be converted into a binary value, based on other pixel values than that of the noteworthy pixel, and the binarizing section converts the multilevel value of the noteworthy pixel into a binary value.

Abstract: When input N-bit multi-valued image information having density information is converted into M-bit (N?M) image information and the converted image information is output, information (S signal) indicating whether or not an image conversion process is executed for one line including a pixel of interest of the multi-valued image information is generated on the basis of the multi-valued image information. Only when the S signal indicating that the image conversion process is to be skipped successively appears for a number of times equal to or larger than “the number of lines required for the process”+1, the control is made to forcibly set the processing result of the image conversion process to be a predetermined value, and to inhibit execution of the image conversion process for one line including the pixel of interest of the multi-valued image data.

Abstract: There is provided an image processing apparatus that can reduce the overlap of dots to thereby enable achievement of favorable visual characteristics, and reduce the amount of pseudo outlines in half tone and reduce the quantity of inks to be shot to thereby suppress an increase in the running cost. When performing the error diffusion on a first density component of the plurality of density components, a threshold to be used for the error diffusion is determined based on a density value of at least one second density component of the plurality of density components. The error diffusion on the first density component is executed based on the determined threshold. A result of the executed error diffusion is outputted.

Abstract: The present invention relates to an image processing method using the error diffusion method to prevent jumps in a highlight part and darkening in a shadow part at high resolution. The image processing method comprises a step of calculating an average value of density values of N×M (N, M>1) pixels, a step of adding the average value and a diffused quantization error value, a step of quantizing the addition result with a predetermined number of tones, a step of selecting a quantization pattern corresponding to the quantization result, and a step of calculating the diffused quantization error value from the quantization error. The error diffusion algorithm has flexibility in outputting dots. In other words, error diffusion processing is performed in N×M pixel units, and a plurality of quantization patterns are provided, and a quantization pattern is selected based on the quantization result.

Abstract: An apparatus and a method for generating high-quality binary image are provided. An input unit inputs a binary image as a multi-valued image. A halftone dot image area map creating unit searches for a halftone dot image area that may be in the multi-valued image and creates a halftone dot image area map. A line drawing/character area map creating unit searches for a line drawing/character image area that may be in the multi-valued image and creates a line drawing/character image area map. A halftone dot image binarizing unit binarizes an input image corresponding to the halftone dot image area map while suppressing input read error that may occur when said input unit inputs the binary image, and generates a binarized halftone dot image. A line drawing/character smoothing unit smoothes a jaggy contained in an input image corresponding to the line drawing/character area map, and generates a binarized line drawing/character image.

Abstract: An image data of M-gradations in a pixel is converted into multivalued image data of N-gradations (M>N>2) in a pixel. A remarked pixel converted into the multivalued data is determined whether to be a predetermined gradation TJ (N>TJ>2) in which a tone jump occurs. When the remarked pixel converted into the multivalued data is determined to be the predetermined gradation TJ, it is determined whether a pixel of the predetermined gradation TJ exists in pixels being adjacent to the remarked pixel. When the pixel of the predetermined gradation exists, the gradation of the remarked pixel is changed to the gradation other than the predetermined gradation so as to prevent the tone jump, and an average density after multivalued image data conversion is preserved.

Abstract: An image processing method of quantizing multi-tone image data by an error diffusion method, includes the steps of a) detecting change of the image data; and b) oscillating cyclically in image space a threshold for the quantization in an oscillation range controlled according to the detection result of the step a).

Abstract: An image forming method includes the steps of a) multi-level quantizing a multi-tone image by an error diffusion method, and b) representing each pixel of the thus-quantized image having a quantized level higher than 0 using a dot which is larger as the quantized level thereof is higher. Occurrence of dots having a specific size is repressed in a specific shade region relating to the dots.

Abstract: Image processing apparatus and image processing method for formation of high quality image by high-speed error diffusion processing by execution of more complicated threshold condition processing in a simple manner. When error diffusion processing is performed on multivalued image data having plural density components and the result of processing is outputted, upon execution of error diffusion processing on a first density component among the plural density components, a threshold value used in the error diffusion processing is determined based on a density value of a second density component, then the error diffusion processing is performed on the first density component based on the determined threshold value, and the result of execution of the error diffusion processing is outputted.

