Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1989-03-06
1990-12-04
Groody, James J.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358 75, H04N 146
Patent
active
049757695
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
This invention relates to a method for color modification and an apparatus therefor, and more particularly to a method and an apparatus for color modification adapted for making such a color modification to represent a pictorial image represented with first three primary colors by using second three primary colors.
BACKGROUND ART
In the case of dealing with a color pictorial image as data, respective pixels forming that pictorial image are ordinarily represented by the combination of density values of three primary colors. In practice, for three primary colors used, various ones are used depending upon media for dealing with color pictorial image. For example, generally, for displaying a pictorial image on a CRT, etc., three primary colors of the R (Red), G (Green) and B (Blue) system are used, and in the case of printing three primary colors of the C (Cyan), M (Magenta) and Y (Yellow) system are used. In addition, even in the case of three primary colors of the same CMY system, they would become different colors, respectively, in dependence upon the hue peculiar to an ink used in a printing machine or a printer.
As just described above, for permitting the same pictorial image to be dealt with different media, it is required to make a color modification so as to become in conformity with the representation by the three primary colors peculiar to a media used. For such a color modification method, two approaches have been mainly put into practice up to now. The first approach is a method to define a color cube having coordinate axes of the three dimensional rectangular coordinate system on which density values of the three primary colors are taken, respectively, to store modified or corrected data into a storage unit corresponding to the color cube. Data which has not yet modified is used as an address value to provide an access to one point within the color cube defined in the storage unit to read out modified data memorized with respect to this point to thereby make a color modification. This method is disclosed, e.g., in the Japanese Patent Publication No. 16403/77. However, when modified data are stored in respect of all the points within the color cube as stated above, an extensive memory capacity is required. For this reason, a high cost and large capacity memory unit must be prepared. To overcome this drawback, a method for reducing a necessary memory capacity to realize a reduced cost is disclosed in the Japanese Patent Publication No. 25416/80. In accordance with this method, modified data are stored only in respect of representative points within the color cube. Further, when intermediate values between adjacent representative points are needed, an interpolation operation is carried out. Moreover, in a method disclosed in the Japanese Patent publication No. 30222/80, for permitting the memory capacity to be further reduced, only data corresponding to differences between modified data and predetermined reference values are memorized instead of memorizing modified data themselves in regard to respective representative points.
The second approach for the color modification method is a method to use a masking equation. For example, for transforming a pictorial image of the RGB system to a pictorial image of the CMY system, a linear masking equation expressed by values of primary colors, respectively, and a.sub.11 to a.sub.33 are called "linear or first degree masking coefficients", which are parameters to govern transformation, respectively. In this example, these nine parameters are set so that the pictorial image represented by the RGB system and the pictorial image represented by the CMY system are equivalent to each other. Ordinarily, nine parameters are determined by the ratio of the maximum densities of the three primary colors.
Color modification using the linear masking equation has been described as an example. In addition, a method using a quadratic equation to further reduce modification error is also known. In this method, quadratic or second degree terms of R.sup.2, G
REFERENCES:
patent: 4060829 (1977-11-01), Sakamoto
patent: 4819193 (1989-04-01), Imao
Aizu Masao
Hamashima Mitsuhiro
Mukasa Shunsuke
Nakagawa Tsutomu
Uchiyama Takashi
Dai Nippon Insatsu Kaushiki Kaisha
Groody James J.
Powell Mark R.
LandOfFree
Apparatus for color modification adapted to represent the pictor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for color modification adapted to represent the pictor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for color modification adapted to represent the pictor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-886532