Character-based monochromatic representation of color images

Abstract

Forming a character-based monochromatic image from a digital representation of a color image by (1) forming a character-based representation of the color image in which a plurality of color characters each describe the background and foreground color within a defined area of the color image, (2) providing a plurality of color pattern masks each corresponding to a color in the color image and comprised of a pattern of light and dark dots capable of providing, in the monochromatic image, visual discrimination between areas of different color, (3) transforming the color characters to monochromatic characters by replacing the background and foreground color of each color character with the corresponding pattern of light and dark dots, and (4) displaying the monochromatic characters on a character-based output device (e.g., a CRT display driven by a character-based controller).

Description

1. Field of the Invention

The present invention relates to the processing and representation of color images and, more particularly, to a method and apparatus for the representation of color images in data processing systems having monochromatic output devices, such as printers and CRT displays. In this context, an image may be defined as a visual representation of information wherein the information may be pictorial or textual or both and may be comprised of alphanumeric characters or symbols or graphic characters, symbols or elements or a combination thereof. A color image may be further defined as an image wherein the elements or areas comprising the image, whether alphanumeric or graphic, are defined by various colors.

2. Prior Art

Many presently available data processing systems, ranging from public data base television type systems (such as the TELETEL and PRESTEL videotex systems), to `home` computers, to very expensive and complex computer-aided-design (CAD) systems, are capable of manipulating and representing monochromatic and color images. Many systems, however, are wholly or partially limited to monochromatic imagery, either for cost considerations or because image generation and display is a secondary or later added capability of the system. For example, a system may originally have been designed only for monochromatic operations or, while the system itself is capable of operating with color images, the display or hard copy devices connected for the system, such as the CRT and printers, may have only monochromatic capabilities. A recurring problem with systems having image capabilities is presented whenever color images, for example, generated or provided by a system having color image capabilities, are to be visually represented by a system having, for example, only a monochromatic CRT or monochromatic printers. The problem arises when the owner of a personal computer with a conventional 80 column by 24 line monochromatic CRT display desires to communicate with a videotex service (e.g., TELETEL and PRESTEL) that transmits information intended to be viewed on a 40 column by 24 row color display. In general, visual outputs of color images by monochromatic means have proven unsatisfactory, the images being esthetically unpleasing or in many cases visually distorted or transformed to an unacceptable extent.

One basis of the problem is that monochromatic and color processes differ in the information presented to a viewer in order for the viewer to distinguish between areas of an image. That is, color processes distinguish between various areas of an image by both color and shade of color, that is, the lightness or darkness of a color. For example, three areas may be distinguished in that one is red, one is light blue and one is dark blue; the red area is distinguished from the blue areas by color and the blue areas are distinguished by being of differing shades of blue. In monochromatic processes, however, the various areas of an image are distinguished only by shade, generally referred to as `half tones`, ranging from `black` to `white`.

A transformation of a color image to a monochromatic image thereby requires that color and shade information contained in a color image be transformed into shade information in a monochromatic image. This results, in present systems, in a loss or distortion of visual information. For example, in the simplest systems the `dark` combinations of color and shade information from a color image are transformed into a `black` monochromatic shade while the `light` combinations are transformed into a `white` monochromatic shade. The result can be a total distortion of the original color image and at least a loss of visual information and a degradation of visual esthetics.

In more complex systems, the various combinations of color and shade appearing in the color image original are transformed into their nearest equivalent `gray scale` monochromatic shade. The most common example of such a system is in `black and white` photography of a colored object, such as a landscape; that is, the various colors and shades appearing in the scene are replaced, in the photograph, by their shade of gray equivalents. While such a system provides less distortion than the simple system described above, there may still be some distortion of the original visual information and often a loss of esthetics. This distortion occurs because many combinations of color and shade have the same `gray scale` equivalent; for example, a red area, a blue area and a green area, easily distinguishable in color, may have the same gray equivalent and appear as the same shade of gray in the monochromatic image.

It is thereby an object of the present invention to provide an improved method and apparatus for representing color images through monochromatic means.

SUMMARY OF THE INVENTION

In general the invention features forming a character-based monochromatic image from a digital representation of a color image by (1) forming a character-based representation of the color image in which a plurality of color characters each describe the background and foreground color within a defined area of the color image, (2) providing a plurality of color pattern masks each corresponding to a color in the color image and comprised of a pattern of light and dark dots capable of providing, in the monochromatic image, visual discrimination between areas of different color, (3) transforming the color characters to monochromatic characters by replacing the background and foreground colors of each color character with the corresponding pattern of light and dark dots, and (4) displaying the monochromatic characters on a character-based output device (e.g., a CRT display driven by a character-based controller).

