Abstract: A halftone screen may be used to transform a continuous tone image into a halftone image. Determining the halftone screen may include determining a first halftone tile for a first gray level, selecting pixel locations and increasing the intensity of pixels at the locations to activate the pixels to form a second halftone tile for a subsequent gray level. A filtered image may be generated from the second halftone tile, and pixels from the filtered image may be used to generate the halftone screen.

Abstract: An image forming apparatus includes a receiving unit, a dividing unit, and an output controller. The receiving unit receives an output instruction for a report. The dividing unit divides, when the output instruction for the report is received, report items to be output into a main-report item to be output as characters on a recording sheet and a sub-report item to be output as a digital watermark on the recording sheet in such a manner that the report items to be output are formed within a predetermined number of recording sheets or a predetermined number of pages. The output controller causes an output mechanism to output the main-report item as characters on the recording sheet and output the sub-report item as a digital watermark on the recording sheet, based on a division result by the dividing unit.

Abstract: An image forming device includes a density correction unit that corrects density based on a density detection value of the density correction pattern; a first density correction pattern generating unit that generates a first density correction pattern having low resolution; and a second density correction pattern generating unit that generates a second density correction pattern having high resolution. When a first density detection value of the first density correction pattern is greater than a predetermined threshold value, the density correction unit corrects the density by determining a density correction reflection rate, based on the first density detection value. When the first density detection value is less than or equal to the predetermined threshold value, the density correction unit corrects the density by determining the density correction reflection rate, based on a second density detection value of the second density correction pattern.

Abstract: A control device performs: acquiring an optical measured scan value; setting a measured offset using the measured scan value by reference to predetermined correlations; and determining a control value using the measured offset amount. The control value is used for controlling an amount of colorant to be ejected during printing. In the predetermined correlations, a first pair of scan values is associated with a first pair of offsets. A second pair of scan values is associated with a second pair of offsets. The first and second pair has a first and second scan difference between the scan values, respectively. The first and second pair of offsets has a first and second offset difference between the offsets, respectively. The first scan difference is different from the second scan difference. The first offset difference is same as the second offset difference.

Abstract: A method enables primary color values for pixel to be processed before the pixel is rendered. The method includes allocating non-black primary colors as being under black, secondary colors, or tertiary colors.

Abstract: The present invention provides an image processing apparatus that includes a processor. The processor is configured to calculate a corrected tone value of a target pixel using a tone value of the target pixel and an error value of a previously processed pixel; determine a dot value of the target pixel by comparing the corrected tone value with a threshold value; calculate an error value of the target pixel using the corrected tone value and a first density value when the dot value indicates to form a dot and the dot to be formed is a first dot formed in isolation; and calculate an error value of the target pixel using the corrected tone value and a second density value when the dot value indicates to form a dot and the dot to be formed is a second dot formed at a particular location in consecutive dots.

Abstract: A method for controlling the metering of ink in a printing press uses a control unit for comparing measured color values established on a print control strip to target color values and for controlling the metering of ink in the inking units of a printing press. The method is distinguished by the fact that the halftone of the measurement fields used for establishing the measured color values in the print control strip is independent of the halftone of the printed image. A printing substrate, a printing plate and a printing press having a device for creating halftone image data are also provided.

Abstract: A decoding method decodes last position information indicating horizontal and vertical positions of a last non-zero coefficient in a predetermined order within a current block to be decoded, the current block including plural coefficients. The decoding includes obtaining a bitstream including first, second, third and fourth partial signals, in this order, performing first arithmetic decoding on the first and the third partial signals respectively to obtain decoded first and decoded third partial signals, performing second arithmetic decoding on the second and the fourth partial signals respectively to obtain decoded second and decoded fourth partial signals, the second arithmetic decoding being different from the first arithmetic decoding, deriving a horizontal component of the last position information from the decoded first and decoded third partial signals, and deriving a vertical component of the last position information from the decoded second and decoded fourth partial signals.

Abstract: A method is disclosed. The method includes generating a Continuous Tone Image (CTI) with all pixel values same as a first gray level, generating an initial Half Tone Image (HTI) with all pixel values equal to minimum absorptance level and computing a change in pixel error for a first pixel. The change in pixel error is computed by identifying a first pixel indicated in a valid pixel map, toggling the first pixel with all the possible output states and swapping the first pixel with all neighbor pixels only if the stacking constraint is satisfied, updating the HTI with the maximum error decrease operation and continue to next pixel location till the end criteria is met.

