摘要:
Disclosed herein is an image processing method for producing enhanced halftone edges, particularly suited to those edges which only lie upon the background as apposed to those edges which abut other halftone screens. It utilizes a step of defining border pixels and a step of halftoning those border pixels in a different manner than the halftoning applied to the interior region of the tint or image segment. The preferred halftone for the border pixels will be related to the interior halftone by some number of common spatial frequency harmonics. Examples of common-harmonic screening for an edge include, but are not limited to: (a) same screen with different tone reproduction characteristics (boosted edge values); (b) same screen angles and frequencies with a different spot function, possibly phase shifted; (c) a dot screen whose frequency vectors can be generated by the frequency vectors of the interior screen; (d) a line screen whose frequency vectors can be generated by the frequency vectors of the interior screen. This generation process is directed to ensuring that the two screens will be “harmonically matched” where at least one of the fundamental frequency vectors and harmonics of the first screen will equal at least one of the fundamental frequency vectors and harmonics of the second screen.
摘要:
An object optimized printing system and method comprises a page description language decomposing system, a command instruction and data generating system and an image output terminal controller. The PDL decomposition system inputs a print file defining a plurality of pages in the page description language and locates the plurality of objects forming each page and their object types. Based on the determine object types and any explicit rendering commands in the PDL file, the PDL decomposition system automatically generates rendering tags for each of the objects. The rendering tags are used to control the command instruction and data generating system, the IOT controller and/or the image output terminal to optimize the printing by the IOT on an object-by-object basis. Based on the objects and the generated rendering tags, the command instruction and data generating system generates the differing types of data and the command instructions on a scanline-by-scanline basis. The generated command instructions and data are output to the IOT controller scanline-by-scanline. The data output to the IOT controller includes metabit data which is generated from the rendering tags. The metabit data output to the IOT controller is used to control various subsystems of the IOT controller and the IOT to optimize the printing characteristics of the IOT for each differing object on each scanline.
摘要:
This is a halftone circuit which, in addition to the usual counting and addressing mechanisms, has control over the phase, angle and direction of the addressing circuitry of the array in memory so that regular dots, mirror images of dots and out-of-phase dots can be created from a single array, thus saving memory hardware. The mirror images can be made by counting rows in either direction, the angle can be varied by varying the number of pixels shifted between scans, and the phase can be varied by setting the starting point to any row and column. In this way, a single array can be used to create a number of dots.
摘要:
A method and apparatus are provided for improving the quality of a printed image by first automatically determining the gamma (&ggr;) of an image, and then adjusting the &ggr; of the printer, if necessary, to correspond to that of the image. Thus, if an image has a &ggr; of 2, the &ggr; of the printer will be adjusted from approximately 1 (its normal &ggr;), to approximately 2 (i.e., corresponding to that of the image). To detect the &ggr; difference problem, the invention detects a shift in saturated colors towards higher digital counts. Then, through mapping of the color space from three dimensions to two dimensions and cross-plotting values of saturation and luminance, a cumulative histogram plot of luminance is developed. The histogram displays the 256 luminance bands, arranged in one of eight bands, and normalized from zero to one. A threshold value is established for the cumulative histogram plot and the value of the cumulative histogram is compared to the threshold. If the threshold is exceeded in most of the bands, the &ggr; for the image matches that of the printer. However, if the threshold is not exceeded, a false &ggr; image may be indicated, for example. In this case, the &ggr; of the printer may be automatically adjusted (e.g., increased from approximately 1 to approximately 2). Thus, the printed image will then be of the same quality as the original image.
摘要:
Conventional design tools were not developed for designing square zero-shift supercells. Conventionally, solutions that enable square zero-shift supercells were found by trial and error or by exhaustive analysis. According to a first design criterion of this invention, a non-square supercell in a first frame of reference has a diagonal that is equal in length to the diagonal of a square supercell in a second frame of reference rotated at a desired screen angle to the first frame of reference. The screen angle is a function of the lengths of the sides of the non-square supercell in the first frame of reference. According to a second design criterion, if the area of the corresponding square supercell in the second frame of reference is an integer, a square zero-shift supercell can be designed based on the lengths of the sides of the non-square supercell in the first frame of reference.
