Two-color printer

Abstract: A catalog of fonts, each font differing from the others in the bit patterns contained in its characters which when printed yield a different color, all fonts comprising the same number of identical characters, the characters being a predetermined number of shapes that can be assembled together to form an area. To the printer, the catalog appears to be a number of fonts, and can therefore be accessed by a printer that has a typical hardware system for printing text. However, when printed using a two-color printer, the printed output will be an area of any size filled in with the specified color.

Description: A printing system for printing using two colors, black plus a highlight color, and more specifically a printing system which has stored in memory several ink fonts, each of these fonts being a different shade of highlight color, the members of each font being a large number of shapes which can be assembled to form rectangles of any size from which the highlight areas can be assembled. To add highlight color to a typical black and white print, a xerographic printer can be designed with a tri-level development process. The photoconductor is charged in the form of an image where some areas are charged positively and some areas are charged negatively relative to non-image areas. Then, by using black toner with a positive potential and color toner with a negative potential, both black text and colored highlight areas can be printed on the same print in one pass. These highlight areas can be regular shapes such as a colored borders or highlighted areas of the page, or more complex shapes such as a rough approximations of flowers, or other figures. The highlight color is typically red, green or blue. Then, the printer, at any given moment, will have black toner and one toner of one of these three colors. It is left to the user to load any color, and to change to another color at any time by removing the original toner cartridge and inserting another. Toners are usually applied to paper to achieve variations of density by halftoning. In this embodiment, the halftone matrix will be assumed to be 8 by 8 pixels, each pixel being either white, black or colored. The resultant variations with red highlight and black toner can vary from white, light pink and light gray to red or black, and to any mixture of these. Most printers typically print characters, and therefore the hardware is optimized for the storage, accessing and printing of alphabetical or numerical character bit maps. Substituting a tri-level development process, it would be relatively simple to print text in black or in a highlight color. However, the requirement for producing arbitrary shapes in varying shades of color would complicate the hardware and software and impact run time. When the printer receives an instruction to print a specified color in a specified shape, it must define the area in the page bit map, produce a halftoned tile in the desired color, and then load the area with these tiles, all before printing can start. Clearly, this will impact unit cost and run time. What would be an improvement would be a printing system where arbitrary shapes and colors can be printed with equipment that was originally optimized to print text. GB-A-2 204 167 discloses a two-color printer arrangement in which a host computer is connected for sending data thereto. Page buffers are provided which have the capacity to store dot patterns of one page, a first buffer for one color and a second buffer for a second color. Information relating to the kind of color which can be printed is stored in code registers, one for each color. The printer has developing systems which correspond to the colors which are stored in code form in the code registers, the developing systems being changeable in accordance with the two colors which it is desired to print. If the developing systems are changed, the codes stored in the code registers are also changed. US-A-4 953 104 discloses a data storage system which uses multiple bit maps for the storage of data in device dependent form. Bytes from the memory block are used to define three separate overlapping pixel areas, one for each color, for example, cyan, magenta and yellow, which is to be printed. The characteristics of a font that vary within the font are the overall area and shape of the characters ("W" is larger than, and shaped differently from, "i") and the placement of the pixels within the area (the pixels of a "x" are placed differently from the pixels of an "o"). The color of the characters within the font normally do not change. They are assumed to be pure black or pure white. A typical printer is then set up to handle a large number of fonts (bold, italics, 10 point, 12 point, etc) which vary slightly from one another in at least one characteristic. In accordance with one aspect of the present invention, there is provided a two-color printer which uses two primary colorants to print on an output medium a highlight area of variable size in a predetermined color which is a combination of the color of the medium and of the two primary colorants, the printer including a memory containing a plurality of fonts each comprising a plurality of characters, characterised in that each font comprises a set of shapes having the same color which can be assembled to form an area of any rectangular size, each character comprising one of the shapes in the set, and in that each character comprises two equally sized and shaped bit maps, one bit map having its bits indicating the pixels to be printed in one colorant, and the other bit map having its bits indicating the pixels to be printed in the other colorant. This invention applies the same philosophy to colors and shapes, providing a printing system in which a variety of colors and shapes are created and stored in the system as though they were fonts. Each font is a set of shapes (squares and rectangles of various sizes) which all have the same color, and which can be used to assemble an area of any rectangular size. In this disclosed embodiment, there are 120 possible shapes, all of which are filled with a pixel pattern to produce the same color. Since the color is applied in bit patterns, there will be a patterns of pixels in an 8x8 pixel bit map or pattern to define the density of the color. However, since this is a two color system, with each color being independent of the other, there must be two pixel bit maps or patterns, one for black and one for the color. Each pixel bit map is one font character. There are 120 font characters for black and another 120 corresponding font characters for color. These font characters reside within a font file and can be loaded into a character dispatcher since they are now in a form that a text based imager can operate on directly. The same philosophy can be used for a full color printer. For example, four inks can be loaded into a four pass printer, typically cyan, magenta, yellow and black. Four fonts will then be required, one for each color, to produce the final print in any one color, and four hundred fonts will be needed to allow the user to choose between 100 colors. In an actual printing system there will be a large number of palettes in each "catalog", and several catalogs within the printer. The present invention will now be described by way of example with reference to the accompanying drawings, in which: Fig 1 is an ink catalog header; Fig 2 is a font list; Fig 3 is a list of primary entries; Fig 4 is a palette directory; Fig 5 is a palette header; Fig 6 is a screen set directory; Fig 7 is a pattern directory; Fig 8 is a color directory; Fig 9 is a texture directory; Fig 10 is a directory of screen definitions; Fig 11 is a screen definition; Fig 12 is is a pattern definition; Fig 13 is a color definition; Fig 14 is a texture definition; Fig 15 is a large fill character; Fig 16 is a 7X32 leading dots character; Fig 17 is a 3X2 leading dots character; Fig 18 is a 7X7 left corner character; Fig 19 is a 32X7 leading scans character; Fig 20 is a 7X32 trailing dots character; Fig 21 is a 7X7 right corner character; Fig 22 is a 32X32 mask; Fig 23 is a 32X32 mask per Interpress standard (a byte stream); Fig 24 is a 32X32 mask in DEC memory; Fig 25 shows the difference between a color which has uniform appearance and a texture which has visible structure; Fig 26 is a pictorial view of the relationship between screens, colors, patterns and textures; Fig 27 is a simple block diagram of the printing system; Figs 28 through 31 are data flow diagrams; Figs 28a, 28b and 28c are CD meta codes and CD codes (sorted by meta code); Fig 29A illustrates the method of filling a box; Fig 30A shows the ink character code groupings; Figs 31A and 32 show the color ink character code assignments; Fig 33 shows the number of character codes required for color inks; Fig 34 shows color ink size; Fig 35 is an example of filling a box using ink texture; Fig 36 is the texture ink fill character code assignments; Fig 37 is the number of character codes required for texture inks; Fig 38 is the texture ink size; Fig 39 is an example of a box fill TL/DL; Fig 40 shows a new entry being added to the new symbol table; Fig 41 shows the symbol table; Fig 42 shows the composition of Notype structure.D; Fig 43 shows the composition if ICATALOG structure.D; Fig 44 shows the composition of PRIMARY structure.D; Fig 45 shows the composition of PALLETTE structure.D; Fig 46 shows the composition of COLOR Sub-Option.D; Fig 47 shows the composition of Model Sub-Option structure.D; Fig 48 shows the composition of Scnset Sub-Option structure.D; Fig 49 shows the composition of Primary Sub-Pption structure.D; Fig 50 shows the composition of Values Sub-Option structure.D; Fig 51 shows the composition of Copts structure.D; Fig 52 shows the composition of Scanset structure.D; Fig 53 shows the composition of Scanset structure.D; Fig 54 shows the composition of Data Sub-Option structure.D; Fig 55 shows the composition of Size Sub-Option structure.D; Fig 56 shows the composition of Dtype Sub-Option structure.D; Fig 57 shows the composition of Plib Sub-Option structure.D; Fig 58 shows the composition of Pindex Sub-Option structure.D; Fig 59 shows the composition of SOPTS structure.D; Fig 60 shows the composition of TEXTURE structure. D; Fig 61 shows the composition of Pattern Sub-Option structure.D; Fig 62 shows the composition of In Sub-Option structure.D; Fig 63 shows the composition of PATTERN structure.D; Fig 64 shows the composition of POPTS