Abstract: A color conversion method is utilized for converting a plurality of source information in a source color space to a plurality of destination information in a destination color space. The color conversion method includes obtaining a first color value and a plurality of second color values of a pixel; performing a computation on at least one converting parameter, the plurality of second color values, a plurality of maximum values and minimum values corresponding to the plurality of destination information to obtain a source maximum value and a source minimum value; generating an adjustment value according to the first color value, the source maximum value, and the source minimum value; and performing a computation for obtaining a plurality of destination color values of the pixel according to the at least one converting parameter, the adjustment value, and the plurality of second color values.

Abstract: Screen processing is performed on input image data. A boundary pixel adjacent to a white pixel in the input image data is detected. Output image data based on either the input image data or the screen-processed image data is selectively output for each pixel in accordance with the detection result of the boundary pixel.

Abstract: An image processing apparatus includes processors which output first and second image data from input image data. The second image data is applied halftone processing of a higher resolution than halftone processing applied to the first image data. The image processing includes a unit configured to decide a mixing ratio of a pixel using a value based on a sum of an error of the pixel and a change amount of a pixel value at that pixel; and a mixing unit configured to mix pixel values of the first image data and the second image data according to the mixing ratios. When the value based on the sum is increased, the mixing ratio of the second image data decided by the decision unit remains the same or is increased.

Abstract: An image processing apparatus that converts input image data into printable image data is provided. The apparatus performs screen processing on the input image data, and determines whether moiré occurs in screen image data generated by the screen processing unit for a target pixel in the input image data. Depending on the determination result made by the determination unit, the apparatus outputs one of a screen pixel value in the screen image data for the target pixel and a value obtained by converting an input pixel value into a printable pixel value based on intermediate data, as a value of the target pixel in the printable image data, the intermediate data being generated by replacing a screen pixel in the screen image data that is determined to have moiré by the determination unit with the input pixel value in the input image data.

Abstract: Provided are black trapping methods, apparatus and systems for binary images. According to one exemplary method, black trapping color image data is performed by incorporating a set of trapping condition logical operations. Specifically, edge checking is based on estimated contone color values and density checking based on a binary bitmap.

Abstract: In the present invention, a printing control device comprises: a generation unit that generates a clear toner plane data based on a type of a surface effect which is applied to a recording medium and gloss control plane data for specifying an area in the recording medium to which the surface effect is applied; a first gradation correction unit that performs first gradation correction that varies per combination of a color of colored plane data and the surface effect, with respect to each of a plurality of items of colored plane data that configures the colored plane data; and an output unit that outputs the image data generated based on the clear toner plane data generated by the generation unit and the colored plane data to which the first gradation correction is applied.

Abstract: A control device according to the present invention is a control device that controls a print device that forms an image on a recording medium based on image data in which density values of multiple colors are defined every pixel, including: a stored color setting unit that sets a stored color indicating a color of which a toner amount is not restricted in each object indicating an area in which a predetermined type of image in the image data is drawn, in response to designation from a user; and a determination unit that determines density values of each of colors, in the each object, other than the stored color, such that a total sum of the density values of the colors is within a value subtracting a density value of the stored color from a reference value.

Abstract: A dither matrix creating device acquires a basic dither matrix and modifies the basic dither matrix to provide a modified dither matrix including a plurality of sets of threshold value. Each threshold value set includes N threshold values (N?2. An image processing device can perform both dither method and error diffusion method for converting an input image into an output image. Each pixel of the output image has an (N+1)-level output value. The modifying unit modifies the basic dither matrix by adjusting at least one of N threshold values such that the image processing device can produce a first output image by using the modified dither matrix according to the dither method. The first output image is more similar to an output image produced based on the input image according to the error diffusion method than an output image to be produced by using the basic dither matrix.

Abstract: The printing apparatus includes a comparator, a threshold setting section, and an error diffusion section. The comparator compares a first threshold which is aligned with a dither mask and the image data. The threshold setting section sets a second threshold which is used in the error diffusion method to one of a low threshold and a high threshold according to results of the comparing, and sets the low threshold to a value which is smaller than a gradation range of the image data in at least a low gradation area when it is determined that the image data exceeds the first threshold. The error diffusion section generates the dot data and to calculate distribution to pixels in the vicinity of gradation errors by comparing correction data where error distribution in the image data is complete using the error diffusion method and the low threshold or the high threshold.

