Computer graphics processing and selective visual display system – Display peripheral interface input device
Reexamination Certificate
1998-01-20
2001-11-06
Brier, Jeffery (Department: 2672)
Computer graphics processing and selective visual display system
Display peripheral interface input device
C345S440000
Reexamination Certificate
active
06313823
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to computer display monitors and relates more particularly to a system and method for accurately measuring the color output of a computer monitor.
2. Description of the Background Art
Accurate measurement of color displays is a significant consideration for manufacturers, designers, and users of computer devices. When computer users send images to a printer device, it becomes important to accurately specify individual colors so that the resulting printed material exactly matches the colors shown on the computer monitor screen. Further, when image data from one display monitor is displayed on a different monitor, the image data may be displayed with different colors because of the type of computer monitor, the video display circuitry, and various other related factors.
Conventionally, to obtain a measurement of the color output of a computer monitor, a system user has to select a sufficiently large area on the computer monitor screen, or enlarge a smaller area of the computer monitor screen, and then position a photometer device to sense the selected area of the monitor screen. This method is both time-consuming and cumbersome. An easier and faster, but potentially less accurate method uses a software routine to determine the color output of the computer monitor. After the user selects an area of the computer monitor screen for measurement, the software routine uses a lookup table to estimate what the color output should be, based on monitor parameters (for example model or type) entered by the system user.
While this software method is slightly more convenient when compared to the previous method (because a separate external device like a photometer is not required), it is still relatively inconvenient to the system user because it requires the system user to correctly enter the relevant monitor parameters. Further, this method may be inaccurate because it depends on a predetermined estimate of color output, based on the computer monitor parameters.
Additionally, without correct color output measurements, printer devices may have difficulty printing accurate colors based solely on a picture from a computer. Intermediate proofs may be required to verify the accuracy of the colors, and special inks may have to be formulated manually. These procedures are both likely time-consuming and expensive. Therefore, for all the foregoing reasons, an improved system and method are needed to measure the color output of a computer monitor, in accordance with the present invention.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system and method are disclosed for accurately measuring the color output of a computer monitor. This invention accurately measures the color output by using factory-calibrated phosphor characteristics (phosphor characteristics determine the amount of displayed color per ampere of beam current), and then developing a correlation between beam current in the monitor and pixel values. The invention is composed of a system and method that establishes the relationship between beam current and pixel values; accesses the factory-calibrated phosphor characteristics; determines the beam current in the display based on the pixel values of an area of the computer screen selected by the system user; and multiplies the beam current by the phosphor characteristics to yield an accurate measurement of the color output. An additional function of the system and method is to yield an accurate Pantone Color simulation of the color output by searching a database of PANTONE colors.
In the preferred embodiment of the present invention, a calibration routine first creates a lookup table. In practice, the system first calibrates the monitor so that a pixel value of zero results in a beam current of zero. Second, the system then generates a flat white field on the monitor display and then measures the red, green and blue pixel values and the associated red, green, and blue beam currents. Third, the system then generates a gray field on the computer monitor screen and again measures the red, green, and blue pixel values and the associated beam currents. Creating a graph with pixel values on the x axs and beam current on the y axis, two data points can be plotted for each color (one point measured when the flat white field was generated, and one point measured when the gray field was generated). From these two data points (beam current plotted against pixel value) for each color, exponential curves may be created to provide a beam current corresponding to each pixel value. Separate exponential curves are generated for each color to yield red beam current measurements for red pixels; green beam current measurements for green pixels; and blue beam current measurements for blue pixels. These beam current and pixel values are then stored into a lookup table for future reference.
In the next step, the user selects an area of the computer monitor screen to be analyzed. To select the area, the user first places the cursor over a selected pixel on the computer monitor. This then becomes the origin pixel. The user next selects an aperture size. The aperture size is a measure of the area surrounding (and including) the origin pixel. In the preferred embodiment, the aperture size ranges from one pixel, in which case only the origin pixel will be measured, to thirteen-by-thirteen pixels. The system next separately averages the red, green, and blue pixel values in the user-specified aperture area. Each pixel value has a red, green, and blue component. So, for example, the average red pixel value consists of the sum of the red components of each pixel in the selected area divided by the total number of pixels in the selected area. This averaging procedure is repeated for the green and blue pixel values.
The system next determines the beam current associated with the average red, green, and blue pixel values, by referring to the predetermined lookup table. The system then fetches the phosphor characteristics internally stored in the monitor's memory and multiplies the phosphor characteristics by the beam current previously determined for each color. The results are then converted into a user-specified format and displayed. Formats supported preferably include RGB, CIE 1931, CIE 1976, CIE L*a*b*, and Thstimulus color spaces.
In addition, the above results may then be matched to a PANTONE Color. In the preferred embodiment, the present invention performs a search through a PANTONE Color database to determine the closest matches. The three closest matches are preferably then displayed on the computer monitor. PANTONE Colors are useful because they are a reference standard. They allow the user to specify the specific color to be used in a printer device, and by having an accurate PANTONE Color, the correct color can be specified directly to the printer device. Therefore, there is no need for preparing intermediate proofs, or for manually formulating ink. Accordingly, the present invention more accurately and efficiently measures the color output of a computer display.
REFERENCES:
patent: Re. 33973 (1992-06-01), Kriz et al.
patent: 4709267 (1987-11-01), Sendelweck
patent: 4733229 (1988-03-01), Whitehead
patent: 4876663 (1989-10-01), McCord
patent: 4907174 (1990-03-01), Priem
patent: 5150107 (1992-09-01), Kurisu
patent: 5204748 (1993-04-01), Lagoni
patent: 5313291 (1994-05-01), Appel et al.
patent: 5386247 (1995-01-01), Shafer et al.
patent: 5394067 (1995-02-01), Santelmann, Jr.
patent: 5396151 (1995-03-01), Cappels, Sr.
patent: 5469540 (1995-11-01), Powers, III et al.
patent: 5473371 (1995-12-01), Choi
patent: 5493317 (1996-02-01), Kim
patent: 5497436 (1996-03-01), Miller
patent: 5512961 (1996-04-01), Cappels, Sr.
patent: 5550443 (1996-08-01), Lee
patent: 5550556 (1996-08-01), Wu et al.
patent: 5555026 (1996-09-01), Lee
patent: 5561459 (1996-10-01), Stokes et al.
patent: 5564002 (1996-10-01), Brown
patent: 5570108 (1996-10-01), McLaughlin et al.
patent: 5574507 (1996-11-01), Baek
patent: 5579029 (1996
Cappels Richard
Devine Jesse
Apple Computer Inc.
Blackman Anthony J.
Brier Jeffery
Carr & Ferrell, LLC
LandOfFree
System and method for measuring the color output of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for measuring the color output of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for measuring the color output of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2575976