In preferred embodiments, each monochromatic character comprises a matrix of pixels and each matrix of pixels is represented in a memory as a corresponding matrix of bits; a color-pattern matrix of bits is provided to represent each color pattern mask, with a bit in one state representing a light dot or a portion thereof and a bit in the other state a dark dot or a portion thereof; there is generated for each color character a foreground-background matrix of bits in which a bit in one state represents the presence of foreground color and a bit in the other state the presence of background color, the foreground-background matrix is combined with the color-pattern matrix of the foreground color in such a manner as to replace the bits in the foreground-background matrix with the bits in the color-pattern matrix in areas of foreground color, and the foreground-background matrix is combined with the color-pattern matrix of the background color in such a manner as to replace the bits in the foreground-background matrix with the bits in the color-pattern matrix in areas of background color; color characters are fewer in number than monochromatic characters and the defined area represented by each color character is larger than the area of the monochromatic image represented by the monochromatic character; the color characters include alphanumeric characters having the foreground color in the body of the character and the background color elsewhere and the transforming step includes the steps of generating for each color character at least two monochromatic characters one of which is a space character (all background), so that the body of the character appears in fewer than all of the monochromatic characters corresponding to the color character; there are two monochromatic characters for each color character and one of the two monochromatic characters is made a space character (all background) and the other contains the body of the alphanumeric character; there are two monochromatic characters for each color character and the color characters include graphical characters of a type having two vertical rows of blocks each of which can be foreground or background color and wherein a first monochromatic character containing one vertical row of blocks is formed and a second monochromatic character containing the other vertical row of blocks is also formed; the color image comprises a videotext image; the character-based output device is capable of displaying no more than a maximum number of monochromatic characters at any one time and wherein a newly generated monochromatic character is compared to a library of earlier generated monochromatic characters already part of the monochromatic image and is added to the library only if the newly generated character is not already present there; the library is a dedicated character memory in circuitry controlling said output device; redundancies (e.g., presence of spaces in portions of enlarged alphanumeric characters) in the monochromatic characters are detected and only one character is added to the library instead of one for each redundant character; fewer color pattern masks are provided than there are colors in the color image and each color for which no pattern mask is provided is represented as the inverse of one of the patterns by instructing the output device to display a character containing that color in a reverse video manner; color characters containing both a color for which there is a color pattern and colors for which an inverse of a pattern is required are transformed into monochromatic characters by doing the inversion of color pattern during the process of substituting the color patterns for the foreground and background areas of a character.

In another aspect of the invention, the color pattern masks used are those given in the tables in the text of the specification.

Other features and advantages of the invention will be apparent from the following description of preferred embodiments and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a computer system incorporating the present invention;

FIGS. 2A and 2B are a block diagram of the computer system of FIG. 1;

FIG. 3 is a diagrammic representation of the software structure of the computer system of FIGS. 1, 2A and 2B;

FIGS. 4A and 4B are a representation of 8 by 8 color pattern masks for the colors black, red, green, yellow, blue, magenta, cyan and white;

FIGS. 5A, 5B and 5C are a representation of 20 by 16 color pattern masks for the colors black, red, green, yellow, blue, magenta, cyan and white;

FIG. 6 is a diagrammatic illustration of the color to monochromatic image transformation method of the present invention.

FIG. 7 is a diagrammatic illustration of the character enhancement method of the present invention; and

FIGS. 8A, 8B and 8C are illustrative representations of a color image transformed into a monochromatic image with, respectively, 8 by 8 arrays, 20 by 16 arrays and with enhancement of alphanumeric characters.

FIGS. 9A, 9B and 9C are illustrations of typical videotext graphical and alphanumeric characters.

FIGS. 10 and 11 show the enlargement that the graphical and alphanumeric videotext characters undergo for display on an 80-column CRT.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following description will first briefly present the general structure and operation of the hardware and software of a computer system incorporating the present invention and capable of performing image processing and display operations and of communications operations, including communications of images. The structure and operation of such a system will be well understood, as presented herein, by one of ordinary skill in the art and further details of the structure and operation of such a system are presented in U.S. patent application Ser. No. 440,668, filed Nov. 10, 1982 and incorporated herein by reference. The specific system selected for illustrative purposes is a Wang "Professional Computer" available from Wang Laboratories, Inc., Lowell, MA 01851. Having presented a context, that is, apparatus in which to practice the invention, the color to monochromatic image transformation method of the present invention will then be described in detail.

The following will then describe an exemplary color image system which may be used as source of color images to be transformed by the above described data processing system. The color images and system described therein are representative of many other commonly used color image systems which may be sources of color images to a system as described above. Other sources of color images, such as color graphic computer systems, may also serve as sources of color images, as may the exemplary system described in the present patent application. In the latter case, the color transformation of the present system may be used, for example, to transform a color image generated by a system when a monochromatic printer connected from the source system is used to provide a hard copy of images created therein.

