Facsimile and static presentation processing – Static presentation processing
Reexamination Certificate
1998-07-10
2001-11-20
Moore, David (Department: 2624)
Facsimile and static presentation processing
Static presentation processing
C358S504000, C358S518000
Reexamination Certificate
active
06320668
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for COLOR CORRECTION APPARATUS AND METHOD IN AN IMAGE SYSTEM earlier filed in the Korean Industrial Property Office on the 10
th
of July 1997 and there duly assigned Serial No. 31875/1997.
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a color correction apparatus and method thereof in an image system and, more particularly, to a color correction apparatus and method thereof in an image system capable of automatically processing the color correction by storing reference colorimetric data regarding a predetermined test pattern for estimating the color correction in a storage medium, and then scanning the test pattern so that the color correction can be performed by minimizing an error between the reference data and the scanning data obtained by scanning the test pattern.
2. Related Art
Conventionally, an image system is a system which acquires, processes, outputs, converts, transmits, improves, etc. image signals in compliance with an aim. As examples of the image system, a printer and a scanner are publicly well known and widely used. In addition, a multifunctional machine which integrates the printer and scanner functions, and which performs a document output function is a good example of an image system.
Such multi-functional machines include a scanner which, after radiating and illuminating light having a certain spectrum toward an object such as a document, performs photoelectric conversion which converts optical information reflected from the object into an electrical signal, thereby acquiring image information. A printer is also an essential component part in multi-functional machines, and the recent development of color printers has led to the printing of multicolor images by the use of plural toners or plural ink cartridges. As the supply color printer has increased, high quality or high definition printing has become prevalent in color printing. The color image is obtained through a color resolution process which employs color reproduction characteristics of a color image obtained from a spectral optical system.
As discussed in more detail below, waveforms illustrating the visual characteristic of the human optical system and the spectral characteristic of an image system are important in obtaining color reproduction in modern image systems. Moreover, a color correction process is performed by allowing the visual characteristic of the human optical system to be aligned with or to correspond to the spectral characteristic of the image system. Such a color correction process is typically performed by mathematical operations which are very complicated. As also discussed in more detail below, three methods are employed: a linear transformation method; a polynomial transformation method; and a three-dimensional look-up table method. Of these three methods, certain methods are more accurate than others, and certain other methods are more costly than others. Thus, a particular method must be chosen based on the objective to be achieved, for example, cost or accuracy.
Through a use of a color correction apparatus and method in an image system, color correction is to a certain degree accomplished by correcting the spectrum characteristic of the spectral optical system and the individual variation in light quantity. However, the apparatus and method cannot properly cope with the age-based variation generated by the operating conditions or the environmental differences when performing color correction.
In addition, in an image system, the color image input unit is attached to other image devices having different color reproduction characteristics (such as a monitor, printer or a communication device). Since the color reproduction characteristics of each image device are different, technology capable of performing a device-independent color correction procedure is needed.
Therefore, there is a need for the development of a color correction method and apparatus which adaptively performs color correction according to a spectrum characteristic of a spectral optical system, age-based variation and individual variation in light quantity. That is, there is a need for the development of a color correction method and apparatus which performs color correction without regard to the spectrum characteristic of the spectral optical system, age-based variation, and individual variation in the light quantity.
There is also a need for the development of a color correction method and apparatus which is capable of performing gray level correction prior to performing color correction in order to acquire linearity of gray level characteristics regarding each spectrum of the primary colors (red, green and blue).
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to perform color correction adaptively according to a spectrum characteristic of a spectral optical system, age-based variation and individual variation in the light quantity in order to perform color correction without regard to the spectrum characteristic of the spectral optical system, age-based variation and individual variation in the light quantity. Color correction is performed in order that the spectrum characteristic have a linear relation to the visual characteristic of a human being. Preset reference colorimetric data regarding a test pattern for measuring the color correction is stored in a storage medium, and the color correction process is performed in order to reduce an error between scanning data obtained by scanning the measuring test pattern and reference colorimetric data to a minimum, thereby scanning a prescribed measuring test pattern document. As a result, the color correction process is automatically performed.
It is another object of the present invention to provide a color correction apparatus and method thereof in an image system capable of performing gray level correction prior to performing color correction in order to acquire the linearity of gray level characteristics regarding each spectrum of RGB colors.
According to one aspect of the present invention, the color correction apparatus of the image system, which includes a photoelectric conversion unit which radiates an illuminating light having a certain light emitting spectrum to an object and which outputs the spectral information regarding the RGB colors reflected from the object after converting it into electrical signals, includes: a reference data storage unit which stores reference gray level data and reference colorimetric data measured from an achromatic test pattern and a chromatic test pattern of a preset test pattern, respectively, by accumulating the data in the database system; a correction coefficient calculating unit, including a color correction coefficient calculating unit which calculates a color correction coefficient matrix, for reducing an error between colorimetric scanning data and the reference colorimetric data to a minimum according to a certain color correction method after receiving the colorimetric scanning data obtained by scanning the chromatic test pattern through the photoelectric conversion unit; and a color correction unit, including a color correction processing unit which receives the color correction coefficient matrix from the correction coefficient calculating unit, for performing a linear transformation applying the color correction coefficient matrix to an output of the photoelectric conversion unit, and then for outputting the result after converting into a certain color coordinate system.
Preferably, the correction coefficient calculating unit further includes a gray level correction coefficient calculating unit for calculating a gray level correction coefficient matrix which reduces an error between gray level scanning data and the reference gray level data to a minimum after receiving the gray level scanning data obtained by scanning the achromatic test pattern through the photoelectric conversion u
Bushnell , Esq. Robert E.
Kianni K C
Moore David
Samsung Electronics Co,. Ltd.
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