structure.D; Fig 65 shows the composition of END structure.D. The preferred embodiment will now be described in detail. The present invention relates to a two-color printer which uses two colorants to print on an output medium a highlight area of variable size in a predetermined color which is a combination of the color of the medium and the two primary colorants. The printer comprises several fonts in a printer memory, each font comprising several characters, each character comprising two equally sized and shaped bit maps, one bit map having its bits indicating the pixels to be printed in one colorant and the other bit map having its bits indicating the pixels to be printed in the other colorant. The resultant pattern of pixels and the ratio of pixels per unit area in all of the characters are equal for all characters of a font. Each font has a set of characters which are equal in shape and size to those of every other font. Two colorants are provided for printing and a print job description is used to control the printer, specifying for each location on the printed output the font, the specific character of the font, and the colorants to be used in the printing process to print an area on the medium in the desired color. The bits of each bit map may either be spread evenly over the area of the bit map or may be grouped to create a visible texture. Some of the characters in the fonts may comprise shapes which are square or rectangular so that when the characters are placed in adjacent positions, a seamless rectangle of any desired shape and size can be constructed and printed. Fig 1 shows the arrangement of 13 words of data in the header of the catalog. The first three words in the header block contain the ink catalog name and file type in RAD50. The version of this ink catalog is the version number, for example, 1. The Ink Catalog Type is:1 - Monochrome, 2 - Highlight, and 3 - Full Color. For this embodiment, the type will be 2. The two time/unique words are a unique field within the header block. For example, this will contain the date and time of compilation. The following six words contain the block and word offsets which point to the start of the list of fonts, the list of primaries, and the start of the palette directory. The header portion of the ink catalog was designed to include key pieces of information. Such information includes three words which contain the name of the ink catalog plus the file type in Radix 50 format so that any referencing task could verify that this is indeed the correct ink catalog file that it needs. Next, a version word was added so that if the structure of an ink catalog changed, it could be easily checked by this version word. Next, an ink catalog type word was added to show which target machine this ink catalog was built for. Next, two words in the header contain unique words for each ink catalog. The time/unique words were added so that the task could specify the exact ink catalog it used during compilation to create a form. Input could then verify that the current ink catalog that resides on the disk is indeed the correct one. The next six words which are the block and word offsets pointing to the list of fonts, the list of primaries, and the palette directory were added so that the header may expand should there be a need to include additional information. The word offsets for the primary list and the palette directory are zero since these begin on a block boundary. All block and word offsets in this ink catalog structure are relative to the beginning of the ink catalog. Also, all reserved words will be zero. Immediately following the header is the list of fonts used in this ink catalog. Fig 2 is a font list. The number of fonts is the number the ink compiler has built within this ink catalog. The font block and word offsets are two words that point to an area within this ink catalog that has the user defined screens and inks in a font file format. The end of the font list is padded with zeros until a block boundary is reached. The font list follows immediately after the ink catalog header and is variable in length. First, the number of fonts is specified, followed by the block and word offsets that point to the area within this ink catalog that contains the user defined screens, colors, and textures for this ink catalog in a font file format. The font word offset is zero since the font data always begins on a block boundary. These fonts are accessed by the character reference word specified in a screen, color, or texture definition structure. If the list of fonts does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. Fig 3 is a list of primary colors. The primary list begins with the number of primary entries twenty words each. Sixteen words contain the primary name in ASCII, one word contains the primary ' s ID number, and three words contain the color coordinates. The three RGB value words are the color coordinates (RGB model) for this primary. Each is scaled by a factor of 10000 and expressed as an integer. The end of the primary list is padded with zeroes until a block boundary. The primary list begins on a block boundary for fewer disk accesses. The list of primaries starts with a word containing the number of primary entries. Each primary entry is a fixed length of twenty words. The first sixteen words contain a primary name which can be up to thirty-two ASCII characters. Should the primary name length utilize less then thirty-two characters, then the rest of the space will be filled with zeroes. Following the name will be the primary ' s ID number and the three color coordinates. The color coordinates are scaled by ten thousand and expressed here as integers. If the list of primaries does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. The list of primaries is not expected to be large. All entries in the primary list are in alphabetical order using the primary name. By having a fixed length entry and all entries in alphabetical order, a binary search may be done to find a particular primary quickly. Fig 4 is the palette directory. The first line is a list of all the palettes in the ink catalog. First is the number of palette entries. Then the palette entries follow. The palette entries are eighteen words long. Sixteen words contain the palette name in ASCII, and the following two words contain the block and word offsets to the palette definition. At the end of the first palette entry, other palette entries may follow. The end is padded with zeroes until a block boundary The palette directory begins on a block boundary. This is for fewer disk accesses. The palette directory starts with a word containing the number of palette entries. Each palette entry is a fixed length of eighteen words. The first sixteen words hold the palette name that could be up to thirty-two ASCII characters. Should the palette name length utilize less than thirty-two characters, then the rest of the space will be filled with zeroes. The block and word offsets point to the exact location for this palette definition. The word offset is zero since a palette definition always begins on a block boundary. If the palette directory does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. Using the palette name, all entries in the palette directory are in alphabetical order. By having a fixed length entry and all entries in alphabetical order, a binary search may be done to find a particular palette quickly. The following structures define a palette structure. There may be multiple palette structures within an ink catalog. There may exist a default palette which is created by the ink compiler. The contents of it are all the global screens and patterns that the user may have defined prior to the first palette command. The default palette is not to be confused with a user specified palette defined using the palette command. Fig 5 is the palette structure. The first six words are reserved in case there is a need for the palette header to hold additional information.The next eight words are the block and word offsets to the screen set (SCNSET), pattern, color, and texture directories. The end is padded with zeros until a block boundary. The palette structure header begins on a block boundary. This is for fewer disk accesses. It is a fixed length of fourteen words. Within the palette header, there are six reserved words in case there is a need for the palette header to hold additional information. The next two words are the block and word offsets which point to the beginning of the linked and sorted color definitions. The next eight words are the block and word offsets to the screen set, pattern, color, and texture directories. Because the directories always begin on a block boundary, the word offsets are zero. After a palette header there will be padding with zeroes until the next block boundary so that the SCNSET directory that follows will begin on a block boundary. Fig 6 is the SCNSET Directory. First is a list of all the SCNSETs within this palette. First is the number of SCNSET entries. Then the SCNSET entries follow. Each SCNSET entry is eighteen words which consists of the SCNSET name in ASCII and then two words that contain the block and word offsets to the SCNSET definition. All SCNSET entries are in alphabetical order. Other SCNSET entries may follow. The end is padded with zeros until a block boundary. The screen set (SCNSET) directory begins on a block boundary. This is for fewer disk accesses. Each entry is a fixed length of eighteen words. The first sixteen words hold the screen set name that can be up to thirty-two ASCII characters. Should the screen set name utilize less then thirty-two characters, then the rest of the space will be filled with zeroes. The block and word offsets point to the exact location of the screen set definition. If the screen set directory does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. Using the screen set name, all entries in the screen set directory are in alphabetical order. By having a fixed length entry and all entries in alphabetical order, a binary search may be done to find a particular screen set quickly. Fig 7 is the pattern directory. The number of pattern entries is a list of all the patterns within this palette. First is the number of pattern entries. Then the pattern entries follow. Each pattern entry is eighteen words which consists of the pattern name in ASCII and then two words that contain the block and word offsets to the pattern definition. All pattern entries are in alphabetical order. Other pattern entries may