Abstract: A watermark and a manufacturing method therefor are provided. The watermark has a first region comprising amplitude modulation (AM) halftone dots and a second region comprising frequency modulation (FM) halftone dots, and each of the amplitude modulation halftone dots has ink portions and blank portions, each of which is located between the two ink portions in the same amplitude modulation halftone dot. The ink area percentage of the amplitude modulation halftone dots are dispersed by filling the blank portions into each of the amplitude modulation halftone dots, so that the density calibration of the amplitude modulation halftone dots and frequency modulation halftone dots can be omitted.

Abstract: A vector image drawing device has the following configuration. A contour generation unit (104), based on vector data, generates contour data that represents the starting pixels on a scan line in a drawing area where fill-in starts, and the ending pixels where fill-in ends. An outline buffer (106) stores the number of starting or ending pixels in the contour data for fill-in for each drawn pixel. An error judgment unit (2), when storing the contour data in the outline buffer (106), determines in which pixel there is overflow in the outline buffer of contour data. A pixel position transfer unit (3) adds the numerical value of the overflow portion of a pixel that the error judgment unit (2) determined to have overflow to the numerical value of contour data that corresponds to a pixel.

Abstract: Provided is a control apparatus for controlling an image forming apparatus including an inline sensor. The control apparatus includes: a data analyzing section configured to extract color information contained in an image of a target page positioned a predetermined number of pages after a certain page, where the predetermined number of pages are pages to be printed during at least a period from print processing for the certain page to measurement of color information on the printed image of the certain page; a color patch creating section configured to create a color patch corresponding to the color information contained in the image of the target page and arrange the color patch in the certain page; and a control section configured to send image data of the certain page to the image forming apparatus so as to make the image forming apparatus perform print processing and measuring color information.

Abstract: Multi-value image data is sampled for each predetermined pixel range to generate tone information of the pixel range. The generated tone information is stored in a storage unit. Attribute information representing the attribute of a pixel is generated from the multi-value image data, and the generated attribute information is stored in the storage unit. Halftone processing is performed on the multi-value image data based on the tone information and attribute information stored in the storage unit.

Abstract: A multicolor image can include multiple overlaid items including a black region covering a color region. Raster image processing adds the color data to color pixels of the raster data print page uniformly across the area of the raster data print page that corresponds to the color region of the multicolor image, and adds the black data to over-print pixels (where the black region covers the color region in the multicolor image). Such over-print pixels include both the color data and the black data. The color data (but not the black data) is removed from the over-print pixels that are positioned a preset pixel distance from non-black color pixels. The raster data page is output from the processor device to a printing engine, and the printing device prints the raster data page on print media to produce a physically printed reproduction of the multicolor image.

Abstract: Methods and devices identify gloss levels and appearance colors for different printers based on the common printing capabilities of the different printers. Such gloss levels and appearance colors are formed from different combinations of one or more colorant marking materials combined or stacked on a print substrate surface. Further, such methods and devices identify common color metameric pairs based on the gloss levels and the appearance colors. Each of the common color metameric pairs has the same appearance color, but has a different gloss level. Patterns of different gloss levels in an area of uniform appearance color form a differential gloss security feature on a printed document. The methods herein can store a file with the common color metameric pairs in a non-transitory storage medium that is operatively connected to at least one of the different printers.

Abstract: When an input image is shifted by 640 pixels from a test pattern with reference to the position of a nozzle, the remainder is obtained by dividing 640 pixels by pixels of the dither matrix in an x direction. For example, when the size of the dither matrix in the x direction is 256 pixels, the dither matrix is shifted by 128 pixels in a direction reverse to the x direction. In this manner, the phase of the dither matrix at the time of the quantization during test pattern printing matches the phase of the dither matrix at the time of the quantization during input image printing. Consequently, unevenness of the dither matrix at a position N becomes the same in both of the test pattern and the input image. The HS correction to density unevenness caused by the unevenness of the dither matrix becomes suitable for the input image.

