Abstract: A method of correcting color shifts produced by improper imaging in a natural scene image including the steps of: converting an electronically encoded natural scene image described in terms of red-green-blue color space to electronic encoding terms of luminance, chrominance color space; sorting each luminance signal forming the image into one of a plurality of predetermined luminance magnitude bands; for each luminance magnitude band, calculating the band average chrominance signal of each pixel in the band to determine the relative amounts of each color in the band; for each band average chrominance signals, averaging the band average chrominance signals over a subset of the luminance magnitude bands to derive an interband average chrominance value; comparing each interband average chrominance value with neutral gray color to determine a correction signal; for each luminance magnitude band, adding the correction signal to the color of each pixel in the band.

Abstract: In an electrophotographic imaging device, in which an electrostatic image is formed and developed on a first support to form a toned image, and the toned image is transferred to a second support substrate and subsequently to a final support, and in which to form color images, a succession of toner images are superposed on each other by transfer from one or more first support to the second support, transfer efficiency is enhanced and color consistency is improved by providing an order of superposition which places the toner having the greatest residual mass/area dependent color instability in a position of being sandwiched between or protected by two or more other toner images whose color contribution to gray balance is not as greatly dependent on mass per unit area. Thus, during transfer, the sandwiched or middle layer(s) will retain integrity.

Abstract: A method and arrangement for quantization of the nth pixel in scan line l (i.e., pixel n,l), with error diffusion to a matrix including pixels at pixel locations corresponding to pixels {(n+1,l), (n-2,l+1), (n-1,l+1), (n,l+1)}. Distribution weighting may be in accordance with the scheme {(n+1,l)=0.5, (n-2,l+1)=0.125 (n-1,l+1)=0.125 (n,l+1)= 0.25 }. In another embodiment, distribution weighting may be in accordance with the scheme {(n+1,l)=0.5, (n-3,l+1)=0.0625, (n-2,l+1)=0.0625, (n-1,l+1)=0.125, (n,l+1)=0.25, }.

Abstract: A method of improving processing of a color natural scene image defined by color density signals processed by multiple processing elements, wherein after an exposure processor incorporates a luminance signal histogram, a modifying TRC curve is derived and applied to the luminance histogram signal. The resultant modified luminance histogram signal is blurred prior to directing it to a contrast processor. The modifying TRC curves determined at each processor are combined and applied to the color density signals only after combination.

Abstract: Method and apparatus for processing color document images to determine the presence of particular image types in order to designate areas for optimal image processing thereof. A multi-separation image defined in terms of color density for each separation is converted to a luminance-chrominance definition, where one component of the image represents image intensity. An image segmentation process operates on the image intensity signal, the results of which are used to determine processing of the multi-separation image.

Abstract: An electrophotographic device for reproducing an image on an imaging member includes: processing elements for forming a toner-developed latent image on a charge retentive surface of the imaging member; a transfer station for transferring toner from the imaging surface to a second surface of a receiving member; an arrangement for enhancing toner release from the imaging surface, including a resonator in contact with and applying vibratory energy to the imaging member at a location at which toner release is desired having a resonator resonant frequency f.sub.r ; a coupler for coupling the imaging member to the resonator; a driving signal source electrically coupled to the resonator, and producing a driving signal selected to drive the resonator at frequency f.sub.r ; the imaging member, coupler and receiving member together defining a system having a first and second belt resonant frequency (f.sub.b1 and f.sub.

Abstract: In conjunction with an image segmentation arrangement, in which the image is processed with an image type detection arrangement, the output of which controls an image processing of the image, there is provided a morphological filtering operation, which initially provides a noise removal filter operating on the image detection signal, to remove noise within an area of the image detection signal, and subsequently provides hole filling filter, which bridges small gaps in the image type detection results.

Abstract: An ionographic printing system including an imaging member with a charge retentive surface on which a latent image may be formed; a printhead including a source of ions, means for moving ions from the source to the charge retentive surface in a continuous stream, and means for modulating the stream in accordance with a desired image; and in which a projection field between the charge retentive surface and the printhead tends to focus ions in a manner reducing spread in directions parallel and anti-parallel to the process direction, there is provided means for defocusing and slightly repositioning the ion stream including an additional pair of electrodes arranged adjacent to the ion stream and an A.C. voltage source with time dependent bias, to apply an A.C. field across the ion stream at a frequency selected to sweep the ion stream in two directions parallel and anti-parallel to the process direction of the device.

Abstract: A method of quantizing pixels in an image formed by a plurality of pixels, each pixel representing an optical density of the image at a location therewith, and having an original optical density value selected from one of a set of `c` original optical density values that has a number of members larger than a desired output set of `d` optical density values, through a process of error diffusion. In this process, `c` and `d` are integer values representing pixel depth. For an input image so comprised, initially, an image signal is initially modified in accordance with previously determined error. Thereafter, during the quantization step of the process, the threshold of an error diffusion process is dynamically adjusted in accordance with the original image to selectively control an amount of edge enhancement introduced into the image.

