Halftone computer imager

A method for generating signals indicative of a sequence of page images included in a document, each of said page images having zero or more character, graphic or image elements, said page including a plurality of halftones cells having one or more pixels, said method comprising the steps of:

• executing a document signal file corresponding to the sequence of page images to generate an intermediate executable signal file having therein signals corresponding to at least one of said pages of the document that is rotation and position independent,
• generating identification signals identifying each element as being a character, graphic or image type element;
• generating, for each page, display list signals indicative of element parameters for each element on said page;
• generating compressed element signals in accordance with said identification signals with each of said elements being compressed in accordance with its identified element type,
• generating character cache signals corresponding to compressed elements identified as characters,
• generating signals corresponding of a list of compressed characters,
• generating signals corresponding to compressed graphic elements including a scanline directory having an ordered list of signal pointer signals indicative of which scanlines have a graphic element and marker signals indicative of blank and duplicate scan lines in said graphic element,
• generating signals corresponding to compressed image elements with each compressed image element having an lateral (X), vertical (Y) extent on the page and signals corresponding to color,
• generating signals corresponding to intermediate "image ink" marker signals which point to signals stored in memory corresponding to the scanline image data signals for that marker signal;
• decompressing received signals corresponding to compressed character elements,
• decompressing signals corresponding to compressed graphics and image elements;
• merging decompressed character, graphic and image signals and, if two of said element types are designated for a given pixel, selecting which of said character signals or said graphics signals is to be written for said pixel and suppressing non-selected signals;
• generating at least one signal set indicative of the intensity magnitude of the pixels included in each of said halftone cells;
• sampling output signals at each pixel location and providing signals of a selected dot shape,
• converting the current pixel position on a page to a position in a halftone space scaled therefrom, and
• comparing the intensity requested from the rasterizer decompression unit with the intensity of the current pixel received from the dot function generator;
• and
• generating signals enabling said current pixel should said requested intensity exceed a threshold value, thereby providing to an output imaging device signals indicative of a selected intensity.

A method for generating signals indicative of a sequence of page images included in a document, each of said page images having at least one character, graphic or image element, said page including a plurality of halftones cells having one or more pixels, said method comprising the steps of:

• executing a document signal file corresponding to the sequence of page images to generate an intermediate executable signal file having therein signals corresponding to at least one of said pages of the document that is rotation and position independent,
• generating identification signals identifying each element as being a character, graphic or image type element;
• generating, for each page, display list signals indicative of element parameters for each element on said page;
• generating compressed element signals in accordance with said identification signals with each of said elements being compressed in accordance with its identified element type,
• generating character cache signals corresponding to compressed elements identified as characters,
• generating signals corresponding of a list of compressed characters,
• generating signals corresponding to compressed graphic elements including a scan line directory having an ordered list of signal pointer signals indicative of which scanlines have a graphic element and marker signals indicative of blank and duplicate scan lines in said graphic element,
• generating signals corresponding to compressed image elements with each compressed image element having an lateral (X), vertical (Y) extent on the page and signals corresponding to color,
• generating signals corresponding to intermediate "image ink" marker signals which point to signals stored in memory corresponding to the scan line image data signals for that marker signal;
• decompressing received signals corresponding to compressed character elements,
• decompressing signals corresponding to compressed graphics and image elements;
• merging decompressed character, graphic and image signals and, if two of said element types are designated for a given pixel, selecting which of said character signals or said graphics signals is to be written for said pixel and suppressing non-selected signals;
• generating at least one signal set indicative of the intensity magnitude of the pixels included in each of said halftone cells;
• sampling output signals at each pixel location and providing signals of a selected dot shape,
• converting the current pixel position on a page to a position in a halftone space scaled therefrom, and
• comparing the intensity requested from the rasterizer decompression unit with the intensity of the current pixel received from the dot function generator;
• and
• generating signals enabling said current pixel should said requested intensity exceed a threshold value, thereby providing to an output imaging device signals indicative of a selected intensity.

In a computer imaging system for use in generating signals indicative of an overall image having zero or more character elements of a plurality of pixels, the system having a controller for receiving command signals indicative of parameters of the image and generating therefrom imposition signals for configuring the image in a selected sequence and orientation for presentation to an output imaging device, an interpreter adapted to receive signals corresponding to the image, the interpreter having an identifying means for generating signals identifying therefrom pixel signals corresponding to characters, a rasterizer having a compressor means for generating character cache signals corresponding to said characters, a means for generating signals corresponding of a list of characters, the system comprising:

• a graphics accelerator means for receiving signals from said rasterizer and generating therefrom signals for use by the output imaging device for imaging the image on a medium, said graphics accelerator means including,
• a character decompressor means for use in decompressing signals corresponding to compressed characters received from said rasterizer,
• a Z eliminator means receiving signals from said character decompressor means corresponding to decompressed image signals including signals indicative of said characters, said Z eliminator means merging said received decompressed image signals and, if two of said decompressed image signals are designated for a given pixel, selecting which of said decompressed image signals are to be written for that pixel and suppressing non-selected signals for that pixel;
• and
• an intensity map generator means for generating at least one signal set indicative of the intensity magnitude of each of the pixels.