Abstract: A printer performs printing after appropriately correcting irregularities, thin-line patchiness, and isolated pixels. A first image-quality corrector unit detects slanting-line irregularities represented by the black and white pixel data generated through binary processing according to a method other than the error-variance method to thereby perform smoothing processing therefor. A second image-quality corrector unit detects defects such as irregularities and patchiness specific to the binary processing according to the error-variance method to thereby perform smoothing processing therefor. A third image-quality corrector unit detects isolated pixels in gray fields that are specific to the binary processing according to the error-variance method to thereby distribute the isolated pixels to peripheral pixels.

Abstract: An apparatus (1100) for halftoning an image is disclosed. The apparatus comprises means for determining an output value of a current pixel on a current scanline using a sum of an input value (1102) for the current pixel and a neighborhood error value (1150) at the current pixel, means (1124) for determining an error at the current pixel as the difference between (i) the sum of the input value (1102) for the current pixel and the neighborhood error value (1150) at the current pixel, and (ii) the output value (1120) of the current pixel; and means (1140) for adding a proportion of the error at the current pixel to neighborhood error values at as yet unprocessed pixels of a subsequent scanline in accordance with a next scanline error impulse response; wherein said next scanline error impulse response approximates a function which spreads with self-convolution in proportion to a degree of self-convolution.

Abstract: Methods, devices and systems for overflow error diffusion in image processing are provided. A method includes calculating error values, em, corresponding to differences between modified intensity values for a number of pixel locations and one or more threshold values, where em represents an error value associated with an mth pixel. The method further includes diffusing a calculated overflow error value associated with each calculated error value, em, to at least one pixel neighbor of the mth pixel location.

Abstract: A method (and system) of embedding data into an image, includes producing an extended image using a halftoning algorithm on a collection of images, and projecting the extended image onto its first coordinates.

Abstract: A printing method and system thereof are described. The locations in a printed image for a plurality of first color (e.g., cyan) dots and the locations in the printed image for a plurality of second color (e.g., magenta) dots are determined. Locations in the printed image for a plurality of third color dots (e.g., yellow) are then determined. The locations for the third color dots are dependent on the locations of the first color dots and the locations of the second color dots. The decision on where to place third color dots is thus made after, and therefore dependent on, the decisions on where to place first color dots and second color dots. Accordingly, color fluctuations in the printed image are minimized, resulting in superior color smoothness and improving the quality of the printed image.

Abstract: A halftoning method and apparatus reduces the occurrence of unaesthetic color print output associated with the different relationships found in the numeric data contained within the color data planes. The calculation, modification and distribution of error values, resulting from the mismatch between color plane values and firing thresholds, are performed in a manner that minimizes unaesthetic conditions. Error values are modified by use of error modification functions, bitmaps and matrixes. Firing decisions are based on a comparison of the modified error.

Abstract: An image processing method of quantizing multi-tone image data by an error diffusion method, includes the steps of a) detecting change of the image data; and b) oscillating cyclically in image space a threshold for the quantization in an oscillation range controlled according to the detection result of the step a).

Abstract: An adaptive halftoning method where the difference between a digital image and a filtered digital image is introduced into the system on a pixel by pixel basis is disclosed.

Abstract: An image processor performs multilevel error diffusion processing and is provided with: a quantizing unit that quantizes pixel data constituting image information based on output values distributed at predetermined tone differences; an error detecting unit that detects a quantization error of the pixel data; a peripheral error calculating unit that integrates the quantization error of the pixel data detected by the error detecting unit with respect to a quantization error of peripheral pixel data; and an error superimposing unit that adds the integration error calculated by the peripheral error calculating unit to the pixel data input next. The image processor is further provided with: a random noise generating unit that generates random noise in accordance with the tone level of the input pixel data; and a noise superimposing unit that superimposes the random noise generated by the random noise generating unit on the pixel data.

Abstract: An image processor unit minimizes image-quality degradation that can be caused by the addition of predetermined information to an image and that enables the predetermined information to be added to the image so that embedded information can be accurately extracted. The image processor unit includes an input unit for inputting the image; a plurality of quantization-threshold setting unit, of which occurrence probability distributions are different from one another, for setting quantization thresholds in terms of probability; a control unit for controlling a regularity for selection of the plurality of quantization-threshold setting unit in units of a predetermined image region according to the predetermined information; and a quantizing unit that uses quantization thresholds set by the quantization-threshold setting unit and thereby quantizes the image according to an error diffusion method.

Abstract: A method and an apparatus are provided in which a color of an input image can be reproduced with high accuracy by a small number of colors, and an image quality except the color reproducibility can be optimized. A color of each pixel of the input image is converted into one color selected from a plurality of reproducible colors, and an error due to the conversion is diffused into pixels surrounding the target pixel. In this conversion of the number of colors, a plurality of rules to be selected for a plurality of reproducible colors is prepared. One of the plural rules is selected to be applied for the whole or each part of the input image.

