Character-based monochromatic representation of color images

• US 4,703,318 A
• Filed: 04/16/1985
• Issued: 10/27/1987
• Est. Priority Date: 03/30/1984
• Status: Expired due to Term

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: Wang Laboratories Incorporated
• Inventors: Haggerty, William T.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/723,732
• Time in Patent Office: 924 Days
• Field of Search: 340/703, 340/793, 340/729, 340/734, 340/722, 340/730, 340/731, 340/723, 340/724, 340/750, 340/798, 340/799, 358/22, 358/81, 358/283, 358/298, 350/162.12
• US Class Current: 345/634
• CPC Class Codes: G06K 15/00 Arrangements for producing a permanent visual presentation of the output data , e.g. computer output printersprinting or plotting combined with another operation, e.g. with conveying, G06K17/00
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: G06K 2215/0094 Colour printing
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 5/028 Circuits for converting colour display signals into monochrome display signals
• CPC Class Codes: H04N 1/40012 Conversion of colour to monochrome

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).

Claims

1. A method of forming a monochromatic image from a digital representation of a color image, said monochromatic image being formed on a character-based output device having a loadable font memory for storing a library of up to a predetermined maximum number of font patterns, comprising the steps of:

forming a character-based representation of said color image in which a plurality of color characters each describe the background and foreground color within a defined area of said color image,

providing a plurality of color pattern masks each corresponding to a color in said 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,

transforming said color characters to monochromatic characters by replacing the background and foreground colors of each said color character with the corresponding pattern of light and dark dots, said transforming including defining and loading, as required by the formation of the particular monochromatic image, at least some of the font patterns in the font memory, and

displaying said monochromatic characters on said character-based output device.

2. The method of claim 1 wherein said monochromatic characters each comprise a matrix of pixels and each matrix of pixels is represented in a memory as a corresponding matrix of bits.

3. The method of claim 2 wherein said providing step comprises providing a color-pattern matrix of bits to represent each said color pattern mask, with a bit in one state representing at least a portion of a light dot and a bit in the other state representing at least a portion of a dark dot.

4. The method of claim 3 wherein said transforming step comprises the steps of

generating 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,

combining said foreground-background matrix with the color-pattern matrix of the foreground color in such a manner as to replace the bits in said foreground-background matrix with the bits in said color-pattern matrix in areas of foreground color,

combining said foreground-background matrix with the color-pattern matrix of the background color in such a manner as to replace the bits in said foreground-background matrix with the bits in said color-pattern matrix in areas of background color.

7. The method of claim 1 wherein said step of forming a character-based representation of said color image comprises decoding a stream of characters representing a videotext image.

8. The method of claim 1 wherein said transforming and displaying steps include the step of comparing a newly generated monochromatic character to a library of monochromatic characters and adding the newly generated character to the library only if it is not already present there.

9. The method of claim 1 wherein said library is a dedicated character memory in circuitry controlling said output device.

10. The method of claim 8 further comprising the step of detecting redundancies in said monochromatic characters and adding only one character to said library instead of one for each redundant character.

11. The method of claim 10 wherein the redundancies processed in this manner include the presence of a space character (all background or all foreground) as one of a plurality of monochromatic characters corresponding to a single alphanumeric color character.

12. The method of claim 1 wherein fewer of said color pattern masks are provided than there are colors in said color image and each color for which no pattern mask is provided is represented as the inverse of one of said patterns by instructing said output device to display a character containing said color in a reverse video manner.

13. The method of claim 4 wherein

in said providing step fewer of said color pattern masks are provided than there are colors in said color image and each color for which no pattern mask is provided is represented as the inverse of one of said patterns and

in said displaying step monochromatic characters containing areas for which said inverse patterns are required are displayed in reverse video.

14. The method of claim 13 wherein 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 in said transforming step by doing the inversion of color pattern during the transformation.

5. A method of forming a monochromatic image from a digital representation of a color image, said monochromatic image being formed on a character-based output device of a digital computer, comprising the steps of:

forming a character-based representation of said color image in which a plurality of color characters each describe the background and foreground color within a defined area of said color image, wherein said color characters include alphanumeric characters having the foreground color in the body of the character and the background color elsewhere, and wherein said color characters also include graphical characters,

providing a plurality of color pattern masks each corresponding to a color in said 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,

transforming said color characters to monochromatic characters by replacing the background and foreground colors of each said color character with the corresponding pattern of light and dark dots, said transforming including

generating for each graphical color character at least two monochromatic characters which together represent a scaled form of the graphical color character, and

generating for each alphanumeric color character at least two said monochromatic characters one of which is a space character (all background) and another which includes the body of said alphanumeric character,

displaying said monochromatic characters on said character-based output device.

6. The method of claim 5 wherein 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.

16. The method of claim 5 wherein the graphical color characters are of a type having two vertical rows of blocks and wherein said transforming step includes forming a first monochromatic character containing one said vertical row of blocks and forming a second monochromatic character containing the other said vertical row of blocks.

15. A method for transforming a color image into a monochromatic image, comprising the steps of:

providing a plurality of color pattern masks, each color pattern mask corresponding to a color in the original image and comprised of a pattern of light and dark dots, wherein

each pattern is selected, in relation to all other patterns, to provide gray scale and textural visual impressions providing discrimination between areas of the monochromatic image in a manner analogous to the corresponding original image colors, and

replacing the color in each area of the color image with the corresponding color pattern mask dot pattern, wherein said color pattern masks comprise

space="preserve" listing-type="tabular">______________________________________ for black, the pattern 1111111111 1111111111, for white, the pattern 0000000000 0000000000, for blue, the pattern 1000000000 0000010000, for yellow, the pattern 0111111111 1111101111, for red, the pattern 1000100010 0010001000, for cyan, the pattern 0111011101 1101110111, for green, the pattern 1000110001 0101001010, and for magenta, the pattern 0111001110 1010110101. ______________________________________