A halftone computer imaging system for use in generating signals indicative of a sequence of page images included in a document, each of the page images having zero or more character, graphic or image elements, the page images further including a plurality of halftone cells having one or more pixels, the system having a controller for receiving command signals indicative of parameters of said page images and generating therefrom imposition signals for configuring said page images into a selected sequence of page images and orientation for printing on one or more printing plates;

• an interpreter adapted to receive document :
• signals from the controller corresponding to said sequence of page images, the interpreter including an identifying means for generating signals identifying each element as being a character, graphic or image type element;
• a means for generating, for each page, display list signals indicative of element parameters for each element on said page;
• a rasterizer having a compressor for generating compressed element signals in accordance with said identifying means signals with each of said elements being compressed in accordance with its identified element type;
• a means for generating character cache signals corresponding to compressed elements identified as characters, a means for generating signals corresponding to a list of compressed characters, a graphics compressor means for generating signals corresponding to compressed graphic elements including a scanline directory having an ordered list of signal pointer signals indicative of compressed representations of the scanlines and marker signals indicative of blank and duplicate scanlines in said graphic element, an image compressor means for generating signals corresponding to compressed image elements with each compressed image element having a lateral (X), vertical (Y) extent on the page and signals corresponding to color, said image compressor means further for generating signals corresponding to intermediate "image ink" marker signals which point to signals stored in memory associated with said system corresponding to the scanline image data signals for that marker signal;
• said system comprising:
• a graphics accelerator means for receiving signals from said rasterizer and generating therefrom signals for use by an output imaging device for imaging said page images on a medium, said graphics accelerator means including
• a character decompressor means for use in decompressing signals corresponding to compressed characters received from said rasterizer, and
• a graphics decompressor means for use in decompressing signals corresponding to compressed graphics and image elements received from said rasterizer;
• a Z eliminator means receiving signals from said character decompressor means corresponding to decompressed signals indicative of said character elements and receiving signals from said graphics decompressor means corresponding to said graphics elements and said image elements, said Z eliminator means merging said received decompressed character, graphic and image signals and, if two of said element types are designated a given pixel, selecting which of said decompressed character signals or said decompressed graphics signals are to be written for said pixel and suppressing non-selected signals;
• an intensity map generator means for generating at least one signal set indicative of the intensity magnitude of the pixels included in each of said halftone cells;
• and
• a halftone signal generator means for providing to the output imaging device signals indicative of a selected intensity, said halftone signal generator means including
• a spot function generator means for sampling said Z eliminator output signals at each pixel location and receiving said signal set from said intensity map generator means and generating therefrom signals indicative of a selected dot shape,
• a halftone position means for converting the current pixel position on a page to a position in a halftone space scaled therefrom, and
• a comparator means for comparing the intensity requested from the graphics accelerator means with the intensity of the current pixel received from the spot function generator means and generating signals enabling said current pixel should said requested intensity exceed a threshold value.

In a computer imaging system for use in generating signals indicative of an overall image having zero or more character elements of a plurality of pixels, the system further having a controller for receiving command signals indicative of parameters of the image and generating therefrom imposition signals for configuring the image in a selected sequence and orientation for presentation to an output imaging device;

• a rasterizer having a compressor means for generating character cache signals corresponding to said characters, a means for generating signals corresponding to a list of characters;
• a graphics accelerator for receiving signals from the rasterizer and generating therefrom signals for use by the output imaging device for imaging the image on a medium, the graphics accelerator means including a character decompressor means for use in decompressing signals corresponding to compressed characters received from said rasterizer, a Z eliminator means receiving signals from said character decompressor means corresponding to decompressed image signals including signals indicative of said characters, said Z eliminator means merging said received decompressed image signals and, if two of said decompressed image signals are designated for a given pixel;
• selecting which of said decompressed image signals are to be written for that pixel and suppressing non-selected signals for that pixel;
• an intensity map generator means for generating at least one signal set indicative of the intensity magnitude of each of the pixels, the system comprising:
• an interpreter means adapted to receive signals corresponding to the image, the interpreter means having an identifying means for generating signals identifying therefrom pixel signals corresponding to characters;
• and
• an intermediate interpreter buffer means for receiving signals from said interpreter means for corresponding to interpreted input file signals and providing said signals asynchronously to said rasterizer in response to received control signals.