Abstract: A method (and system) for producing a halftoned image, includes calculating errors corresponding to a plurality of different viewing conditions of a halftone image, and minimizing a function of the errors, such that the halftoned image appears as a different image under different viewing conditions. Alternatively, in another embodiment, the halftoned image appears as the same image under different viewing conditions.

Abstract: Tone dependent plane dependent error diffusion halftoning takes into account multiple color planes, such as cyan and magenta, when determining the placement of a dot in any of the color planes. The combined tones of the correlated color planes is used to determine the threshold levels against which the combined tones and the accumulated errors for the correlated color planes is compared. Further, tone dependent error weightings are determined based on the combined tones of the correlated color planes. The tone dependent error weightings are used to diffuse the final accumulated errors for each color plane. A prerendered mid-tone bitmap may be used to break up any structured patterns that occur in the mid-tones. Using this technique, printed dots of two or more colors are dispersed so as to avoid noticeable clumping of dots of two or more colors to provide a more uniform pattern and to avoid the unintentional overlapping of colors. This technique can be used to augment any existing error diffusion method.

Abstract: A method for reducing or eliminating residual error when “blank” pixels are found in the input image data is provided, such as one that can be used in printers of the type which use error diffusion as part of the halftoning process. When a blank pixel is found, the residual error may be immediately reduced in magnitude in one embodiment. In another embodiment, a “hop count” value is increased (or incremented) when a blank pixel is found, and if sufficient consecutive blank pixels exist in the input data, the hop count achieves a threshold and then either decimates or eliminates the residual error, thus limiting the migration of residual error. If a non-blank pixel is found in the input data before the threshold is achieved, the hop count is reset to zero.

Abstract: A continuous-tone image data is converted to a bi-level image data by halftoning conversion, then the bi-level image data i.e. binary image data is compressed by compressing means including predictive coding and image data compressing. These operations are done in a image coding apparatus. In this apparatus, when the continuous-tone image is converted into bi-level image data in halftoning so that predictions of predictive coding become strong. As a result, halftoning conversion is performed within a scope of binary image-coding-rules. This permits to produce a binary data easy to compress. Compressing a binary data in a low distortion quality and at a high compression rate is achievable through a method of image coding, and by an image coding apparatus of the present invention. Also a recording medium including a program carrying out this method is obtainable.

Abstract: A binary image generating method and apparatus using location information of minority pixels. A modified input pixel value u(m, n) is calculated by adding a value obtained by filtering an error value e(m, n) of a previous binary pixel to a currently input continuous tone pixel value i(m, n). An ideally optimum distance dopt(i(m, n)) between the currently input continuous tone pixel value i(m, n) and a minority pixel is calculated. A minimum distance dm between the input pixel and minority pixels is calculated using location information of the minority pixels at minimum distances from binary pixels adjacent to the input pixel. A threshold value t(m, n) is calculated using the ideally optimum distance dopt(i(m, n)) and the minimum distances dm for the currently input continuous tone pixel value i(m, n). The threshold value t(m, n) is compared with the modified input pixel value u(m, n) to determine a binary pixel value b(m, n) of the input pixel.

Abstract: A method and apparatus for processing an image are provided that can suppress blur edges at an edge portion of a character so that sharpness and quality of the image can be improved. The apparatus comprises an inside and outside edge discrimination portion for discriminating whether a target pixel to be processed belongs to an inside edge or to an outside edge, a threshold value generating portion for selecting a threshold value from plural threshold values for error diffusion process in accordance with an area discriminated by the inside and outside edge discrimination portion to output the selected threshold value and an error diffusion process portion for performing the error diffusion process for multilevel input data concerning the target pixel by utilizing the threshold value generated by the threshold value generating portion so as to produce output data whose gradation steps are reduced.

Abstract: An output halftone image is formed from an input image having a plurality of input image pixels. The output image is formed by processing the input image pixels with a halftoning process that incorporates a hard dot stability constraint. The halftoning process forces a determination to produce a dot for each of N output halftone image pixels following an output halftone image pixel dot that would otherwise be isolated, where N≧1.