follow. The end is padded with zeroes until a block boundary. The pattern directory begins on a block boundary. This is for fewer disk accesses. Should the pattern name utilize less then thirty-two characters, then the rest of the space will be filled with zeroes. The block and word offsets point to the exact location of the pattern definition. If the pattern directory does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. Using the pattern name, all entries in the pattern directory are in alphabetical order. By having a fixed length entry and all entries in alphabetical order, a binary search may be done to find a particular pattern quickly. Fig 8 is the color directory. The number of color entries is a list of all the colors within this palette. First is the number of colors entries. Then the color entries follow. Each color entry is eighteen words which consists of the color name in ASCII and then two words that contain the block and word offsets to the color definition. All color entries are in alphabetical order. Other color entries may follow. The end is padded with zeroes until a block boundary. The color directory begins on a block boundary. This is for fewer disk accesses. Should the color name utilize less then thirty-two characters, then the rest of the space will be filled with zeroes. The block and word offsets point to the exact location of the color definition. If the color directory does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. Using the color name, all entries in the color directory are in alphabetical order. By having a fixed length entry and all entries in alphabetical order, a binary search may be done to find a particular color quickly. Fig 9 is a texture directory. The number of texture entries is a list of all the textures within this palette. First is the number of texture entries. Then the texture entries follow. Each texture entry is eighteen words which consists of the texture name in ASCII and then two words that contain the block and word offsets to the texture definition. All texture entries are in alphabetical order. Other texture entries may follow. The end is padded with zeroes until a block boundary. The texture directory begins on a block boundary. This is for fewer disk accesses. Should the texture name utilize less then thirty-two characters, then the rest of the space will be filled with zeroes. The block and word offsets point to the exact location of the texture definition. If the texture directory does not end exactly on a block boundary, there will be padding with zeroes until the next block boundary. Using the texture name, all entries in the texture directory are in alphabetical order. By having a fixed length entry and all entries in alphabetical order, a binary search may be done to find a particular texture quickly. Next are the SCNSET, pattern, color, and texture definitions. To allow for fewer disk accesses, all SCNSET definitions will begin on a block boundary. All pattern, color, and texture definitions less then 512 bytes will be stored in a block (none will span over two blocks). If there is insufficient amount of space available in a block to fit a pattern, color, or texture definition, then zeroes will pad to the block boundary and the definition will begin at the next block. All pattern, color, and texture definitions greater than 512 bytes will begin on a block boundary and may span multiple blocks. Fig 10 is the SCNSET definition. The number of SCREEN definitions is the number of SCREEN definitions that are in this SCNSET definition. The maximum distance is calculated using value b and value h of each screen. Value b is the percentage of black and value h is the percentage of highlight color for this screen. The block offset points to the screen definition. Other SCREEN directory entries may follow. Fig 11 is a SCREEN definition. There are two character reference words used to locate the black and the highlight bitmaps for this screen. Each character reference word holds the font index which is the index into the list of fonts at the beginning of the ink catalog. The character codes for the black bitmaps begin at 16, and the character codes for the highlight bitmaps begin at 136. The size N and size M values are the N columns by M rows for the bitmaps that follow. Although the bitmaps for this screen are defined in a font as specified by the character references, they are also defined here in the Screen definition. The length of the bitmap is given in words and is the same for all the following bitmaps. Other screen definitions may follow. This is the end of the SCNSET definition. Other SCNSET definitions may follow. A screen set (SCNSET) definition will always begin on a block boundary to allow for fewer disk accesses. It is not necessary for screen set definitions to be stored in any specific order since they can be searched using the SCNSET directory. The first word of a screen set definition contains the number of screen definitions that are included in this screen set definition. The next word contains the maximum distance calculated for the screens in this screen set. The maximum distance is the largest minimum distance where a minimum distance is calculated by taking a screen in the screen set and finding all the distances to every other screen in the screen set. After all the distances are calculated for a single screen, the smallest of these distances is considered a minimum distance. Distance is (value b1 - value b0 ) 2 + (value h1 - value h0 ) 2 . A screen set definition contains a screen directory which is made up of screen directory entries. There is a screen directory entry for every screen definition within the screen set. This directory will facilitate searching for a particular screen in a screen set. A screen directory entry is a fixed length of ten words. It begins with two words that are the percentages of black (value b ) and highlight color (value h ). Two reserved words were added for the full color implementation of the ink catalog so that a total of four values may be specified. Next, there are the block and word offsets which point to the actual screen definition. Thus, all the screens in a screen set have a screen directory entry that points to the actual screen definition. Screen directory entries are sorted by values beginning from lowest to highest value b ' s. Should there be identical value b ' s, then those entries will be from lowest to highest value h ' s. The screen directory entries are sorted to aid in searching for a particular screen definition. Searching will be done by values. If a certain screen does not exist within a screen set, the closest screen can be found using the maximum distance. A screen definition is variable length. It begins with two words that contain character reference b and character reference h . Character reference words are used to locate the black and the highlight bitmaps defined for this screen. Each character reference word represents the font index which is the index into the list of fonts at the beginning of the ink catalog. The character codes for the black bitmaps begin at 16, and the character codes for the highlight bitmaps begin at 136. A zero character reference indicates that there is no font for this screen. The two reserved words that follow will be used in the full color ink catalog for additional character references. Next, there are the size N and size M values which show the number of columns (bits) and rows (words), respectively, for the bitmaps that will follow. The range of size N is 1 to 2 10 and the range of size M is 1 to 2 10 . Next, there are two variable length bitmaps. The length of the bitmap specified is the length of a single bitmap and all the bitmaps that may follow are the same size. The number of bitmaps signifies the number of bitmaps that will follow. Bitmap b is for black and bitmap h is for highlight color. For future ink catalogs for full color, more bitmaps may follow bitmap h . Although the bitmaps are defined in a font as specified by the character references for use in line/meta mode, they are also defined here for use in Interpress mode. Fig 12 is the pattern definition. It was decided that fonts would not be built for patterns thus the use of a character reference word was unnecessary. In its place, there is provided a reserved word which is equal to zero. The size N and size M values are the N columns by M rows of the bitmap that follows. Although the pattern is defined in the above specified font, it is also defined here in the pattern definition. The length of the bitmap is given in words. This is the end of pattern definition. Other pattern definitions may follow. A pattern definition may begin on a block boundary to allow for fewer disk accesses. included in a pattern definition are a reserved word (0), size N , size M , and a bitmap. It is not necessary for pattern definitions to be stored in any specific order. They can be searched using the pattern directory. Fig 13 is the color definition. This embodiment can use only black plus one other color. Thus, we have indices for two colors. The low order byte contains index 1 and the high order contains index 2 . Index 1 contains the dominant primary color. Index 2 may be zero if there is only one color is used. There are two character reference words used to locate the black and the highlight bitmaps for this color. Each character reference word holds the font index which is the index into the list of fonts at the beginning of the ink catalog. The character codes for the black bitmaps begin at 16, and the character codes for the highlight bitmaps begin at 136. The block offset to screen points to the screen that is to be used to implement this color. This is the end of the color definition, other color definitions may follow. A color definition may begin on a block boundary to allow for fewer disk accesses. A color definition is a fixed length of eight words. It begins with the primary index word. The lower bytes contains index 1 and the higher order byte contains index 2 . Index 1 contains the dominant primary color used. Index 2 may be zero if there is only one primary color is used. A reserved word was added to hold two more primary indices for a multiple highlight color implementation. Then, there are two words that contain character reference b and character reference h that are copied from the screen definition used to implement this color. The character reference words are repeated here for speed of access in line mode. The character reference words are