Abstract: A method and apparatus for the control of darkness/lightness in a digital image rendered by a printing system. The technique preferably employs templates to selectively apply different amounts of darkening (lightening) to borders of structures detected within the image dependent upon the need for darkening (lightening).

Abstract: A system for providing an output from a digital printing apparatus which is of higher resolution than the native resolution of the original image data. For a given center pixel area, image data corresponding to pixel areas generally neighboring the center pixel area are attempted to be matched to various templates which are consistent with curved lines in which resolution enhancement of the center pixel would be desirable. In a second stage of template matching, a second set of image data, corresponding to pixel areas further away from the center pixel than the first set of pixel areas, is also attempted to be matched to templates. The second stage of template matching helps to avoid resolution enhancement of image data which is related to a halftone image.

Abstract: A lead edge lightening circuit which will lighten a scan line based on a seven by seven pixel area surrounding the current pixel. The area is divided into four sub-areas, each of four by four pixels, and each having the current pixel at one corner. Each sub-area is summed and compared to a threshold number. If the threshold number is equalled or exceeded by at least one of the four sums, an overlay bit, which can be white or black, is output. The current pixel is replaced by a white pixel if a white pixel has been output, otherwise the current pixel remains unchanged.

Abstract: A method is shown to enable the conversion of binary image data originally generated at a first resolution into representative binary image data of an integer-value magnified resolution. Included within the resolution conversion method are methods which tend to smooth transitional edges, compensate for the conversion of an image optimized for write-black printing system to a write-white printing system, and improve the rendition of graphics images and reverse printing.

Abstract: An image compensation system which provides dilation or erosion of image features using halfbitting or fullbitting in the rendition of bitmap images, especially on a write-white printer. A region of pixels of an image is isolated which includes two or more correctable pixel locations. A set of state determination rules, based on the formation of pixels in the isolated region, is used to determine a corrected binary pixel state for each of the correctable pixels. Corrections for one correctable pixel may be considered in the state determination rules for adjacent correctable pixels. A single enhanced output pixel is provided for each image input pixel, thereby preserving the original image resolution. Performing enhancements on multiple input pixels simultaneously increases the system throughput.

Abstract: The present invention is a method to enable the conversion of binary image data originally generated at a lower resolution into representative binary image data of a higher resolution, wherein the conversion ratio, or magnification factor, is an integer value. Included within the resolution conversion method is compensation for the conversion of an image optimized for write black printing system to a write white printing system.

Abstract: A printing machine having an imaging surface, a scanning system for modulating a beam and scanning an image onto the imaging surface, a device to designate a variable relative darkness factor, a store for holding a partial array of the image to be reproduced, a comparator for relating the partial array of the image to be reproduced with standard reference formats to produce correlation signals, modulating logic responsive to the correlation signals and the variable relative darkness factor to provide timing adjustments and a modulator for modulating the beam and scanning the image onto the imaging surface in response to the timing adjustments.

Abstract: A method for enhancing the contour fidelity of printed images of two or more colors is described, which includes obtaining a digital representation of the color image and finding color separations of each color. Each color separation is enhanced by a single set of inverse symmetrical templates, the set including templates in which the second template is always the inverse of the first, and the third and fourth templates are 180 degree rotations of the first two. The resulting smoothed color separations are recombined into an enhanced image without separation error.

Abstract: A method for converting binary image data originally generated at a lower resolution into representative binary image data of a higher resolution, wherein the conversion ratio, or magnification factor, is an integer value. Also included are methods for smoothing the interpolated output image and thereby reducing objectionable visual characteristics observable in digitally encoded data using conventional magnification techniques.

Abstract: Gray level pixel values in an image, each pixel value represented by c levels are quantized by applying a threshold level to each pixel value in the image to produce a pixel value having d levels, and applying a weighted portion of the value of the difference (the "error") between the pixel value and the thresholded value to a predetermined set of neighboring pixels; for each neighboring pixel in the predetermined set to which the error term is to be applied, comparing the value of the neighboring pixel to each possible legal output value, and if any pixel value the predetermined set of neighboring pixels is equal to one of the legal output values, then the error term is not applied to that term, and is applied to remaining non-legal values. If all the neighboring pixels have legal values, a decision is made based on a look-ahead neighborhood (a set of pixels used to determine the fractional error allocation) as to whether the error term is discarded or preserved.