Abstract: A method of compressing an original document image in a manner assuring a minimum compression ratio includes the steps: a) storing to a tile memory a portion of the document image; b) from the document image portion stored in tile memory, using the discrete cosine transform a basis function (DCT), forming a frequency space representation of the image at a transformer; c) retrieving a set of stored values referred to as a Q-Table, d) dividing each of the Q-Table values into the DCT value, and returning the integer portion of the value as the quantized DCT value; e) encoding the quantized DCT values using a statistical encoding method; f) determining whether the data block size is larger than desired, and if not, passing the data block to an output; g) otherwise, reducing a least one high frequency component of the frequency space representation of the document image and and repeating steps e)-g) until the size of the data block is acceptable.

Abstract: A method of quantizing pixel values in an image formed by a plurality of pixels, each pixel representing an optical density of the image at a location within the image, and having an original optical density value selected from one of a set of `c` original optical density values that has a number of members larger than a desired output set of `d` optical density values through a process of combined halftoning and cell-to-cell error diffusion. Initially, each pixel is modified with a pro rata portion of an error term determined for a previous halftone cell, or from the current cell in a previous interaction. A set of modified pixels, corresponding in position to an m.times.n halftone cell, are processed in accordance with a standard halftoning process, to derive a set of output pixels at one of d optical density levels.

Abstract: A method and arrangement for the application of under compensated error diffusion to a pixel quantizing method in the conversion of image data from a number of input levels that is relatively large with respect to a number of desired output levels.

Abstract: In an image input terminal for deriving an electronic representation of the image, including a platen for supporting a document to be scanned, a scanning system including an illumination source for illuminating a document supported on the platen, an array of photosensitive elements which produce an electrical response to sensed reflected light, an arrangement for directing light reflected from a document to the linear array, and an arrangement for providing relative motion in a slow scan direction between the linear array of photosensitive elements and the document, there is provided an arrangement for rotating the scanning system of photosensitive elements and an illumination source about a rotational axis, by an amount corresponding to detected skew of the image, so that, upon relative movement of the linear array of photosensitive elements and the document, the effects of skew in the slow scan direction are removed from the electronic representation of the image.

Abstract: In a printer which produces images as a function of the combination of cyan (C), magenta (M), yellow (Y) and black (K) colorants on an output color print, responsive to device independent colorimetric description of an image, there is provided a method of calibrating the response of the printer to an image described in terms of colorimetric values, including the steps of first, gray balancing or linearizing colorant signals; secondly, adding black to an ideal device dependent description of a color image in accordance with a predetermined black addition process, and thirdly, providing a color correction transformation process, where the color correction transformation is accomplished via a method of interpolating printer responses from a look-up table indexing colorimetric descriptions of measured real responses, which take into account subsequent black addition and signal linearization.

Abstract: An electronic printing system having an image input for receiving digitally represented images from a source of input information such as an image input scanner; a controller having the capability of rotating an image in at least 90.degree. increments and which can provide such rotation in accordance with a pre-programmed set of commands; a user interface, connected to the controller, and for directing information about the orientation of the input image, and information about output orientation and placement in accordance with one of a plurality of selectable output orientation; and an output, such as a binary printer, to which the controller may direct reoriented image data.

Abstract: A method is provided for increasing resolution of an input image in an input bitmap while performing a density preserving smoothing operation. The input bitmap includes a first set of pixels K.times.L.times.b, and the method comprises the following steps: (a) mapping the first set of pixels into a second set of individual pixels .kappa.K.times. .lambda.L.times.

Abstract: Method and apparatus for processing image pixels to determine the presence of high frequency halftone images. Prior to auto correlation, each pixel in the image is examined to determine whether it is a local area maximum or minimum. A binary image function composed of the image local area maximum or minimums is made available for auto correlation. The presence of peaks at shifts indicative of predetermined halftone image frequencies is detected, and an output signal indicative of the presence or absence of peaks at the predetermined halftone image frequencies is provided. The arrangement is combined with a run length encoder to reduce false microdetection results.

Abstract: A method for varying the color of an image including lines and background. Where the image includes the colors black and white and a plurality of gray pixels, where gray refers to the presence of pixel values between the maximum and minimum pixel values, inclusive, the image is first converted to a color space, such as for example, r, g, b (red-green-blue). Pixel values are thresholded for differentiation between lines and background. When pixels have a value indicating that the pixel is background, that pixel is set to a background color that has been previously selected. Otherwise, that pixel is set to a foreground color. The result is that background is set to a single color, and lines are set to a second color. Alternatively, where intermediate values are present, the foreground color value may be added to the intermediate level color value to produce a gradually varying colored line.

Abstract: An electrophotographic device having an imaging member with a charge retentive surface, driven along an endless path through a series of processing stations that create a latent image on the charge retentive surface, develop the image with toner, and bring a sheet of paper or other transfer member into intimate contact with the charge retentive surface at a transfer station for electrostatic transfer of toner from the charge retentive surface to the sheet. For the enhancement of toner release from a surface at any of the processing stations, a resonator suitable for generating vibratory energy is arranged in line contact with the back side of the non-rigid member, to uniformly apply vibratory energy thereto.