used to locate the black and the highlight bitmaps for this color. Each character reference word holds the font index which is the index into the list of fonts at the beginning of the ink catalog. The character codes for the black bitmaps begin at 16, and the character codes for the highlight bitmaps begin at 136. A zero character reference indicates that there is no font for this color. The two reserved words that follow will be used in the full color ink catalog for additional character references. The next two words contain the block and word offset to the screen that is used to implement this color. This will be used by the Interpress decomposer (IPD) to obtain the bitmaps for inks referenced by name. It is not necessary for color definitions to be stored in any specific order. They can be searched using the color directory. Fig 14 is the texture definition. This embodiment can use only black plus one other color. Thus, we have indices for two primaries. The low order byte contains index 1 and the high order byte contains index 2 . Index 1 contains the dominant primary color used in this texture. Index 2 may be zero if there is only one primary color used in this texture. There are two character reference words used to locate the black and the highlight bitmaps for this texture. Each character reference word holds the font index which is the index into the list of fonts at the beginning of the ink catalog. The character codes for the black bitmaps begin at 16, and the character codes for the highlight bitmaps begin at 136. The size N and size M values are the N columns by M rows of the bitmaps that follow. Although the bitmaps for this texture are defined in a font as specified by the character references, they are also defined here in the texture definition. The length of the bitmap is given in words and is the same for all the following bitmaps. This is the end of texture definition. Other texture definitions may follow. This is the end of palette structure. Other palette structures may follow. The end is padded with zeroes until a block boundary. This is the end of the ink catalog. A texture definition may begin on a block boundary to allow for fewer disk accesses. A texture definition is variable length. It begins with the primary index word. A reserved word was added to hold two more primary indices for a multiple highlight color implementation. Then, there are two words that contain character reference b and character reference h . Character reference words are used to locate the black and the highlight bitmaps for this texture. Each character reference word holds the font index which is the index into the list of fonts at the beginning of the ink catalog. The character codes for the black bitmaps begin at 16, and the character codes for the highlight bitmaps begin at 136. A zero character reference indicates that there is no font for this texture. The two reserved words that follow will be used in the full color ink catalog for additional character references. Next, there are the size N and size M values which show the number of columns (bits) and rows (words), respectively, for the bitmaps that will follow. The range of size N is 1 to 2 10 and the range of size M is 1 to 2 10 . Next, there are two variable length bitmaps. The length of the bitmap specified is for all bitmaps that follow. The number of bitmaps signifies the number of bitmaps that will follow. Bitmap b is for black and bitmap h is for highlight color. For future ink catalogs for full color, more bitmaps may follow bitmap h . Although the bitmaps are defined in a font as specified by the character references for use in line/meta mode, they are also defined here for use in Interpress mode. It is not necessary for texture definitions to be stored in any specific order. They can be searched using the texture directory. After the last palette structure is where the font file data resides. Each font that resides within the ink catalog begins on a block boundary. Fonts that do not end on a block boundary will be padded with zeroes until the next block boundary. The following discusses issues related to the creation and use of inks. A primary color is a dry ink toner that is applied through a stencil called a mask in order to image a color. The mask determines the portion of the page to be altered by the primary. Masks are implemented within an ink in two ways: as fill characters and as bit maps. Colors are inks with no visible structure and are implemented using a mask for each primary (one for black, one for highlight). Textures are inks with visible structure and are also implemented using a mask for each primary (one for black, one for highlight); the only difference between a color and a texture is in the makeup of the mask. Whereas a color is page-aligned and limited to an 8 bit X 8 bit ink, textures are object-aligned. The predominant primary color of an ink is the primary color which contributes the highest percentage to the specified color. This is always the first primary color in the list of primary colors provided by the ink catalog searching task. For inks, the FST entry for character code O ' 14 ' should initially contain a negative character alignment value and the HighlightColorStart or HighlightColorEnd CD-code depending on the predominant primary of the ink (HighlightColorStart if the predominant primary is any highlight color; HighlightColorEnd if the predominant primary is black). The FST entry for character code O ' 15 ' should initially contain a negative charactacter alignment value and the HighlightColorEnd CD-code. In addition, the FST entries for character codes O ' 12 ' and O ' 13 ' should initially contain a negative character alignment value and the HighlightColorStart and HighlightColorEnd CD-codes respectively for use by applications which fill rectangles using color. This scheme allows text (preceded in the DL by character code O ' 14 ' ) to be imaged in the predominant primary of the same ink used to fill rectangles (when the fill characters are preceded in the DL by character codes O ' 12 ' or O ' 13 ' to select the appropriate primary). These CD-codes will be updated at print-time, thereby enabling colorized resources to be printed on monochrome black-only printers. The following discusses an implementation for filling boxes with colors or textures using a combination of large fill characters, leading dots characters, trailing dots characters, leading scans characters, left corner characters and right corner characters. This section discusses the implementation of fill characters in an ink ' s font. Large Fill Character A 32 bit X 32 bit character (derived from an 8 bit X 8 bit ink) with CDF horizontal repeat used to expand its width to 1024 bits. The large fill character is illustrated in Figure 15. The right columns are replicated three times to give a width of 32 bits, and the bottom rows are replicated three times to give a height of 32 bits. The FST values are: AL = 020000 (CDF = 010 = horizontal repeat). FMA = @row 0. X = width = 128 bytes (1024 dots). Y = height = 32 scans. FSS = spacing = 1024 dots. In all cases where a primary does not contribute to a color, the corresponding black or color fill characters are represented in the ink font as space meta-codes with the appropriate FSS spacing, thereby saving font memory and disk space. Leading Dots Characters 7 characters [from 1..7 bits wide and 32 bits high, derived from an 8 bit X 8 bit ink] and representing the rightmost bits of the ink pattern, padded with zeroes to 16 bits such that their bitmaps will be addressable as left corner characters. The 7 bit X 32 bit leading dots character is illustrated in Figure 16. The FST values are: AL = 0. FMA = @row 0. X = width = 2 bytes (16 dots). Y = height = 32 scans. FSS = spacing = 7 dots The 3 bit X 32 bit leading dots character is illustrated in Figure 17. The FST values are:AL = 0. FMA = @row 0 X = width = 2 bytes (16 dots). Y = height = 32 scans. FSS = spacing = 3 dots. Left Corner Characters 49 characters [from 1..7 bits wide and from 1..7 bits high, derived from an 8 bit X 8 bit ink] and representing the lower-rightmost bits of the ink pattern, padded with zeroes to 16 bits such that they may share bitmap space with leading dots characters. The 7 bit X 7 bit left corner character is illustrated in Figure 18. The FST values are: AL = 0FMA = @row 1 of leading dots character (7 X 32)X = width = 2 bytes (16 dots)Y = height = 7 scans. FSS = spacing = 7 dots Leading Scans Characters 7 characters (32 bits wide and from 1..7 bits high, derived from an 8 bit X 8 bit ink) with CDF horizontal repeat used to expand their widths to 1024 bits and representing the lowermost bits of the ink pattern. These characters share bitmap space with the large fill character. The 32 bit X 7 bit leading scans character is illustrated in Figure 19. The FST values are: AL = 020000 (CDF = 010 = horizontal repeat). FMA = @row 25 of large fill character. X = width = 128 bytes (1024 dots). Y = height = 7 scans. FSS = spacing = 1024 dots. Trailing Dots Characters 7 characters [from 1..7 bits wide and 32 bits high, derived from an 8 bit X 8 bit ink] and representing the leftmost bits of the ink pattern, padded with zeroes to 16 bits such that their bitmaps will be addressable as right corner characters. The 7 bit X 32 bit trailing dots character is illustrated in Figure 20. The FST values are: AL = 0. FMA = @row 0. X = width = 2 bytes (16 dots). Y = height = 32 scans. FSS = spacing = 7 dots. Right Corner Characters 49 characters [from 1..7 bits wide and from 1..7 bits high, derived from an 8 bit X 8 bit ink] and representing the lower-leftmost bits of the ink pattern, padded with zeroes to 16 bits such that they may share bitmap space with trailing dots characters. The 7 bit X 7 bit right corner character is illustrated in Figure 21. The FST values are: AL = 0. FMA = @row 1 of trailing dots character (7 X 32). X = width = 2 bytes (16 dots). Y = height = 32 scans. FSS = spacing = 7 dots. Bitmaps are used to implement masks and therefore observe the Interpress conventions for bit- and byte-ordering. For instance, a 32-pixel X 32-pixel mask consists of 1024 pixels and can be visualized as illustrated in Figure 22. It would be implemented as a one-sample-per-pixel pixel array and would be packed as illustrated in Figure 23 (note that this illustrates memory as specified by the Interpress standard and does not reflect the DEC/Intel memory addressing scheme) These pixels would be transferred as a byte stream to the printing