Abstract: A one dimensional electronic halftone generating system having a source of digital data representative of pixel greyscale, a counter to store the digital data, and pulse producing logic responsive to the counter to activate a laser modulator in accordance with the digital data representative of each pixel. In particular, a six bit data word represents one of 64 greyscale states for a particular pixel. The pulse producing logic responds to the particular data word to produce a pulse of a given duration or width to drive the laser for a given time period. The duration of the pulse, representing one to 64 states for a given pixel, will produce a given discrete greyscale value for each pixel.

Abstract: Positive form overlays are used to make composite images with a positive mode xerographic printer having a laser scan exposure mechanism. The laser scan or electronic exposure mechanism uses an oscillating galvanometer mirror to sweep a scanning spot over a cylindrical shape photoconductor. The xerographic processor includes a transfer drum able to recycle a sheet relative to the photoconductor to transfer at least two sequentially generated xerographic toner images to the same side of the same support in registration. One image is made in response to electronic signals and the other from the positive overlay thereby yielding a composite toner image.

Abstract: Reproductions of originals are obtained electro-photographically by exposing a charged photoconductor sequentially to at least two electro-optically regulated laser beam exposures, each exposure representing a separate color component of the original. Full color reproduction is possible.Alternatively a laser beam exposure may be accompanied, preferably substantially simultaneously, by exposures from either an opaque original or a transparency or both.

Abstract: An electrostatographic printing machine in which a plurality of transparencies are reproduced. The transparencies are stored in an ordered sequence and advanced automatically into communication with the reproduction system so as to form ordered sets of copies thereof.

Abstract: An electrostatographic printing machine in which a plurality of transparencies and at least one opaque original document are reproduced. The transparencies are stored in an ordered sequence and advanced automatically into operative communication with the reproduction system. After a pre-determined number of transparencies have been copied, the opaque original document is reproduced to form an ordered set of copies having copies of the transparencies and opaque original documents.

Abstract: A half-tone screen in which a substantially transparent substrate has a plurality of opaque regions disposed thereon. The opaque regions are arranged in at least a high frequency repetitive pattern and a low frequency repetitive pattern. This type of screen may be employed to modulate the light image of a color transparency being reproduced by an electrophotographic printing machine.

Abstract: An electrophotographic printing machine in which color transparencies are reproduced. A projected image of the color transparency is scanned forming a light image thereof. The light image is modulated and filtered creating a single color half-tone light image. A charged photoconductive member is irradiated by the single color half-tone light image recording a single color electrostatic latent image thereon.

Abstract: An electrophotographic printing machine in which color transparencies are reproduced. A projected image of the color transparency is scanned forming a light image thereof. The light image is modulated and filtered creating a single color half-tone light image. A charged photoconductive member is irradiated by the single color half-tone light image recording a single color electrostatic latent image thereon.

Abstract: An electrophotographic printing machine in which color transparencies are reproduced. A projected image of the color transparency is scanned forming a light image thereof. The light image is modulated and filtered creating a single color half-tone light image. A charged photoconductive member is irradiated by the single color half-tone light image recording a single color electrostatic latent image thereon.

Abstract: An electrophotographic printing machine in which color transparencies are reproduced. A projected image of the color transparency is scanned forming a light image thereof. The light image is modulated and filtered creating a single color half-tone light image. A charged photoconductive member is irradiated by the single color half-tone light image recording a single color electrostatic latent image thereon. A light image of a composition frame forming an opaque border extending outwardly from the single color half-tone light image of the transparency is projected onto the charged portion of the photoconductive member in registration with the single color electrostatic latent image recorded thereon to form a combined electrostatic latent image. The combined electrostatic latent image is developed with toner particles complementary in color to the color of the single color light image. The toner powder image is transferred to a sheet of support material and permanently fused thereto.