Abstract: A method of forming a halftone screen comprising representing each of a first, second, third and fourth tone range of increasing darkness by forming a plurality of dots arranged in a grid; the dots representing the second tone range larger than the dots representing the first tone range; the dots representing the third tone range having a body section and at least one extension extending toward a or respective nearest neighbour(s), the extension(s) narrower in width than the body section, the dots representing the third tone range substantially the same size as the dots representing the second tone range; and the dots representing the fourth tone range having a body section and at least one extension extending toward a or respective nearest neighbour(s), the extension(s) greater in width than the extension(s) associated with the dots representing the third tone range. A halftone screen and a printing system are also disclosed.

Abstract: A method and system for generating a document having a void pantograph highlight pattern is presented. The method includes computing a score for a void pantograph highlight pattern layer in relation to a document formatted content layer, incrementing a relative position of the void pantograph highlight pattern layer and the document formatted content layer, repeating the computing and the incrementing steps to obtain a plurality of scores at a plurality of relative positions, evaluating the plurality of scores to determine an optimal alignment, and printing the document using variable-data printing techniques, wherein the printed document has a multi-layer architecture including the document formatted content layer and the void pantograph highlight pattern layer. The system includes a control processor, a score computation unit and an evaluation unit.

Abstract: A system can comprise a memory to store machine readable instructions and a processing unit to access the memory and execute the machine readable instructions. The machine readable instructions can comprise a feature set extractor to extract a feature set from each of a plurality of digital images of print samples. The feature set can be a filtered feature set that includes a feature set characterizing a printer that printed a given print sample of the print samples. The machine readable instructions can also comprise a cluster component to determine clusters of the print samples based on the feature set of each of the plurality of scanned images of the print samples. The machine readable instructions can further comprise a printer identifier to identify the printer of the print samples based on the clusters of the print samples.

Abstract: An image processor includes a color conversion unit that generates color converted image data by converting color data and an error diffusion process performing unit that generates print data by performing an error diffusion process on the color converted image data. The error diffusion process performs a first error diffusion process on remaining data and performing a second error diffusion process on edge data such that an amount of ink used in the edge region by performing the second error diffusion process on the edge data is less than an amount of ink used in the edge region by performing first error diffusion process on the edge data.

Abstract: Embodiments provide a method comprising receiving a continuous tone (contone) image, wherein each pixel of a plurality of pixels of the contone image comprises pixel data associated with a plurality of color planes; forming a pixel group that includes a target pixel and one or more pixels that are neighboring to the target pixel; for each pixel in the pixel group and for each of one or more color planes of the plurality of color planes, comparing pixel data of the corresponding pixel for the corresponding color plane with one or more threshold levels to generate threshold pixel data; generating one or more color plane pixel windows for the pixel group corresponding to the one or more color planes; and generating a pixel window for the pixel group.

Abstract: A halftone screen may be used to transform a continuous tone image into a halftone image. Determining the halftone screen may include determining a first halftone tile for a first gray level, selecting pixel locations and increasing the intensity of pixels at the locations to activate the pixels to form a second halftone tile for a subsequent gray level. A filtered image may be generated from the second halftone tile, and pixels from the filtered image may be used to generate the halftone screen.

Abstract: A method of producing a bit-map including rendering a bit-map of a first image using a first stochastic half-tone screen set, rendering a bit-map of a second image using a second stochastic half-tone screen set, wherein the first half-tone screen set and the second half-tone screen set have respectively associated stochastic half-tone screens, and wherein each half-tone screen of the second half-tone screen set is less than 100 percent correlated with, and not an inverse of, the associated half-tone screen of the first half-tone screen set; and merging the bit-map of the first image with the bit-map of the second image.

Abstract: A printing apparatus for combining a document image with a copy-forgery-inhibited pattern image to perform printing includes a unit configured to determine a video count value from the document image, a unit configured to determine a video count value from the copy-forgery-inhibited pattern image, and a unit configured to multiply the video count value determined from the document image by a rate of dots other than dots constituting the copy-forgery-inhibited pattern image in the document image to obtain a product, and to add, to the product, the video count value determined from the copy-forgery-inhibited pattern image to determine a video count value for the printing.

Abstract: An image may be quantized into a pattern of dots, e.g., for devices capable of printing dots of variable size and variable color intensity. One may use a pre-determined mapping of the continuous-tone intensity value into a discrete vector of intensity values, and each intensity value may then be processed by a set of binary quantizers. The resulting binary vector may then be mapped into a combination of available dot sizes and color intensities. Through a scalar multiplier, the pre-determined mapping of continuous-tone intensity values may be used at multiple print resolutions.

