The present invention relates to a method and apparatus for printing in color and, more particularly, to a method of adjusting color files to print acceptable color graphics upon printing apparatuses having limited color capability.
Many receipt-type printers have limited color printing capability, such as printing receipts in two colors. Those individuals who desire to print multiple color bitmap graphics on this type of color-limited printer will obtain an output that is generally unacceptable in terms of quality and visual appeal. The present invention seeks to provide a method of adjusting color bitmap files, to provide visually acceptable output for the average user when the images are rendered on a printer with limited color printing capability.
The current invention includes a method of reducing the number of colors in a color bitmap file. The method reflects the discovery that when a logo or graphic is automatically or computer-reduced in color quantity, the result is often unsatisfactory to the average viewer. The method of the invention comprises a combination of programmatic and manual color reducing routines that reduces the bitmap to a smaller number of colors. The color reducing routines are arranged in two stages. A first stage of the color reducing routines automatically reduces the bitmap file to fewer than a specified number of colors. A second stage of the color reducing routines then allows the individual user to manually map the reduced color bitmap to colors supported by the printer. It has been discovered that manually reducing the file to the limited number of colors of a two-color printer will often provide an image with acceptable visual result for the viewer.
U.S. Pat. No. 6,206,504 for METHOD AND APPARATUS FOR TWO-COLOR INK JET POINT OF SALE (POS) PRINTING issued to Stephen R. Payne describes a two-color ink jet point of sale printer that includes a converter for converting full color printing commands into commands for printing in two colors: a primary color and an alternate color.
In accordance with the present invention, a method is provided for printing multi-color graphics in a limited number of colors. Despite the new limited color capability, the invention results in a visually acceptable product. The advantage of using the method of this invention is that it allows users to print graphics on printers with limited (two-color) capability. The method comprises a split program routine, wherein a first stage automatically reduces the number of colors contained in a bitmap. The second stage allows the user to further manually map the color file to fit the color printing limitations of the printer. The first stage of the program routine contains a color-reducing algorithm, in which parameters are set to control the color reduction process and define the resultant number of colors. The algorithm automatically converts the file to a smaller number of colors, and then the program presents the user with a split screen containing color swatches of the bitmap.
On one side, the first template of colors contains all of the colors remaining in the reduced-color bitmap. Adjacent thereto, the second template of colors contains the colors according to the printing capability of the printer being used. In the case of a receipt or Point Of Sale (POS) printer, such printing would contain only two sets of colors: for example, black and red or black and blue, plus white, the color of the paper. Selected dithered combinations of these colors can also be printed. The user then maps each color area in the first template to one in the second template, in order to reduce the colors to the limited color capacity of the printer. Different colors in the first color template may map to the same printing color in the second template.
Upon mapping all of the colors, the program converts all of the colors in the image to the chosen colors: the final image is illustrated on the screen. The user can then save the image in a variety of formats and/or print the image.
A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent detailed description, in which:
For purposes of brevity and clarity, like components and elements of the programming screen method of this invention will bear the same designations or numbering throughout the figures.
Generally speaking, the invention features a program method of converting a multiple color file to a two-color or limited-color file, so that an image contained therein can be printed upon a receipt, Point Of Sale, or two-color printer. Many multiple color graphic files cannot be acceptably reduced in color by automatic methods. The program method of this invention contains a second-stage routine that requests user participation and input. The resulting printed image is visually acceptable by reason of this user input.
Now referring to
The image 12 may have to be resized to fit a particular printer. This can be accomplished by clicking upon Step 2. After resizing, the user clicks the mouse on Step 3, box 16, which modifies the color data in the file, so that the image 12 can be printed upon a printer having limited color printing capabilities (i.e., can print in only a small number of colors). Such limited color printing machines are typically those that print receipts, are used at Point Of Sale, and which generally print in two colors. Of course it should be understood that any of a limited number of colors can be used.
Upon clicking Step 3 box 16, the form 18, shown in
The aforementioned programmatic color reduction process is performed by a three-step algorithm, as follows:
a) count the pixels of each color in the original image or bitmap;
b) convert the pixels in the image or bitmap of the least common color to one of the other colors (i.e., the color that is closest in RGB color space); and
c) repeat step (b) until the number of resultant colors is no greater than the number of colors specified by the user in box 20 (
At this point, the first stage of the program method of this invention is complete. The color image 12 is now automatically reduced to the specified number of colors. The monitor 11 displays the image 13 in the reduced colors, as shown in
The method of this invention also provides for user (manual) input, with two-color adjustment being provided by a second stage in the program routine. The second stage is described hereinafter, with reference to
Different colors in the left side 35 of the multiple color template 25 may map to the same printing color (swatch) on the right side 45.
The procedure for mapping the colors is as follows: (i) the user clicks for example on swatch 27 on left side 35 of template 25; (ii) thereafter, the user clicks on a color swatch, for example 44 on the right side 45 of the template 25; (iii) the program now draws a line 50 between swatch 27 and swatch 44, and places an “X” in the swatch 27 to indicate that this color has been mapped; and (iv) the user then proceeds to map all of the remaining swatches 28, 29, etc. on the left side 35 of the template 25.
Upon mapping all of the colors, the program converts all of the colors in the image 12 to the chosen colors. The final image 60 is illustrated on the screen 11, as shown in
Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.
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Number | Date | Country | |
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20020171851 A1 | Nov 2002 | US |