摘要:
A method for selecting CMY coordinates for printing a desired source color represented in an source color-space includes the step of obtaining coordinates for the printer gamut in the source color-space and then dividing the printer gamut into a plurality of tetrahedra, one of which contains the desired source color. This particular tetrahedron, referred to as the source-bearing tetrahedron, is identified and transformed into a target-bearing tetrahedron in the CMY color space. The target-bearing tetrahedron contains the CMY coordinates of the desired color. The specific color within the target-bearing tetrahedron is identified by obtaining barycentric coordinates for the source color relative to the source-bearing tetrahedron and identifying that color in the target-bearing tetrahedron that has the same barycenric coordinates. The CMY coordinates for that color can then be provided to a printer to print the desired source color.
摘要:
A set of halftone screens and a write white xerographic system for generating halftone images with a minumum of artifacts. The screens used in a four color printer have at least 64 pixels per pattern and are distributed to creat fourcentered dots that are at either -14, 0,+14 or +45 degrees. The xerographic process involves charging the photoreceptor, partially discharging the photoreceptor with a scanning beam to create an image, and then using toner which adheres to the charged portions of the photoreceptor to create the hard copy.
摘要:
A method for color cast removal in a scanned image in L*a*b* space includes generating a first color cast correction curve for mapping L* to a first color correction, Δa*, (or Δb*) wherein the first correction curve provides a desired a* shift in midtone regions and is modulated as a function of L* such that black and white points are unaffected; for each pixel n in the scanned image, passing L*n through the first color cast correction curve for obtaining a value of Δa*n; and adding the value of Δa*n to the scanned image's original a*n component. To ensure that the color corrected a* remains within gamut, a second correction curve for applying a clipping factor to the mapped Δa* may be generated with the a*n passing through the second correction curve for obtaining a clipping factor Cn; and modifying the a*n value by Cn(Δa*n).
摘要翻译:一种用于在L * a * b *空间中的扫描图像中去色调的方法包括:生成用于将L *映射到第一颜色校正的Deltaa *(或Deltab *)的第一色偏校正曲线,其中第一校正曲线 中间色调区域中所需的*移位,并且被调制为L *的函数,使得黑色和白色点不受影响; 对于扫描图像中的每个像素n,通过第一颜色转换校正曲线的L * SUB>以获得Deltaa * N n的值; 并将Deltaa * N SUB>的值添加到扫描图像的原始a * SUB>分量。 为了确保校正的颜色a *保持在色域内,可以通过经过第二校正曲线的a * N n生成用于将削波因子应用于映射的Deltaa *的第二校正曲线,以获得 剪切因子C SUB> 并且通过C n n n(ΔΔ* N n)修改a * N SUB>值。
摘要:
Historically, the creation of digital line screens was considered to be a subset of the creation of the digital cluster dot screens. The geometric constraints necessary for digital cluster dot screens were imported into the creation of digital line screens. Accordingly, the number of available angles or digital line screens was also significantly limited. In various exemplary embodiments of the systems and methods according to this invention, a digital line screen cell is defined such that the vectors defining the digital line screen cell are not necessarily isometric and are not necessarily at right angles to each other. By using a high-addressability grid that has different resolutions along x and y axis of the grid, the systems and methods according to this invention allow the components of the vectors along the high-addressability direction to be noninteger multiples of the components of the vectors along the other direction of the grid.
摘要:
The system and method reduces aliasing which is formed by the patterns that are introduced by the halftone screens used in the printer. The system and method provides halftone-specific anti-alias filters for obtaining optimal effective resolution in printed images. A method of reducing aliasing in a digital image includes providing a digital image; selecting a halftone screen for halftoning the digital image, wherein the halftone screen has a directional component associated with it; filtering the digital image with an antialiasing filter, the antialiasing filter having been designed to have a directional frequency response that is optimized for the directional component of the selected halftone screen; and halftoning the filtered digital image.