system ' s disk and eventually to memory as illustrated in Figure 24 (note that this illustrates memory according to the DEC/Intel memory addressing scheme): Ink Compiler The Ink Compiler is a non-print time, stand alone, utility that allows the user to define and create specific inks that can be used on the printer system. With this utility, the user can define palettes, colors, textures, patterns, and screens using commands similar to job source language (JSL). A standard ink catalog is provided in the system software. The following terms are defined as follows: Primary. This is a dry ink (toner). Ink. Imaging operators for the printer are described as applying a primary color to the page through a stencil called a "mask". The mask determines the portion of the page to be altered by the primary color. The ink and possibly the previous content of the altered portion of the page determine the appearance of the portion of the page. An ink can be transparent or opaque. Opaque inks alter the page by replacing the previous contents. Transparent inks allow the previous content of the page to show through the non-colored pixels of the ink. Color. This is an ink without gross structure. Colors are implemented using a halftone screen for each primary, black and color, which specifies the arrangement of the black and color pixels to be printed. This is also known as a "tint". Screen or Halftone Screen. This is used to implement a color. It specifies the arrangement of the black and color pixels to be printed. Texture. This is an ink with visible structure. A texture is the result of combining one or more color and pattern pairs. A pattern is a bitmap indicating the portion of the texture which is to have the color associated with that pattern. The pairs are processed in the order in which they are specified and the color is imaged as an opaque ink using the pattern as a mask. Pattern. This is a mask used to construct a texture. It can also be used to create a screen. Palette. A collection of screens, patterns, and inks. Ink Catalog. A collection of palettes. Fig 25 shows the difference between a color which has uniform appearance and a texture which has visible structure. Also, shown are multiple palettes where colors and textures are defined. Ink Source Language This section defines the structure and syntax of the Ink Source Language (ISL) which is used to create inks. Inks are organized into a multi-level hierarchy which is composed of catalogs, palettes, and palette items. The palette items are individual inks. Inks are grouped into collections called palettes. A group of users may employ several palettes for different applications. All the palettes used by the group are stored in an ink catalog. The use of separate catalogs for different groups of users permits each group to define and name inks independently. Creating Inks There are two types of inks: colors and textures. Inks typically contain two types of repeating structures. One type called micro-structure is non-visible or barely visible for colors, and the second type called macro-structure is easily visible for textures. The ink is defined by specifying a minimum portion of the structure which can be replicated to make the ink as large as the page. Because all colors are page-registered, a color is aligned with the page such that its origin and the origin of the page coincide. For textures, an optional offset allows the repeating structure of the ink to be aligned with the object being printed. An ink is defined by indicating the pixels to receive each of the primaries provided by the printing process. A monochrome printer has a single primary, typically black. A highlight color printer has at least two primaries, such as black and red. All colors that can be produced are created by combining one or more primaries on the printing medium. The printer assumes that the printing medium is white and no attempt is made to correct for non-white media. A color is specified by a device-independent description comprising selection of one of the supplied parametric color models and color parameters to be applied to that model. A color typically has a uniform appearance with no visible structure when viewed from a normal reading distance. A texture is a composite ink constructed from previously defined inks and patterns which indicate the portion of the texture to receive each ink. In contrast to colors, textures typically have a non-uniform appearance exhibiting some form of gross structure. Fig 26 is a pictorial view of the relationship between screens, colors, patterns and textures. The following sections describe the ink source language (ISL) in detail. Defining Primaries The primary statement is provided to associate a primary name with a dry ink (toner) identification number. This is used to identify that particular primary when communicating to or from the IOT. The format of the primary statement is as follows: ' primaryname ' : Primary ID = n, RGB = (rvalue, gvalue, bvalue); where n is from 0 to 255, and rvalue, gvalue, bvalue are expressed in decimal, scaled by 10,000, and given as an integer. Defining Ink Catalogs An ink catalog contains palettes which contain ink definitions that are designed for a specific user community. In many cases, a single catalog will be sufficient for an entire organization. Multiple ink catalogs may be established for specific groups within an organization that have different ink requirements. An ink catalog definition is initiated with the ICATALOG statement. The ink catalog comprises all palettes defined before the next ICATALOG statement, END statement, or physical end-of-file. All entities defined prior to and outside an ink catalog will be made globally available. Palette names must be unique within an ink catalog, but may be reused in different catalogs. The format of the ICATALOG statement is as follows: ' inkcatalogname ' : ICATALOG; Defining Pallettes Colors and textures are defined in collections called palettes. Multiple palettes may be required to support the needs of different user groups or to support the needs of different applications. The contents of a palette are defined by all the statements following the PALETTE statement. The palette comprises all colors and textures defined before the next ICATALOG statement, PALETTE statement, END statement, or physical end-of-file. Ink names must be unique within a palette, but may be reused in different palettes. The format of the PALETTE statement is as follows: ' palettename ' :PALETTE Defining Colors Color definition associates a color name with a specification for a desired appearance. This specification includes the color model, color parameter values, primaries, and screenset. Color models provide a method for specifying color in a manner that is easy to use and extensible. Four models are described below, providing a means of easily specifying colors for printers with capabilities ranging from monochrome to highlight and full color. Currently defined models are MONOCHROME, TINT, and HSM (Highlight Shade and Mixture). The user is advised to select the least capable model which provides the desired capabilities since this will minimize the amount of information that must be supplied. The interpretation of the color parameters values depends on the color model specified with the MODEL command. These values are used to associate with this color a screen within a screenset specified by the SCNSET command. Colors can access screensets that are global or residing within the current ink catalog and palette. Also dependent upon the color model are the primaries given by the PRIMARY command. Because the interpretation of the values and the primaries are dependent on the color model, the user should specify the model first unless the default model is desired. The general form of the COLOR statement is as follows: ' colorname ' : COLOR [colorcommands] [,VALUE[S] = {n|(n[,n]...)}]; Colorcommands are separated by a comma. colorcommands: = MODEL = { MONOCHROME |TINT|HSM|RGB|QUANTITY} {PRIMARY|PRIMARIES} = { ' primaryname ' |( ' primaryname ' [, ' primaryname ' ]...)} (The default primary name is the one with ID = 0. If however, no primary is given with ID = 0, then there will be no default primary. If this command is used with the COPTS statement, then the first primary name given will be used when creating a color with the MONOCHROME or TINT model and the first two will be used with the HSM or QUANTITY model) SCNSET = { ' screensetname ' | DEFAULT } The COPTS statement is optional, but is provided to facilitate definition of colors by allowing default values for commands of the COLOR statement to be specified. The default value for a command remains in effect until a new value is specified in a subsequent COPTS statement, the end of a palette, or the end of an ink catalog. Options specified on the COLOR statement override the default values provided by the COPTS statement. The format of the COPTS statement is as follows: COPTS colorcommands; Monochrome Model In the MONOCHROME model, objects are of a single primary, typically black. The general form of the COLOR statement in MONOCHROME model is as follows: ' colorname ' : COLOR MODEL = MON[,colorcommands]; Tint Model In the TINT model, the objects are described as a single primary or tints of that primary. For example, if the COLOR command specifies PRIMARIES = ' BLACK ' , then available colors are black and tints of black (grays). The VALUE command contains shade, where shade is in the range of 0 (white) to 100 (solid color, typically black). The general form of the COLOR statement in the TINT model is as follows: ' colorname ' : COLOUR MODEL = TINT, VALUE = shade[,colorcommands]; Highlight Shade and Mixture Model In the Highlight Shade and Mixture (HSM) model, the objects are described as a mixture of two primaries, the normal and highlight colors, applied to give the specified shade. The normal and highlight primaries are specified by the PRIMARIES option: PRIMARIES = (normal, highlight). The VALUE command contains shade and mixture. Shade is the quantity of the combination to apply from none (0) to the maximum amount (100). Mixture is the fraction of the combination which is the highlight color, expressed as a percentage. The general form of the COLOR command in the HSM model is as follows: ' colorname ' : COLOR MODEL = HSM, VALUE = (shade, mixture)[,colorcommands]; Quantity Color Model In the quantity model, the objects are described as a mixture of two primaries, the normal and highlight colors, applied to give