Abstract: A method and system for halftoning images that uses error diffusion with partial dots is provided. First, an input picture element (input pixel) that has a picture level (e.g., gray level) is received. Next, a reproducible gray level is generated based on the gray level of an input pixel. Then, a corrected gray level is generated based on the gray level of an input pixel and an error amount (e.g., error propagated or diffused from adjacent areas or pixels). A determination is made whether the corrected gray level is in a predetermined relationship with a threshold. When the corrected gray level is in a predetermined relationship with the threshold, the reproducible gray level (i.e., partial dot size) is provided as output. When the corrected gray level is not in a predetermined relationship with the threshold, a zero value is provided as output.

Abstract: Error addition section 201 generates correction data by adding correction value Emo and correction value E1 to the input data. Binary processing section 202 converts the correction data to binary data to generate output data. Binary error calculation section 203 calculates binary error E based on the correction data and output data. Propagation coefficient judgment section 204 judges propagation coefficients K1 to K4. Propagation error operation section 205 operates on binary error E and propagation coefficients K1 to K4 to calculate correction value E1 and correction value Emi. Error memory 206 temporarily stores correction value Emi, and outputs it to error addition section 201 when the pixel data to be corrected is input.

Abstract: Color processing architecture and algorithms (CPAA) for color laser printers process and handle incoming RGB image data effectively to achieve high performance, high quality image printing with low memory requirements. CPAA supports a new data structure for faster raster operation processing (ROP) for color laser printers. The CPAA architecture advantageously improves the flow of data through the processing pipeline to provide high speed at higher resolutions, e.g., at 600 and 1200 dpi. An advance quantizer using multilevel dithering flexibly reduces bits to support fast ROP and to enable fast conversion to CMYK data with only a simple look-up table (LUT) operation by a color matching module, while an adaptive filter maintains high image quality.

Abstract: A method and apparatus for forming multi-level dither images from an input digital image are disclosed. The difference between a pixel value of the input digital image and a pixel value of a dither image corresponding to the input digital image is first determined. Next, the difference is processed by an error filter to correct the pixel value of the input digital image to generate a corrected image pixel value. The corrected image pixel value is then compared to at least two threshold values, each corresponding to a pixel value of the dither image, to determine a threshold value that is nearest to the corrected image pixel value, thereby obtaining a pixel value of the dither image corresponding to said threshold value.

Abstract: In the error diffusion technique for digital halftoning the output color for a first pixel is selected by comparing an adjusted input color signal to a boundary separating output colors in a pallette for a display device. The error or difference between the selected output color and the input color signal is determined and portions of that difference are added to the input color signals for neighboring pixels diffusing the error throughout the area neighboring the first pixel. Error diffusion can create artifacts in the image as rendered by the display device. Error diffusion artifacts are reduced or eliminated by a higher order error diffusion method where the boundary separating output colors in the device's pallette is adjusted as a function of the error in a previous pixel.

Abstract: An image processing apparatus executes an error diffusion process to multivalue image data consisting of a plurality of density components. A first processor executes the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for the error diffusion process based on a value of the multivalue image data of the density components or a value calculated from the multivalue image data value. A second processor executes the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for the error diffusion process into fixed values. An error diffusion processing controller controls to execute the error diffusion process to at least one color among the density components by the first processor and execute the error diffusion process to other density components by the second processor.

Abstract: A device to translate an input pixel value to an output pixel value for a current pixel includes a diffusion block to produce a diffusion error to add to the input pixel value to produce a diffused pixel value. In addition, the device includes a feedback modulation block to generate a threshold value, the threshold value determined using a value of an earlier output pixel value, the earlier output pixel value occurring at a predetermined number of pixels prior to the current pixel. Furthermore, the device includes a quantizer to compare the diffused pixel value to the threshold value and based on the comparison to select a value for the output pixel value.

Abstract: Circuits for rendering according to the present invention are operable to function in either halftone mode or error diffusion mode. A pixel multiplexor selects between a rasterized unrendered pixel signal from an input rasterized unrendered datastream in halftone mode and an error diffusion adjusted pixel signal generated by error diffusion hardware in error diffusion mode. A memory stores the current error diffusion state signal and retrieves it as the previous error diffusion state signal during the processing of the appropriate pixel in the next scan line in error diffusion mode. A threshold multiplexor selects between an error diffusion threshold signal and a halftone threshold signal. In halftone mode, the memory is operable to retrieve a halftone threshold signal which is supplied to the threshold multiplexor.

