Abstract: This invention is a method of producing a set of TRC's for a color printer's secondary halftone screens that is correlated with the printer's primary halftone screens. The method makes use of the printer/screen characteristic data that is normally gathered during screen calibration. However, instead of progressing from the data to a normal calibration for the secondary screens, the method goes backward through the data starting with the finished primary screen TRC's. The method insures that for every primary screen density, the closest possible secondary screen density is used when the same digital value is specified.

Abstract: A method of correction for toner misregistration in color printing systems, specifically for run length encoded image data. This method, called “trapping”, usually involves extending the color separations one or more pixels to overlay the edge. The color of the “trap zone” is chosen such that it is nearly imperceptible in the presence of the two initial colors. Our approach assumes the existence of a “trap generator”, which provides a trap color given two input colors. In run length encoded image format, the image is comprised of an array of “scanlines”, consisting of a string of “runs” that are specified by a minimum position in the fast (horizontal) direction, a length, and a color. We describe a method of trapping involving the following steps: 1) inspecting the run lengths in each scanline to determine the color edges of the image; 2) sending the colors at the boundaries to the trap generator to determine the trap color; and 3) modifying the intersecting runs with the trap color.

Abstract: A method for correcting a white line artifact between low and high frequency printed pixels. A printer may be able to print either a high or low frequency halftone pixels in some locations, but may be able to print only high frequency halftone pixels in other locations, the latter known as out of phase locations. If the image data is in run length encoded form, and the printer tries to print a low frequency pixel in an out of phase location, no pixel will be printed in that location and a white space results. The remedy is to test at the beginning and end of low frequency runs bordering high frequency runs. If the first (last) low frequency pixel of an original run is in an out of phase location, a one pixel run of the high frequency screen and of the low frequency color is added before (after) the original run, and the run length of the low frequency run is decreased by one pixel.

Abstract: 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, &Dgr;a*, (or &Dgr;b*) 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 &Dgr;a*n; and adding the value of &Dgr;a*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 &Dgr;a* 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(&Dgr;a*n).

Abstract: Structuring a raster image data file includes accessing image data containing set-up information and image data, determining a structure of the image data, sequencing contents of the image data file such that different parts of the set-up information are grouped together, segmenting the image data, and constructing an output image data file. The structure of image data may include one or more layers. The set-up information may be sequenced to precede the image data. Therefore, segmented image data can be distributed to more than one processor and sequentially processed and reproduced. This results in shortening the printing time.

Abstract: A method and apparatus for compressing and decompressing electronic documents, with maximum intradocument independence, and maximum flexibility in optimization of compression modes. The method includes receiving documents containing unknown combinations of a plural data types, including combinations of scanned data, computer rendered data, compressed data and/or rendering tags; dividing the received image into strips of blocks determining from the image itself, which data types are present in each block; compressing data of each data type present in each block with a compression method optimized for its data type. Scanned data may be further segmented into plural scanned data types, where each data type is compressed in said compressing data step with a compression method optimized for said scanned image data type.

Abstract: 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.

Abstract: A method of correction for toner misregistration in color printing systems, specifically for run length encoded image data. This method, called “trapping”, usually involves extending the color separations one or more pixels to overlay the edge. The color of the “trap zone” is chosen such that it is nearly imperceptible in the presence of the two initial colors. Our approach assumes the existence of a “trap generator”, which provides a trap color given two input colors.

Abstract: An object optimized printing system and method includes 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 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, 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 IOT 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.

Abstract: Every printing system has characteristic defects which detract from high quality printing. Xerographic printing systems show defects such as banding, mottled colors in large fill areas, trail-edge deletion and starvation where toner concentrations drop at certain color edges, misregistration, and so on. Ink jet printing systems can show ink bleeding, streaking in the direction of head movement, and so on. One approach to reducing printer defects is to refine the electro-mechanics for more precise printing. Another approach which works for predictable defects is to modify the digital data being sent to the printer to pre-compensate for the defect. The prior art does this to a limited extent for individual object types (strokes, fills, images, text, etc.) and for misregistered color edges (trapping). This invention extends the range of edge-related defects that can be both predicted and pre-compensated for.

Abstract: 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.

Abstract: 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.

Abstract: A run length codeword system which has a set of codewords, each codeword being one byte. The first codeword of a run is divided into a 4-bit code part and 4 bits of printing hints. The code part specifies the source of the data, and the format of the remaining bytes in the run. The remaining one or two codewords specify the number of remaining data bytes in the run, or color values.

Abstract: A run length codeword system which has a set of codewords, each codeword being one byte. The first codeword of a run is divided into a 4-bit code part and 4 bits of printing hints. The code part specifies the source of the data, and the format of the remaining bytes in the run. The remaining one or two codewords specify the number of remaining data bytes in the run, or color values.

Abstract: A method and apparatus for compressing and decompressing electronic documents, with maximum intradocument independence, and maximum flexibility in optimization of compression modes. The method includes receiving documents containing unknown combinations of a plural data types, including combinations of scanned data, computer rendered data, compressed data and/or rendering tags; dividing the received image into strips of blocks determining from the image itself, which data types are present in each block; compressing data of each data type present in each block with a compression method optimized for its data type. Scanned data may be further segmented into plural scanned data types, where each data type is compressed in said compressing data step with a compression method optimized for said scanned image data type.

Abstract: A method of determining whether a page to be printed on a color printer will actually be entirely printed in one colorant, usually black, and if so, automatically omitting whatever processing steps are unnecessary as a result. Determining if the page is monochrome can be done either by (1) including a signal in the PDL or by a signal from the user or by (2) inspecting each element of the page to determine if all elements are specified to be printed in the same one colorant. If either is true, then various color operations such as trapping, color conversion to any other color, and color correction for non-selected colors can be automatically omitted.

Abstract: 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.

Abstract: A simple method of anti-aliasing for edges near the fast scan direction is to replace the pixels on both sides of the transition in a scan with pixels of varying intermediate color. Thus, if there is an edge between red and blue areas, instead of there being an abrupt change from red to blue at the edge, there will be a number of pixels that slowly vary from mostly red to mostly blue, which will tend to make the jagged edge less obvious.

Abstract: 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.

Abstract: An object optimized printed system includes an image output terminal controller. The system inputs a print file defining a plurality of pages in a 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 system automatically generates rendering tags for each of the objects. The rendering tags are used to control 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 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.