the specified appearance. The normal and highlight primaries are specified by the PRIMARIES option:PRIMARIES = (normal, highlight). This is similar to the HSM model. The VALUE command contains two quantities which apply to the two primaries, normal and highlight. Both quantities range from none (0) to a maximum amount (100). The general form of the COLOR command in the QUANTITY model is as follows: ' colorname ' : COLOR MODEL = QUANTITY, VALUE = (normal quantity, highlight quantity)[,colorcommands]; Defining Screens A screenset is a collection of halftone screens with common characteristics. Screens are used to implement colors. They specify the arrangement of the black and color pixels to be printed. The screen set is referenced by the COLOR or COPTS statement. Multiple screen sets are allowed so that the user may select the proper screen characteristics for an application. For example, one screen set may use ha/Hone screens based on a blob growth algorithm. This screen set would be used for applications where a smooth variation in shading is required. Another screen set may use the highest possible screen frequencies. It would provide superior appearance for large tinted areas. Members of a screen set are specified by SCREEN commands following the SCNSET statement. The definition of a screen set must precede any reference to it. The format of the SCNSET statement is as follows: ' screensetname ' : SCNSET; Screens are halftone patterns used to implement colors. Within the SCREEN statement, there are three sets of screen commands: MODEL and VALUES; DTYPE, SIZE, and DATA; PLOC and PNAME. The MODEL AND VALUES commands are identical to those same commands in the COLOR statement. (Because the interpretation of the values and the data or patterns are dependent on the model, the user should specify the model first unless the default model is desired.) The DTYPE, SIZE, and DATA commands allow halftone patterns to be directly specified. The PLOC and PNAME commands allow ha/Hone patterns from an external location to be specified. The interpretation of the DATA and the PNAME commands depends on the color model specified with the MODEL command. When halftone patterns are directly specified, only the smallest repeating portion of the pattern need be specified. It will be replicated to the size required by the imaging subsystem. Data values are entered in the radix specified by the DTYPE command. Alternately, the value may be specified as a string constant, preceded by the radix indicator X for hex, O for octal, B for binary or D for decimal. It is recommended that all hex values begin with a digit so the compiler will not interpret any hex letters as radix indicators. The radix indicator takes precedence over the DTYPE command. Data values are grouped by parentheses, with either one group of values per primary, or the keyword NONE indicating that the corresponding primary is not used in constructing the color. The data is organized as an array of pixels, n columns by m rows as specified with the SIZE command. This corresponds to portrait orientation with column numbers increasing across the page and row numbers increasing down the page. Data values are placed into the array with the least significant bit corresponding to the highest column number. A 1-bit indicates that ink is to be deposited for the pixel. A 0-bit indicates that no ink is to be deposited for the pixel. If the value provides more than n pixels, the excess pixels are ignored. If less than n pixels are provided, the remaining pixels are filled with zeros. If less than m rows are given, then the ink compiler will repeat those rows given to make up the difference. However, if more than m rows are given, then an error message is generated and the screen will not be created. When halftone patterns from an external location specified by the PLOC command are used, individual patterns are referred to by name in the PNAME command. In the PLOC command if the keyword CURRENT is used, the pattern location is the current ink catalog and the current palette. (NOTE: All global patterns are considered part of the current ink catalog and palette.). In the PNAME command, either a pattern name or the keyword NONE must be specified for each primary. The keyword NONE indicates that the corresponding primary is not used to construct the color. Ink catalog and palette names given in the PNAME command will override those given in the PLOC command. When using the PLOC or PNAME commands, an error message will be generated if a specified ink catalog or palette location does not exist. Also, an error message will be generated if the pattern does not exist. When a halftone pattern is specified whether directly or from an external location using the TINT model with a value of zero, it will be taken as the definition of a highlight TINT screen. The format of the SCREEN statement is as follows: The SOPTS statement is provided to facilitate definition of screens. It allows default values for commands of the SCREEN command to be specified. The default value for a command remains in effect until a new value is specified for the command in a subsequent SOPTS statement, end of a palette, or end of an ink catalog. Commands specified on the SCREEN statement override the default values provided by the SOPTS statement. The format of the SOPTS statement is as follows: Defining Textures A texture is a composite ink. A texture is constructed by "imaging" a series of patterns each with a specific ink. The patterns are treated as masks and are "imaged" with the corresponding ink in the order specified. A texture is constructed by the following process. It is initialized to all zero pixels. For each pattern-ink pair, the result is calculated as follows: texture = (texture AND (NOT (pattern))) OR (pattern AND ink) The format of the TEXTURE statement is as follows: There must be an identical number of INKs and PATTERNs. For example ,if two (2) patterns are given then two (2) corresponding inks must also be given, the 1 st ink for the 1 st pattern, the 2 nd ink for the 2 nd pattern. Defining Pattern Ink Source Language Command Summary ' primaryname ' : PRIMARY ID = n, RGB = (rvalue, gvalue, bvalue); The PRIMARY statement is provided to associate a primary name with an identification number and the RGB color coordinates. The identification number, n,is used to identify that primary in communication to or from the IOT. Rvalue, gvalue, and bvalue are scaled by 10,000 and given as an integer. ' inkcatalogname ' : ICATALOG; An ink catalog definition is initiated with the ICATALOG statement. ' palettename ' : PALETTE;A palette definition is initiated with the PALETTE statement. COPTS colorcommands; The COPTS statement is optional. It is provided to allow default values for commands of the COLOR statement to be specified. ' colorname ' : COLOR [colorcommands][VALUE[S] = n|(n[,n]...)]; The COLOR statement associates a colorname with a specification for a desired appearance. colorcommands are as follows: A screen set is a collection of halftone screens with common characteristics. Members of a screen set are specified by SCREEN statement following the SCNSET statement. SCREEN screencommands; The SCREEN statement allows the user to define halftone patterns used to implement colors. screencommands are as follows: The SOPTS statement is provided to allow default values for commands of the SCREEN statement to be specified. soptscommands are as follows: A texture definition is initiated with the TEXTURE statement. texturecommands are as follows: The INK command is used along with the PATTERN command to construct a texture. The number of inks must match the number of patterns given. ' patternname ' : PATTERN patterncommands; A pattern definition is initiated with the PATTERN command. patterncommands are as follows: The POPTS statement is provided to allow default values for commands of the PATTERN statement to be specified. poptscommands are as follows: Ordering of ISL Statements Inks are organized into a multi-level hierarchy which is composed of ink catalogs, palettes, and palette items. When using ISL statments to define ink catalogs, palettes, or palette items, the ordering and grouping of statements are important since any item must be defined first before it can be referenced. Also, the ink compiler expects certain ordering of commands to allow the successful creation of ink catalogs. Ordering and grouping rules along with general rules are defined below. 1. Ordering and Grouping Gudelines: The first commands specified should be the PRIMARY commands. This command allows the customer to associate the desired name with a dry ink (toner) identification number. The ink compiler needs to know this information up front 2. A PALETTE command cannot precede the first ICATALOG command in an ISL file. This is because a palette must be defined within a specific ink catalog. 3. Any command which precedes an ink catalog command is considered global. Also, any command which is after an ink catalog command, but prior to the first palette command, is considered global to all the palettes within that ink catalog. The ink compiler will only allow commands to create screens and patterns to be global. 4. Stray commands, which are those commands that do not reside within a palette boundary or within the global area, are not allowed. General Rules 1. Ink catalog names must conform to the current printing system convention for file names, with all characters being alphanumeric and enclosed in single quotes. 2. Primary names must be enclosed in single quotes and have a limit of 32 alphanumeric characters. 3. Palette, screenset, pattern, color, and texture names must be enclosed in single quotes and have a limit of 32 alphanumeric characters plus the space character with at least one character being alphanumeric. 4. Keywords cannot be used as names. 5. Palette names must be unique within an ink catalog, but may be reused in different catalogs. 6. Screenset, pattern, color, and texture names must be unique within a palette, but may be reused in different palettes. 7. Primary ID numbers must be unique. 8. Comments are allowed and must be enclosed with /* and */. Any item must be defined before it can be referenced in another statement. One possible ordering of statements which will avoid this problem is shown below: An .ISL (ink source language) file is created using EDIT and contains the commands defined above in relation to Ink Source Language. The Ink Compiler will compile this file with the following command: ICO filename options where filename is explained below: filename..specifies the 1 to 6 alphanumeric character name of an ink source language (ISL) file which is the input to the ink compiler. This filename may optionally include the file extension.