Abstract: A method and system which converts an electronic binary image to another electronic binary image by compensating for the differences between printer responses so that a target printer can print the image to emulate how the image would appear if printed by an originally-intended printer or another printer. A print-ready binary image is inputted into a print and scan simulation circuit which electronically simulates the printing and scanning of the image data. The print and scan simulation circuit converts the binary image data to gray scale image data. The gray scale image data is then processed by a tone response correction circuit. The tone response correction circuit alters the gray scale image data based on the difference between the tone reproduction curves of two printers, such as an originally-intended printer and a target printer.

Abstract: An output color is selected for a subject pixel by comparing an input color signal to a boundary separating available output colors. The input color signal is adjusted, at least in part, to reflect a relationship between the output color and the input color signal for another pixel. The boundary is adjusted, at least in part, to reflect a change in the magnitude of a noise source.

Abstract: An image processing apparatus includes an error correcting section for correcting an input image on the basis of a supplied error correction amount and outputting a corrected image, a threshold processing section for processing the corrected image on the basis of a predetermined threshold, further processing the corrected image on the basis of the error correction amount, and outputting an output signal, a correction amount calculating section for calculating in advance a plurality of correction amounts corresponding to possible values of the output signal in parallel with processing of the threshold processing section on the basis of the corrected image output from the error correcting section, and selecting one of the plurality of error correction amounts as the error correction amount in accordance with the value of the output signal actually output from the threshold processing section, and an error correction amount supplying section for supplying the error correction amount calculated and selected by th

Abstract: One method for halftone image watermarking assigns halftone watermark dot values to pseudorandom locations in an image and diffuses the error of the watermark to neighboring pixel locations of these dots. This method may be used in conjunction with a robust watermark spread throughout image before embedding the halftone watermark. The robust watermark carries a key used to decode the halftone watermark. Another method for halftone image watermarking computes a watermark image at the resolution of a halftone image. The method modulates the halftone image with the watermark image.

Abstract: A method for adaptive error diffusion. The method includes the steps of receiving input image data, detecting edges in the input image data, and then adding noise to the input image data depending upon results of said edge detection. The amount of noise is higher for pixels with higher edge content, unless the pixel is on an edge that is already sharp. Once the noise is added the method performs error diffusion on the noise-enhanced image data and it produces output image data. Alternatively, noise can be added to the thresholding portion of the error diffusion process.

Abstract: There is provided an image processing apparatus that can reduce the overlap of dots to thereby enable achievement of favorable visual characteristics, and reduce the amount of pseudo outlines in half tone and reduce the quantity of inks to be shot to thereby suppress an increase in the running cost. When performing the error diffusion on a first density component of the plurality of density components, a threshold to be used for the error diffusion is determined based on a density value of at least one second density component of the plurality of density components. The error diffusion on the first density component is executed based on the determined threshold. A result of the executed error diffusion is outputted.

Abstract: Disclosed are an image processing apparatus and method for the purpose of preventing overlapping of dots between two colors in low-density areas in color pseudo-grayscale processing, thereby obtaining excellent placement of the dots of each color. When a color image is binarized, an error is added to a respective one of color components (I0,I1), after which output decision means (2) decides an output value in accordance with the value of the sum in such a manner that the sum of pixel values after conversion will be rendered constant. Error calculation means (3-0, 3-1) calculate differences between pixel values before and after binarization as errors, and error diffusion means (9-0, 9-1) calculate values to be diffused to a neighboring pixel. Weighting coefficients used at such time are decided in accordance with combinations of values of the color components (I0,I1) of pixel values in the original image. The output value decided by the output decision means (2) is printed out by a printer or the like.

Abstract: In an image processing apparatus which performs an error diffusion process to multivalued image data consisting of plural density components and outputs a result of the error diffusion process, the process result from a first error diffusion unit performing the error diffusion process based on a density value of a first density component included in the plural density components or the process result from a second error diffusion unit performing the error diffusion process based on the density value of the first density component and a density value of at least one density component included in other density components is selected according to a predetermined condition. Thus, even in an image process is performed to a larger number of gradations, a high-speed process can be achieved with simple structure, and the error diffusion process can be effectively performed to a shift of dot apply positions.

Abstract: The present invention accurately reproduces an image pattern by referring to neighboring pixels upon determining the threshold value of a target pixel so that a delay in dot generation can be prevented while emphasizing an image transition portion so that both graininess and sharpness are improved in the image. To this end, a neighboring pixel density difference detection part obtains an absolute value of the density difference between a target pixel and its neighboring pixels and selects the density of a neighboring pixel with a large absolute value as a reference pixel density. Further, a threshold value quantity determination part determines a threshold value corresponding to the density selected by the neighboring pixel density difference detection part. Then, a quantization part outputs an output value based on a comparison between the threshold value and a corrected value obtained by adding a pre-calculated error value of neighboring pixels to an input value.