Abstract: The present application discloses a method and an apparatus for generating multi-bit depth halftone amplitude-modulation dots. The method may comprise: scanning an input image to obtain a value of a current pixel Pxy, where x represents a lateral position index of the current pixel, and y represents a vertical position index of the current pixel; obtaining gj from a preset multi-bit depth threshold matrix G by starting with i=0, and determining if Pxy<gj, then providing a screening output gray level gradation value of the printer to Out=L?1?i; and otherwise, increasing i and repeating the determining and providing steps. L represents the number of a frequency-modulation screen gradation, L=2e, e represents a bit depth value of the printer, i is an integer and i?[0,L?1], h is an index number of an element g arranged sequentially in G and h is provided to h=(y % n)×m+(x % m)+i×m×n, and gj is the element value of ith line and jth row in G.

Abstract: A host computer generates pseudo-pixels by grouping pixels together. RGB representative values are assigned to the pseudo-pixels, which are then transferred to a printer. Meanwhile, for pixels that configured pseudo-pixels having an edge strength selected so that the transfer data amount is less than or equal to a predetermined value, the host computer carries out a halftone process and then transfers the dot data generated as a result to the printer. The printer then prints based on the transferred dot data and the representative values.

Abstract: The present invention provides stereoscopic prints with enhanced resolution and reduced image coarseness. A stereoscopic print comprises a lenticular lens sheet and a dot image print that is glued to the back surface of the lenticular lens sheet. The order of printing dots for the pixels of tone-representing smallest units with the use of a color plate is set at random. The dot printing order is the same among a given number of image strips forming an image strip group that are continuously arranged in a direction perpendicular to a longitudinal direction of half-cylindrical lenses so that dot printing is performed continuously on an area in which pixels to be printed are continuous.

Abstract: A contone source image is processed to create halftone outputs by identifying intensity thresholds based on the coordinates of the pixels of the source image. The halftone output corresponding to a particular pixel of the contone image in a particular color plane is determined by comparing the intensity of the pixel and any previously accumulated output error to the intensity threshold corresponding to the pixel.

Abstract: Provided is an image determination device including a sheet detecting unit that detects a sheet on which a code image is printed, a first acquiring unit that acquires information on the code image and an absorption wavelength of the code image, a second acquiring unit that acquires a reading unit necessary for decoding a code portion of the code image, a third acquiring unit that acquires a document image of an electronic document, a dividing unit that divides the document image into plural blocks corresponding to the reading unit, a detecting unit that detects a block in which an image portion of the document image that uses a color having an absorption band at the absorption wavelength of the code image overlaps with the code portion of the code image as an undecodable block, and an output unit that outputs a warning indicating the generation of an undecodable area.

Abstract: A page-wide-array printer has a print unit including an array of print-heads, wherein a printing direction is defined by a relative movement between the print unit and a print medium during a printing process. The page-wide-array printer receives a continuous tone image and divides the continuous tone image into a series of slices along a printing direction. Halftone image data is generated from each of the slices using error diffusion halftoning. The error diffusion halftoning comprises processing, with regard to error diffusion, each slice pixel-by-pixel following a processing pattern mainly oriented along a main processing direction which is parallel to the printing direction. The page-wide-array printer prints the halftone image data along the printing direction.

Abstract: Based on an m×n halftone matrix and an m×n pixel block of an image, an m×n halftone version of the m×n pixel block may be determined. An n-way interleave may be performed on rows of the m×n halftone version to create an mn×1 halftone segment. The mn×1 halftone segment may be compared to one or more halftone segments in a buffer. Based on the comparison, a literal code word and a representation of the mn×1 halftone segment may be output, and the representation of the mn×1 halftone segment may be written to the buffer. Alternatively, a repeat code word and a repeat value may be output, and at least one representation of the mn×1 halftone segment may be written to the buffer.

Abstract: A method for creating an image to be printed is provided. A first halftone pattern and a second halftone pattern for respective first and second periodic clustered dot halftone regions of the image are selected. The regions have respective frequencies and one of the frequencies is higher than the other frequency. A transition region is determined. The transition region includes a boundary between the two regions and includes additional portions of the two regions beyond the boundary. The two halftone patterns are blended with each other in the transition region based on a blending ratio of the two halftones where the blending ratio changes as a function of distance between the edges of the transition region.