(.ISL.). where options may be any combination of the following and each are separated by a space: NOP[RINT] specifies that all source records and syntax or fatal errors are to be printed during compilation. If there are no syntax or fatal errors, there will be no print out. The default is to print all messages plus the source records. REP[LACE] specifies that the ink compiler may replace an existing ink catalog (.ICT) file with a new output file of the same name. This is the default. NOR[EPLACE] specifies that the ink compiler is not to create an ink catalog (.ICT) file if it has the same name as an existing file. REPLACE is the default. (NOTE: If both REPLACE and NOREPLACE are specified in the compilation command, then whichever was given last will be honored). TRA[Y] specifies that the listing and error messages from the ink compiler are to go to the sample tray. If TRAY is not specified, the printout will go to the output stacker. DIS[PLAY] specifies that all syntax error messages are to be displayed on the keyboard/display. The default is to print the syntax error messages only on the listing. Operator Message Summary The following new messages, which are shown here with a brief explanation, may be displayed to the operator by the ink compiler. Most of these messages are identical or similar to the PDL messages which are shown in the 4050 Reference Manual. All messages that exceed 80 characters will be truncated to 80 characters. Printed Error Message Summary The Ink Compiler is a two pass compiler and syntax analysis occurs during the first pass. If a syntax error is found, then an error message will be immediately generated for the line in which the error occurred and analysis will resume on the next Ink Source Language statement. The Ink Compiler tries its best to recover from errors found during the second pass. These error messages are generated for the entire ISL statement with this being after the terminating semicolon is processed. SYNTAX ERROR ON LINE 〈line number〉. (A syntax error was detected.) SYNTAX ERROR: The number of patterns and inks are not equal. (In a TEXTURE statement, the number of patterns is not the same as the number of inks.) SYNTAX ERROR: Expecting 〈value〉 and not 〈value〉. (During syntax analysis, the Ink Compiler was expecting a certain value and it was not found.) SYNTAX ERROR: Keywords cannot be used as names. (Keywords cannot be used as names.) SYNTAX ERROR: Cannot use name 〈name〉 as specified. (Invalid name given.) SYNTAX ERROR: Invalid keyword 〈keyword〉. (Invalid keyword was detected.) SYNTAX ERROR: Invalid command. (Invalid command was detected.) LINE 〈line number〉: Pattern location does not exist. (The external pattern location which is either an ink catalog or palette, specified with the PLOC/PNAME commands is not defined.) LINE 〈line number〉: Pattern does not exist. (The pattern specified with the PNAME command is not defined.) LINE 〈line number〉: Names should be unique. (Ink names must be unique within a palette, but may be reused in different catalogs.) LINE 〈line number〉: 〈name〉 has not been previously defined. (The ordering of ISL statements is important. All items must be defined before they can be referenced.) LINE 〈line number〉: Data values do not match size specified. (This message is given when the Ink Compiler cannot create a bitmap with the data values given.) LINE 〈line number〉: Command is inconsistent with model. (In the COLOR statement, the number of values and primaries depend on the color model specified. In the SCREEN statement, the number of values, datagroups, and patterngroups depend on the color model specified.) LINE 〈line number〉: Ink catalog must contain at least one palette. (An ink catalog must contain at least one palette.) LINE 〈line number〉: Encountered a premature END or EOF (END command or EOF (end of file) encountered unexpectedly.) LINE 〈line number〉: Value 〈value〉 is incompatible with radix. (Data value given could not be used with the DTYPE specified;) LINE 〈line number〉: Bad value 〈value〉 given. (In the VALUE command, shade or mixture was not in the range of 0 to 100; or in PRIMARY command, the ID was not in the range of 0 to 255.) LINE 〈line number〉: All primary names must be defined first. (Primary commands must be defined at the beginning of an ISL file.) LINE 〈line number〉: ICATALOG command must precede PALETTE command. (A palette command must reside in an ink catalog boundary.) LINE 〈line number〉: END command is not balanced. (Too many END commands were encountered.) LINE 〈line number〉: Primary ID numbers must be unique. (The Ink Compiler will not accept similar primary ID ' s.) LINE 〈line number〉: 〈name〉 cannot be created. (Due to errors, a screen, color, texture, or pattern could not be created.) LINE 〈Line number〉: Ink does not exist. (There is no such ink defined.) LINE 〈line number〉: Size command is invalid. (The size command takes two values: n and m. n or m can only be 2, 4, or 8.) LINE 〈line number〉: Command exceeds Ink Compiler ' s capability. (The TEXTURE command and the RGB color model exceed the Ink Compiler ' s capability. Also, any command other than SCNSET, SCREEN or PATTERN in the global area exceeds the Ink Compiler ' s capability. Stray commands (those commands which do not reside within a palette boundary or within the global area) exceed the Ink Compiler ' s capability.) LINE 〈line number〉: Maximum limit has been exceeded. (The maximum number of palettes (999), ink fonts (65534), or primaries (256) has been exceeded.) LINE 〈line number〉: WARNING! Screen approximation occurred. (The specified screen does not exist in the screenset, so the closest screen was used instead. The following is the system default ink catalog. The first four entries are examples of primaries (toners). 'BLACK': PRIMARY ID = 0, YES = (0,0,0); 'GREEN': PRIMARY ID = 27, YES = (1226,-852,6); 'BLUE': PRIMARY ID = 28, YES = (0,0,0); 'RED': PRIMARY ID = 29, YES = (2285, 3203, 1657); The ID number identifies the commercial number of the ink, and the YES value is the industry standard definition of the color. The following is a portion of a typical catalog of colors. 'BACKGROUNDS': SCNSET; /* 2X4 CELL WITH OFFSET, 45 SCREENS */ SOPTS MODEL = HSM, SIZE = (4,4), DTYPE = HEX; SCREEN VALUES = (0,0), DATA = (NONE,NONE); SCREEN VALUES = (10,0), DATA = ((8,0,2,0),NONE); SCREEN VALUES = (20,0), DATA = ((0C,0,3,0),NONE); SCREEN VALUES = (38,0), DATA = ((0C,4,3,1),NONE); SCREEN VALUES = (52,0), DATA = ((0C,0C,3,3),NONE); SCREEN VALUES = (65,0), DATA = ((0C,0E,3,0B),NONE); SCREEN VALUES = (80,0), DATA = ((0C,0F,3,0F),NONE); SCREEN VALUES = (95,0), DATA = ((0D,0F,7,0F),NONE); SCREEN VALUES = (100,0), DATA = ((FF,FF,FF,FF),NONE); SCREEN VALUES = (20,50), DATA = ((8,0,2,0),(2,0,8,0)); /* 10,10 */ SCREEN VALUES = (30,66), DATA = ((8,0,2,0),(3,0,0C,0)); /* 10,20 */ SCREEN VALUES = (48,79), DATA = ((8,0,2,0),(3,1,0C,4)); /* 10,38 */ SCREEN VALUES = (62,84), DATA = ((8,0,2,0),(3,3,0C,0C)); /* 10,52 */ SCREEN VALUES = (75,87), DATA = ((8,0,2,0),(3,0B,0C,0E)); /* 10,65 */ SCREEN VALUES = (90,89), DATA = ((8,0,2,0),(3,0F,0C,0F)); /* 10,80 */ SCREEN VALUES = (100,94), DATA = ((8,0,2,0),(7,0F,0D,0F)); /* 6,94 */ The screen value is the amount of each color 1/2 the time. Thus, SCREEN VALUES = (20,50) means that the first primary is applied at a 20% level for the first half of the screen (= 10%) and the second primary is applied at a 50% level for the second half of the screen (25%). The DATA represents the bit map in hex. Thus for a 4 by 4 bit matrix, if DATA = 8,0,2 0, then the first line of the bit map is 1000, the second is 0000, the third is 0010, and the fourth is 0000. In the program the primary colors are identified as follows: 'RED': COLOR PRIMARY = 'RED'; 'BLUE': COLOR PRIMARY = 'BLUE'; 'GREEN': COLOR PRIMARY = 'GREEN'; 'BLACK': COLOR PRIMARY = 'BLACK'; The following are examples of colors that can be created from red and black primaries: 'WHITE': COLOR VALUES = (0,0); 'LIGHT GRAY 3': COLOR VALUES = (28,0); 'DARK GRAY 2': COLOR VALUES = (59,0); 'BLACK': COLOR VALUES = (100,0); 'LIGHT PINK 1': COLOR VALUES = (25,100); 'MODERATE PINK 3': COLOR VALUES = (44,100); 'DARK PINK 3': COLOR VALUES = (53,100); 'MODERATE RED 2': COLOR VALUES = (59,100); 'DEEP RED 5': COLOR VALUES = (78,100); 'RED': COLOR VALUES = (100,100); 'PINKISH GRAY 2': COLOR VALUES = (20,40) 'GRAYISH RED 8': COLOR VALUES = (56,45); 'DARK RED 7': COLOR VALUES = (75,41); 'REDDISH GRAY 3': COLOR VALUES = (46,17); 'BLACKISH RED 4': COLOR VALUES = (83,10); The compiler will produce these files by the process shown as data flow diagrams on Figs 27 through 31. Fig 27 is a simplified diagram of the entire compiler. The OCS is the operating system that the operator works with. User commands entered at the terminal are sent to the compiler and the compiler generates formatted messages to be displayed at the terminal. The compiler works as an interpreter in that commands in the form of instructions and data are operated on by the compiler one at a time as they are entered. Any errors encountered in the input commands result in an error message which is sent from the message file to the operator. The ISL file stores and transmits source records to the compiler which are used in conjunction with the commands to build an ink catalog. The ICOPRT.TMP file keeps a record of the process by storing source records and error messages. Fig 28 shows the process in more detail. The OCS is the operating system at which the operator types in user commands. At 1.0 these commands are verified and if any errors are encountered, the process is aborted and a code number corresponding to the associated error message is sent to the display message section 4.0 where the code number is translated into a text message and sent to the operating system for display. This message can also be sent to the Print Listing if the user needs a printed version. Commands are sent to the user option file, and the source record and error messages are stored in the ICOPRT.TMP file. The user options are taken in by the parse Commands section 2.0 and are parsed into tokens. Then each token is acted upon in order. If the command is to access a previously entered file, it is taken from the ISL file, and if it is to access a previously entered command it is taken from the command properties file. Commands are