Abstract: A threshold modulation method, includes the steps of: a) determining whether an input pixel value is greater than a threshold of a current input pixel from the original digital image; b) determining whether an output image value is a predetermined high level or low level based on the threshold; c) if the input pixel value is greater than the threshold and the output image value is the predetermined high level, modulating the threshold of the adjacent pixel; d) if the input pixel value is greater than the threshold and the output image value is the predetermined low level, modulating the threshold of the adjacent pixel; e) if the input pixel value is not greater than the threshold and the output image value is the predetermined low level, modulating the threshold of the adjacent pixel; and f) if the input pixel value is not greater than the threshold and the output image value is the predetermined high level, modulating the threshold of the adjacent pixel.

Abstract: A method of changing a halftone dot area is provided. The method includes: performing an expansion process on rasterized binary halftone image data to generate multi-level halftone image data; processing the expanded halftone image data using an averaging mask to convert the expanded halftone image data into multi-level halftone image data having intermediate gradation levels; performing a gradation conversion on the multi-level halftone image data having the intermediate gradation levels based on a predetermined tone curve to perform a spreading/shrinking process for changing a density in an edge portion of a halftone dot; and performing an error diffusion process based on the corrected gradation to represent gradation in the form of small dots having densities corresponding to original gradation levels, thereby generating halftone data for proof in which the halftone dot area is changed in accordance with the output characteristic of an output device.

Abstract: There is described a compound apparatus, having a plurality of outputting functions including at least a copy function. The compound apparatus includes: an image-reading device to read an original image residing on a document so as to convert the original image into image data; a binary-coded image data generating section to generate binary-coded image data by applying a binary-coding processing to the image data; an image-data storing section to store the image data or the binary-coded image data; a designating section to designate an outputting function among the plurality of outputting functions; a resolution setting section to set an output-image resolution, based on an output resolution of the outputting function; and a resolution converting section to convert a resolution of either the image data or the binary-coded image data, stored in the image-data storing section, to the output-image resolution set by the resolution setting section.

Abstract: An error diffusion halftoning system and a method of managing halftoning errors utilize a quantization technique to reduce the required size of a primary error buffer that is needed to diffuse the halftoning errors. By implementing the quantization technique, the primary error buffer can be reduced from an 8-bits-per-bin error buffer to a 2-bits-per-bin error buffer for 256 grayscale. The reduction in bin size decreases the cost of the primary error buffer and, consequently, the cost of an error diffusion halftoning (EDH) device of the system that generates halftone values from grayscale values of a digital image. The quantization technique is executed on cumulated half-toning errors, derived from apportioned halftoning errors associated with previously processed pixels. In addition, the system and method utilize an error diffusion procedure to diffuse quantization errors that are produced from the execution of the quantization technique.

Abstract: Tone dependent plane dependent error diffusion halftoning takes into account multiple color planes, such as cyan and magenta, when determining the placement of a dot in any of the color planes. The combined tones of the correlated color planes is used to determine the threshold levels against which the combined tones and the accumulated errors for the correlated color planes is compared. Further, tone dependent error weightings are determined based on the combined tones of the correlated color planes. The tone dependent error weightings are used to diffuse the final accumulated errors for each color plane. A prerendered mid-tone bitmap may be used to break up any structured patterns that occur in the mid-tones. Using this technique, printed dots of two or more colors are dispersed so as to avoid noticeable clumping of dots of two or more colors to provide a more uniform pattern and to avoid the unintentional overlapping of colors. This technique can be used to augment any existing error diffusion method.

Abstract: Tone dependent plane dependent error diffusion halftoning takes into account multiple color planes, such as cyan and magenta, when determining the placement of a dot in any of the color planes. The combined tones of the correlated color planes is used to determine the threshold levels against which the combined tones and the accumulated errors for the correlated color planes is compared. Further, tone dependent error weightings are determined based on the combined tones of the correlated color planes. The tone dependent error weightings are used to diffuse the final accumulated errors for each color plane. A prerendered mid-tone bitmap may be used to break up any structured patterns that occur in the mid-tones. Using this technique, printed dots of two or more colors are dispersed so as to avoid noticeable clumping of dots of two or more colors to provide a more uniform pattern and to avoid the unintentional overlapping of colors. This technique can be used to augment any existing error diffusion method.