Hewlett-packard Company

Hewlett-packard Development Company, L.P.

Hewlett-packard Corporation

Mark A Overton

Matthew Grant Lopez

Alan Eddy Cariffe

Michael S Gray

Steven Wayne Hendrix

Long C Doan

Anne P Kadonaga

Iue-Shuenn Chen

David Charles Towery

Janet E Mebane

Mathew G Lopez

Neil F Bankston

A motor configured to selectively drive a carriage and document transport. A single imaging element is used to provide a dual function of detecting conveying sheet as it approaches platen and to perform imaging of the sheet.

Document transport

A method of an embodiment of the invention is disclosed that determines calibration factors for a fluid-ejection mechanism that is capable of ejecting differently colored fluids onto media. The energy used to eject fluid for each of at least one of the fluid colors is adjusted based on the calibration factors, so that fluid drop ejections of the fluid colors yield fluid drop masses having a consistent ratio.

Adjustment of fluid-ejection energy to yield fluid drop masses having consistent ratio

An exemplary method, which can be used to reduce errors related to pen-to-pen misalignment and/or paper-shape variation, entails changing the drop-ejection velocity of an ink-jet pen.

Changing drop-ejection velocity in an ink-jet pen

A noise reduction system and method for reducing unwanted noise in digital data is disclosed. The system and method includes a noise reduction module having a noise estimation and reduction submodule. The noise estimation and reduction submodule can be any suitable submodule for receiving compressed data, estimating the amount of noise added due to data compression, and using the estimate to reset false gray pixels, thereby producing new data with reduced halos.

System and method for reducing unwanted noise in digital data

In a preferred method for horizontal down-scaling of a pixel pattern, the down-scaling is performed on a byte-by-byte basis along each row of pixels. To avoid loss of information, if a pixel to be deleted is black and the black pixel has two original white immediate neighbors, the pixel to the right of the black pixel to be deleted is set to black. Each byte may be processed independently from the other bytes. In a preferred method for vertical down-scaling of a pixel pattern, a pixel row to be deleted, to achieve the desired down-scaling, is identified. To avoid loss of information, pixels in a byte of pixels in the row to be deleted are bit-wise logically OR'd with the corresponding pixels in the next row, and the OR'd values replace the pixels in that next row. Changing the pixel values during the horizontal or vertical down-scaling is only performed if it is determined that the byte is part of text and not part of a picture. In the preferred embodiment circuit, look-up tables are used which receive the original bytes as addresses and output the horizontally down-scaled pixels. A look-up table may also determine if the byte is part of text or part of a picture. The total memory capacity required for the circuit is small compared to the prior art, and the processing is fast.

Down-scaling technique for bi-level images

An improved method for providing a more faithful and pleasing rendition of a pixel pattern is described herein. This method first places the original pixel pattern in a bit mapped memory. A small portion of this bit mapped pattern, called an input tile, acts as an address for a look-up table containing a corrected pixel pattern portion (an output tile) corresponding to the target pixels to be corrected in the input tile. To derive the output tiles stored in the look-up table, a high resolution bit map is created from an input tile by scaling the input tile. A triangular portion of each convex corner in the high resolution bit map is chopped off, and a triangular portion of each concave corner in the high resolution bit map is filled in. The resulting pattern is then smoothed using a low pass filter. The size of these triangular portions and the extent of low pass filtering are determined using a function based on the vulnerability of a pixel to being eliminated during the above smoothing process. This regulation of smoothing helps preserve desired detail in the image. The middle portion of the high resolution bit map corresponding to the two original target pixels intended to be corrected is then divided up into a number of pixel areas, where each area represents a pixel to be printed. A threshold number is then compared to the pixels in each area, and a corresponding output pixel is then stored, printed, or otherwise displayed.