Abstract: An image recording apparatus generates black, cyan, magenta, and yellow halftone image data from a multi-tone color image. When the cyan halftone image data is generated, the size of a cyan dot to be formed at a target pixel position is provisionally determined and added to the size of a black dot to obtain a total dot size. When the total dot size is less than or equal to a first threshold dot size, the cyan dot size is determined to be the provisionally determined size, and when the total dot size is greater than the first threshold dot size, the cyan dot size is determined to be the largest dot size within the range of a difference between the first threshold dot size and the black dot size. It is possible to prevent excessive overlapping of black and cyan dots.

Abstract: A threshold matrix generation part determines a turn-on order in a matrix area where a threshold matrix is generated and determines a threshold value of each matrix element. In determining the turn-on order, a temporary evaluation value element is obtained based on a distance between each undetermined matrix element whose position in the turn-on order has not been determined and each determined matrix element. If these matrix elements are located in the same position with respect to a row or column direction, the temporary evaluation value element is corrected such that the undetermined matrix element is less evaluated based on the evaluation value. Then, the position of an undetermined matrix element that is most highly evaluated in the turn-on order is determined. Accordingly, a threshold matrix that suppresses the occurrence of a grid-like dot pattern can be provided.

Abstract: A printing apparatus, which performs printing using a cyan ink, a magenta ink, a yellow ink, and two kinds of black inks, includes an image data acquisition section configured to acquire image data representing an image targeted for printing; a black line specification section configured to specify a black line included in the image on the basis of the image data; a printing control section configured to perform control so as to, along with performing printing of the black line by using the two kinds of black inks, perform printing with respect to pixels forming at least one portion of the black line so as to overlap the two kinds of black colors, and perform printing of a portion other than the black line by using at least one of the cyan ink, the magenta ink, the yellow ink, and the two kinds of black inks.

Abstract: A host computer groups a plurality of pixels to generate pseudo pixels, assigns representative values in an RGB format to the pseudo pixels, and transfers the representative values to a printer. Further, the host computer performs halftone processing and transfers generated dot data to the printer for pixels constituting the pseudo pixel which includes edges therein or of which boundary is the edge. The printer performs printing by using the transferred dot data and the representative values.

Abstract: An image data processing apparatus processes previously halftoned data that has been halftoned so that a proportion of dot formation corresponding to gradation values of an image reaches a first dot generation rate, as image data representative of the image.

Abstract: An image forming apparatus includes an image density detector, an image forming device, a rotator, an image density controller, and a timing correction data obtainer. The image density detector detects a toner density of an image formed on an image bearing member. An image forming device forms the image using a density adjustable element that adjusts the density of the image. The rotator forms an image pattern while the density adjustable element is changed, and a density thereof is detected by the image density detector. The image density controller controls the image forming device using a density correction data for the density adjustable element corresponding to a rotational period of the rotator. The timing correction data obtainer obtains timing correction data for correction of driving timing of the image forming device based on a change in the density of the image pattern detected by the image density detector.

Abstract: The invention relates to identification documents, and in particular to pre-printing processing covert images, such as UV or IR images, provided on such identification documents. In one implementation, the invention provides a method of processing a digital image that is to be printed on a surface of an identification document as a fluorescing-capable image to improve the quality of the image. Edges or boundaries are detected within the image, the detected edges or boundaries forming an intermediate image. The edges or boundaries within the image are emphasized, and the emphasized image is used for printing the covert image. In some implementations of the invention, a digital watermark is embedded in the covert image.

Abstract: A system for distributing auto-stereoscopic images, a parallax blocking mask and methods for producing a parallax blocking mask. A parallax blocking mask is provided as an “add-on” for an existing image display device having a flat panel type display screen. The mask is tailored to the needs of the existing device and delivered to a remote user of the display device. The user mounts the mask to the display device so that the mask overlies the display screen. 3D content in the form of composite stereoscopic images derived from one or more stereoscopic image pairs, and application software, are downloaded to the display device over the Internet, and the application software interleaves the composite stereoscopic images for display on the display screen while the mask is in place. Use of a parallax blocking mask having variable edge transitions, a duty cycle less than fifty percent, or both, is disclosed.