Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-01-21
2002-10-15
Wallerson, Mark (Department: 2722)
Facsimile and static presentation processing
Static presentation processing
Attribute control
51, 51
Reexamination Certificate
active
06466332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a black color generation amount determining method in black printing, a black color generation amount determining apparatus in black printing and a media having recorded thereon a black color generation amount determining program in black printing.
2. Description of the Prior Arts
Various methods have conventionally been proposed for determining a black color component in performing black printing, one of which is proposed in “Theory and Practice of Black Printer” at Electrostatic Society Magazine, Vol. 3, No. 3, pp.67 to 75.
The basic idea of black printing is such that an undercolor amount which is a common minimum component is obtained based upon tone data of so-called CMY (cyan, magenta, yellow) to calculate K (black) component by multiplying the undercolor amount by a constant number called a black generation ratio (BGR), while a predetermined ratio (UCR ratio) is multiplied to the K component in order to replace the CMY component with the K component for attaining decreased amount.
On the other hand, Japanese Laid-Open Patent Application No. HEI 7-87347 discloses a method for determining an UCR ratio based upon chroma upon performing such black printing.
Black printing is put to practical use in a color printer connected to a computer, wherein K dot is marked with CMY dot.
The principal objective in the above-mentioned conventional method for determining a black color component is to prevent color difference from being generated. A remarkableness of dot is liable to become a problem above the color difference for a device having a relatively large dot diameter such as a color printer. On the other hand, there may frequently be the case where colors are different from one another even if they have the same undercolor amount. It has been known that the remarkableness of each K dot is different, when these different colors are printed by the color printer.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a black color generation amount determining method in black printing capable of making K dot unremarkable including a color printer.
The black color generation amount determining method in black printing according to the present invention is constructed such that, upon generating a black color component in order to perform black printing in a color space for printing comprising a plurality of approximately equivalent element colors, the black color component is caused to be generated to have a predetermined relationship with respect to a gray component in the plurality of element colors, and that the brighter a color is, the more the generation amount decreases.
In the present invention having the aforesaid construction, the black color component is caused to be generated to have a predetermined relationship with respect to the gray component in the plurality of element colors upon performing black printing in the color space for printing comprising the plurality of approximately equivalent element colors. The generation amount of the black color component varies not only in accordance with the gray component, but also in relation to brightness of data before conversion, that is, the brighter the data before conversion is, the less the black color component generates. Accordingly, the generation amount of the black color component is decreased in the brighter color even if the gray component is the same, thereby making the black color component unremarkable.
Therefore, the present invention can provide the black color generation amount determining method capable of making dot unremarkable, since the present invention places great importance on not only the viewpoint of the color difference but also the viewpoint of the remarkableness of dot in black printing to control the generation amount of the black color component with respect to a bright color.
Various deciding methods can be adopted to the gray component which is the basis for generating the black color component. Another object of the present invention is to provide a more specific deciding method of the gray component.
In the black color amount determining method in black printing according to the present invention, the gray component is decided based upon an undercolor amount which is a common minimum component in the plurality of element colors.
In the present invention having the aforesaid construction, the gray component is decided based upon the obtained undercolor amount which is the common minimum component in the plurality of element colors. The undercolor amount in a narrow sense corresponds to minimum tone data if, for example, the plurality of element colors are expressed by CMY and the undercolor amount is afforded as the tone data representing the densities of CMY. However, the undercolor amount is not limited to the one in a narrow sense. For example, there has been known a method as an undercolor removal in which the undercolor amount obtained in this way is simply replaced with the black color component for subtracting the component value of each element color by the replaced value. In this case, the element color of the minimum component value is originally not utilized at all. However, it has been known that chroma is decreased in the aforesaid method. Therefore, a method of an undercolor addition may actually be performed to add a predetermined component amount to each of the element colors after subtracting the undercolor amount. Accordingly, an experiential compensation may be added to the undercolor amount, so that the undercolor amount which is the common minimum component in the plurality of element colors is merely used as the basis of the gray component. The present invention includes the undercolor amount suitably increased or decreased.
In this way, the present invention can provide the black color generating amount determining method capable of deciding the gray component in a relatively simple manner.
It should be noted that the method of the undercolor removal or undercolor addition may be adopted in the present invention. In this case, the undercolor removal amount can be varied related to unfixed generation amount of the black color component. For example, upon generating the black color component while determining the undercolor removal amount for subtracting the component amount of each element color based upon the undercolor amount, the undercolor removal amount may be determined to be great as the generation amount of the black color component increases. In such a construction, the undercolor removal amount varies with the variation of the actual generation ratio of the black color component since the generation ratio of the black color component varies in accordance with brightness, whereby the balance as the undercolor amount is maintained.
Brightness of a color is the basis for determining the generation amount of the black color component. The tendency may show that the brighter the color is, the more the generation amount decreases. Therefore, the basis can include the other factors than brightness.
Therefore, further object of the present invention is to provide a black color generation amount determining method in black printing capable of having a basis including other factors than brightness.
The black color generation amount determining method in black printing according to the present invention has the construction for deciding by adding chroma as a guideline of bright color to brightness.
In the present invention having such a construction, the greater chroma is, the greater the index of brightness is by adding chroma to the index of brightness, with the result that the generation amount decreases. On the other hand, the smaller chroma is, the smaller the index of brightness becomes, so that the generation amount increases. When this construction is adopted, the generation amount of the black color component increases in the portion of nearly gray having low chroma, while it decreases in a bright portion.
Therefore, according to the present invention, the
Seiko Epson Corporation
Sughrue & Mion, PLLC
Wallerson Mark
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