Pixel correction and smoothing method

Techniques are disclosed for depleting raster data to allow printing of the depleted raster data on a grid that corresponds to the resolution of the undepleted raster data with a printed dot size that is larger that would otherwise be utilized with the undepleted raster data and to achieve faster ink dry time. Also disclosed is a technique for up scaling raster data at a particular resolution (e.g., 300 dpi) to a higher resolution in such a manner that expanded data includes a greater number of dot producing pixels to compensate for a dot size that is larger than the dot size that is appropriate for the higher resolution, and does not require horizontal depletion for printing with such dot size. This allows raster data at a particular resolution to be combined with higher resolution rasterized vector data for printing in accordance with the enhanced mode of operation.

Double axis dot depletion for 600 DPI edge acuity with 300 DPI print

An improved method for providing a more faithful and pleasing rendition of a pixel pattern is described herein. This method first places the original pixel pattern in a bit mapped memory. A small portion of this bit mapped pattern, called an input tile, acts as an index for a look-up table containing a corrected pixel pattern portion (an output tile) corresponding to the target pixels to be corrected in the input tile. This process may also be performed using an algorithm. To derive the output tiles, a high resolution bit map is created from an input tile. A triangular portion of each convex corner in the high resolution bit map is chopped off, and a triangular portion of each concave corner in the high resolution bit map is filled in. The resulting high resolution bit map is then filtered using a low pass filter. The size of these triangular portions and the extent of filtering are determined using a function based on the vulnerability of pixels to being eliminated during the above smoothing process. The middle portion of the high resolution bit map corresponding to the two original target pixels intended to be corrected is then divided up into a number of pixel areas, where each area represents a pixel to be printed. A threshold number is then compared to the pixels in each area, and a corresponding output pixel is then stored, printed, or otherwise displayed.

An improved method for providing a more faithful and pleasing rendition of a pixel pattern is described herein. This method first places the original pixel pattern in a bit mapped memory. A small portion of this bit mapped pattern, called an input tile, acts as an index for a look-up table containing a corrected pixel pattern portion (an output tile) corresponding to the target pixels to be corrected in the input tile. The corresponding output tile is then printed or otherwise displayed at a higher dots-per-inch (dpi), in both the horizontal and vertical directions, than the original pixel pattern to provide a corrected and higher resolution pattern. This process may also be performed using an algorithm which performs a correction on the target pixels in the input tile to generate an output tile instead of indexing a corresponding output tile in a look-up table. If the original pixel pattern is detected to be part of an image, as opposed to text, no correction of the pixel data is made. The preferred method also detects input tile exceptions which are not subject to the normal corrections performed on the other input tiles. Such an exception may be the detection of a stray dot or a notch or tick in a line of pixels. These exceptions are then corrected accordingly.

Pixel correctional and smoothing method

An improved method for providing a more faithful and pleasing rendition of a pixel pattern is described herein. This method first places the original pixel pattern in a bit mapped memory. A small portion of this bit mapped pattern, called an input tile, acts as an address for a look-up table containing a corrected pixel pattern portion (an output tile) corresponding to the target pixels to be corrected in the input tile. To derive the output tiles stored in the look-up table, a high resolution bit map is created from an input tile by scaling the input tile. The resulting pattern is then smoothed using a filter. The middle portion of the high resolution bit map corresponding to the two original target pixels intended to be corrected is then divided up into a number of pixel areas, where each area represents a pixel to be printed. A threshold number is then compared to the pixels in each area, and a corresponding output pixel is then stored, printed, or otherwise displayed.

A technique for rasterizing a line having a predetermined width and slope, including the step of providing stored data associated with predetermined slopes and widths of lines, such data including information indicative of raster data for portions of lines of the predetermined slopes and widths. The stored data associated with the slope and width of the line to be rasterized is accessed, and raster data for one of predetermined portions of the line to be rasterized is generated from the accessed data, wherein the predetermined portions collectively form the line to be rasterized. The generated raster data is copied to a bitmap memory, and the steps of generating and copying raster data are repeated until the entire line has been rasterized.

Growing community of inventors

Escondido, CA, United States of America

Mark A Overton