entered into the command structure and data is entered into the New Entry file. The new data is then acted upon in accordance with the new command by the execute command section 3.0 which results in a new symbol table and a new ink catalog. Fig 29 shows the parse command section 2.0 of Fig 28 in more detail. The contents of the ISL file is read into the read user file section 2.4 a block at a time, and is parsed into tokens which are sent, one at a time, to the lexical analyzer 2.1 and the analyze syntax section 2.2 for error checking. If this is the first pass, the process ends here. If this is the second pass, the program continues by storing new data in the new entry file and new commands in the command properties file. The build command structure section 2.3 then uses the command properties to build a command structure. The build command structure 2.3 section of Fig 29 is shown in more detail in Fig 30. The command properties are distributed by type as shown, resulting in separate files for the building of catalogs, lists of primaries, palettes, etc, all of which are stored in the command structure file. Fig 31 shows that either the new entries are acted on by the commands in the command structure in the build options List section 3.1 to generate a symbol table, or that the symbol table entries are acted upon in the build ink catalog section 3.2 by the commands to create an ink catalog. Each element in the discussion of the data flow diagrams 27 through 31 is described in more detail as follows. The large fill character is used to provide most of the fill for any rectangular area. It is 32 bits wide by 32 bits high (extended to 1024 bits wide via the CDF horizontal repeat function in order to reduce the number of DL characters required to fill a rectangle). The Dimension meta-code is used to truncate the width of the fill to within 7 dots of the desired fill boundary. No similar technique exists to enlarge the pattern in the scan direction. Therefore, a new DL is required for each 32 scans. The Dimension meta-code is used to truncate the height of the fill to the desired scan line boundary. Large fill is positioned with a fixed relationship to the page, e.g. as a page-registered ink. As a result, additional characters are required to complete the fill. Leading dots characters fill the dots before large fill on the scan line. Trailing dots characters fill the dots following the large fill on the scan line. Leading scans characters fill the scan lines before the large fill. There are no trailing scan characters since the large fill character can be truncated in the scan direction using a Dimension meta-code. Left corner characters are used to fill the upper-left corner. Right corner characters are used to fill the upper right corner. Fill for the lower left corner is formed by truncating a leading dots character using the Dimension meta-code. Fill for the lower right corner is formed by truncating a trailing dots character using the Dimension meta-code. Leading dot characters provide fill between the left fill boundary and the page-registered positioning of large fill. A character is required for each width from 1 to inkSizeX-1 dots (e.g., from 1 to 7 dots given an 8 X 8 ink size). The characters contain the rightmost bits of the ink pattern. All leading dots characters are 32 bits high to match the height of large fill character. Bitmaps are padded to 16 bits in width to permit portions of the bitmap to be used as (upper) left corner characters. When dimensioned for use as lower left corner fill characters, their x-dimension must be specified as 2 bytes (16 bits). CD Meta Codes and CD Codes (Sorted by Meta Code) Meta Code (from DL) CD Code (mapped from FST) Meaning Followed by: Notes This # of bytes These bytes mean: Many different codes (usually all otherwise unused meta codes below 40 and also unused character values within font. 4 Space 0 Spacing value is taken from FSS word in FST. No specific value 14 Graphic Space X 0 Not used in any Xerox font. No specific value 15 Graphic Space Y 0 Not used in any Xerox font. 0 7 Font Switch (FS) 1 Font index 1 2 End of Line (EOL) 0 2 1 Landscape (LS) 0 3 3 Overlay 0 4 5 Abs Dot 2 Next dot address 5 6 Rel Dot (RD) 2 Offset to next dot address 6 10 Absolute Scan 2 Next scan line 7 11 Relative Scan 2 Offset to next scan line 10 12 Dimension (DIM) 2 Replaces FS dimension value 11 13 Portrait 0 12 20 Highlight Color Start (HCS) 0 Used only in inks in conjunction with fill characters 13 21 Highlight Color End (HCE) 0 Used only in inks in conjunction with fill characters 14 20 Highlight Color Start (HCS) 0 15 21 Highlight Color End (HCE) 0 16 16 Extended Dimension 4 Replaces FS dimension value 17 17 Escape n Prefix for extended codes all values are octal Trailing dots characters provide fill between the Dimension meta-code truncation of large fill and the right fill boundary. A character is required for each width from 1 to inkSizeX - 1 dots (e.g., from 1 to 7 dots given an 8 X 8 ink size). The characters contain the leftmost bits of the ink pattern. All trailing dots characters are 32 bits high to match the height of large fill character. Bitmaps are padded to 16 bits in width to permit portions of the bitmap to be used as (upper) right corner characters. When dimensioned for use as lower right corner fill characters, their x-dimension must be specified as 2 bytes (16 bits). Leading scans characters provide fill between the top fill boundary and the page-registered positioning of large fill. Separate bitmaps for these characters are not necessary; their FST entries point into the bitmaps for the large fill character. A character is required for each height from 1 to inkSizeY-1 scans (e.g., from 1 to 7 scans given an 8 X 8 ink size). The characters contain the last scans of the ink pattern. All leading scans characters are 32 bits wide (extended to 1024 bits wide via the CDF horizontal repeat function, to match the width of the large fill character). The Dimension meta-code is used to truncate the width of the fill to within 7 dots of the desired fill boundary. Left corner characters provide fill between the origin of the fill (upper left corner) and the page-registered origin of large fill. Separate bitmaps for these characters are not necessary; their FST entries point into the bitmaps for leading dots characters. Character codes are required for heights from 1 to inkSizeY-1 scans for each leading dot character (e.g., from 1 to 7 scans given an 8 X 8 ink size). The total number of character codes required is (inkSizeX-1)*(inkSizeY-1) = 7*7 = 49. Right corner characters provide fill between the Dimension meta-code truncation of leading scan fill and the right fill boundary (upper right corner). Separate bitmaps for these characters are not necessary; the FST entries for these characters can point into the bitmaps for trailing dots characters. Character codes are required for heights from 1 to inkSizeY-1 scans for each trailing dot character (e.g., from 1 to 7 scans given an 8 X 8 ink size). The total number of character codes required is (inkSizeX-1)*(inkSizeY-1) = 7*7 = 49. An ink implements the fill characters for the two primaries that comprise every ink. Figs 30, 31 and 32 show the character code assignments for the black and color fill characters. Black fill characters should be preceded in the DL by the HighlightColorEnd meta-code using character code O ' 13 ' from the ink; color fill characters should be preceded in the DL by the HighlightColorStart meta-code using character code O ' 12 ' from the ink. Figs 33 and 34 show some sizing information for color inks. Texture fill is accomplished using a single large fill character which is repeated and trimmed to size using the Dimension meta-code. By registering the texture to the rectangle being filled, the area can be filled to within 7 dots of the right edge of the rectangle. Trailing dots fill characters are used to fill the remaining space. This is illustrated in Figure 35. The large fill character is repeated, as necessary, in the DLs to provide most of the fill for the rectangular area. If the area is not covered exactly using large fill, one additional large fill character is added to the DL and trimmed using the Dimension meta-code. Since trimming is only to a byte boundary in the scan direction, additional dots are filled using trailing dots characters. The large fill character contains the complete texture pattern. Trailing dots characters provide fill between the Dimension meta-code truncation of large fill and the right fill boundary. A character is required for widths from 1 to 7 bits for each byte of width of the texture. The height of the characters is the same as that of the large fill character. The following are fill algorithms.

Claims: A two-color printer which uses two primary colorants to print on an output medium a highlight area of variable size in a predetermined color which is a combination of the color of the medium and of the two primary colorants, the printer including a memory containing a plurality of fonts each comprising a plurality of characters, characterised in that each font comprises a set of shapes having the same color which can be assembled to form an area of any rectangular size, each character comprising one of the shapes in the set, and in that each character comprises two equally sized and shaped bit maps, one bit map having its bits indicating the pixels to be printed in one colorant, and the other bit map having its bits indicating the pixels to be printed in the other colorant. A printer according to claim 1, wherein each font has a set of characters which are equal in shape and size to the set of characters of every other font. A printer as claimed in claim 1 or 2, wherein one of the colorants is black. A printer as claimed in any preceding claim, wherein the printer is a tri-level single-pass xerographic printer. A printer as claimed in any preceding claim, wherein the bits in each bit map may either be spread evenly over the area of the bit map, or be grouped to create a visible texture. A printer as claimed in any preceding claim, wherein some of the characters in the fonts comprise shapes which are square or rectangular, so that when the characters are placed in adjacent positions, a seamless rectangle of any desired shape and size can be constructed and printed.

Inventors: GAINES MARK, LAMAN ROBERT R, GAINES, MARK, LAMAN, ROBERT R.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1992
Main classification: B41J2
IPC codes: B41J2, G06K15, G03G15, H04N1