The color transformation of the present invention may be used in relation to videotex systems such as TELETEL and PRESTEL. PRESTEL is a public data base television type system used in the United Kingdom; PRESTEL is a trademark of the British Post Office for PRESTEL services. PRESTEL is presently used, for example, to selectively distribute, under viewer control, information of interest to the public from a central PRESTEL data base. The information contained in this data base may pertain, for example, to weather and stock market reports and shopping guides and entertainment guides. The information so provided is primarily in the form of color images containing both text, that is, alphanumeric characters and symbols, and graphic or pictorial elements.

1. COMPUTER SYSTEM STRUCTURE AND OPERATION

Referring to FIG. 1, an isometric view of the computer system is shown. System 10 includes a Display 12, a Keyboard 14 and a Central Processing Unit (CPU) 16. Display 12 and Keyboard 14 are the primary means by which information, for example, text, is communicated between the system and a user. CPU 16, which is connected to Display 12 and Keyboard 14 by cables which are not shown, includes a memory for storing programs and data and a general purpose arithmetic and logic unit (ALU). CPU 16 may further include disc drives for storing programs and data and interfaces to peripheral devices, such as printers, disc drives and telecommunications devices. As described above, System 10 may be comprised, for example, of a "Professional Computer" available from Wang Laboratories, Inc., Lowell, MA 01851.

A. Hardware Structure and Operation

a. ALU and Busses

Referring to FIGS. 2A and 2B, a block diagram of System 10 is shown. System 10's ALU in CPU 16 is comprised of a Main Processor (Main P) 18 and a Co-Processor (CO-P) 20. Main P 18 and CO-P 20, may, for example, respectively be a 16 bit Intel 8086 ALU and an Intel 8087 numerics processor extension. Main P 18 and CO-P 20 perform all arithmetic and logic operations for CPU 16, including addressing, memory references, and control of Input/Output (I/O) operations.

Main P 18 and CO-P 20 communicate through Local Bus 22 and with the remainder of CPU 16, Display 12, Keyboard 14 and all peripheral devices through Address Bus 24, Data Bus 26 and Control Bus 28. The interface between Main P 18 and CO-P 20 and Busses 24, 26 and 28 is through Address Latch 30, Data Transceiver 32 and Bus Control 34.

b. Internal Control Logic

Referring next to CPU 16's internal control logic, associated with Main P

Claims

1. A fluorescent tube support, comprising:

an integral body formed from synthetic resin sheet material having a thickness prior to forming of from about 0.013 to 0.018 inch, said body having a front margin presenting an elongated, laterally extended lowermost surface, concavo-convex walls defining a number of elongated, open-top, parallel, juxtaposed, concave tube-receiving regions and corresponding convex underside wall surfaces, with elongated top walls between juxtaposed upwardly opening regions,

said region-defining walls including a first plurality of axially spaced apart, upwardly opening and diverging tube-engaging arcuate first wall sections each having a radius generally conforming with the circular sidewall of a fluorescent tube, and a second plurality of axially spaced apart, downwardly opening and diverging tube-engaging arcuate second wall sections each having a radius generally conforming with the circular sidewall of a fluorescent tube,

said upwardly opening first wall sections and said downwardly opening second wall sections alternating along the length of each of said regions,

the lateral ends of said downwardly opening wall sections being at the vertically lowest extent of said support when the support is horizontally oriented, there being upright wall sections interconnecting said first and second wall sections,

said first and second tube-engaging wall sections each being formed with undulating tube-engaging surfaces; and

spacer means for preventing complete nesting of plural supports and to define substantially uniform, elongated, laterally extending spaces between adjacent interfitted supports for insertion of automatic dispensing equipment therebetween, said spaces having a vertical height of at least about 1/8 inch, said spacer means including structure for creating a vertical space between the top walls of adjacent interfitted supports in a stack thereof to facilitate separation of individual supports from said stack.

2. The tube support as set forth in claim 1, said first and second tube-engaging wall sections each having a plurality of elongated, side-by-side ribs formed therein.

3. The tube support as set forth in claim 1, said top walls being slightly thicker than said second wall sections.

4. The tube support of claim 1, said spacer means comprising an elongated, rearwardly extending rear side lip having an underside presenting an abutment surface, and a plurality of upstanding, laterally spaced apart nibs carried by said lip, said nibs having a vertical height of at least about 1/8 inch.

5. The tube support of claim 1, said spacer means including structure presenting a plurality of laterally spaced apart ledge platforms oriented along the front side edge of the support and positioned for preventing complete nesting of plural supports.

6. The tube support of claim 1, said sheet material being polyvinyl chloride.

7. The tube support of claim 1, the distance between the longitudinal axes of certain adjacent pairs of said tube-receiving regions being slightly different than the distance between the longitudinal axes of other adjacent pairs of said tube-receiving regions.