Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-07-24
2001-10-23
Coles, Edward (Department: 2853)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S001110, C358S515000, C358S518000, C358S520000, C358S525000, C358S519000, C382S276000
Reexamination Certificate
active
06307644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing method and an apparatus for performing color processing by using interpolation processing, and a recording medium.
2. Description of the Related Art
Hitherto, representative of this type of apparatus, a color correction processing apparatus is known, such as a color ink jet printer, for performing recording by causing ink to be deposited onto a surface. In such apparatuses, for example, it is necessary to provide an input signal in the form of luminance signals of R (red), G (green) and B (blue) which are dependent upon a device, and to obtain density signals corresponding to each of the colors C (cyan), M (magenta), Y (yellow) and K (black) as output signals. Also, by taking the portability of image data into consideration, in such a processing system a method has recently been proposed in which an input signal is once converted into a color space, which is not device dependent, such as the CIE 1931 XYZ color space or the CIE1976LAB color space, determined by the Commission Internationaldel Eclairage (abbreviated as CIE), and converted into a density signal dependent upon an output device. At this time, the color correction processing apparatus must perform many processes (the details of which are omitted here), as shown in FIG.
2
.
Accordingly, a method is proposed in, for example, Laid-Open Japanese Patent Nos. 7-193723 and 8-237497, in which the results, such that this series of processing is performed in advance on a specific input signal, are stored in a N-dimensional look-up table (LUT), and an interpolation computation is performed by referring to the LUT, thereby obtaining an output signal corresponding to a desired input signal.
Since all of these methods take an orthogonal coordinate system of RGB and the like as an input signal and obtain an output signal by linear interpolation, there is the drawback of the interpolation accuracy being poor.
Meanwhile, in Laid-Open Japanese Patent No. 5-46750, a method is proposed in which an RGB input signal is converted into hue, chromaticity and brightness, and this is interpolation-computed by referring to a two-dimensional or three-dimensional LUT, thereby obtaining an output signal corresponding to a desired input signal. In these methods, the object is to increase the accuracy by converting an input signal into a signal appropriate for a visual characteristic. However, in the former case conversion into a polar coordinate system must be performed, and in the latter case conversion into a YCrCb coordinate system must be performed, giving rise to the drawback of the processing becoming heavily loaded.
Also, in Japanese Patent Publication No. 7-119128, as a method for converting an RGB input signal into hue, chromaticity and brightness, a method simplified by comparing the relationship of the RGB input signals is proposed. However, in these proposals, since many processes, such as those shown in
FIG. 2
, are not considered, there is the drawback that an interpolation computation using a LUT cannot be performed.
As described above, each of the conventional technologies has drawbacks such as the interpolation accuracy being poor, and the processing becoming heavily loaded.
SUMMARY OF THE INVENTION
An object of the present invention, which is achieved in view of the above-described points, is to perform image processing with enhanced accuracy without requiring complex processing.
To achieve the above-described object, according to one aspect of the present invention, there is provided an image processing method, including the steps of: converting an input signal into first and second color components and a component indicating brightness; referring to a look-up table on the basis of the first and second color components and the component indicating brightness, and reading a plurality of color-component data from the look-up table dependent upon an output device; and performing interpolation processing on the basis of the plurality of color-component data dependent upon an output device, and generating output device dependent color-component data corresponding to the input signal.
According to another aspect of the present invention, there is provided an image processing method, including the steps of: inputting an image signal formed of three components; generating a brightness component, and two color components on the basis of minimum data of the three components; referring to a look-up table on the basis of the brightness components and the two color components, and reading a plurality of color-component data from the look-up table dependent upon an output device; and performing interpolation processing by using the color-component data dependent upon the output device, and computing output device dependent color-component data corresponding to the image signal.
Other objects, features and advantages of the invention will become more apparent from the following detailed description given in conjunction with the accompanying drawings.
REFERENCES:
patent: 5311332 (1994-05-01), Imao et al.
patent: 5315415 (1994-05-01), Kawai et al.
patent: 5768410 (1998-06-01), Ohta et al.
patent: 0168818 (1986-01-01), None
patent: 0551773 (1986-01-01), None
patent: 0551773 (1993-07-01), None
patent: 5046750 (1993-02-01), None
patent: 7193723 (1995-07-01), None
patent: 8237497 (1996-09-01), None
Canon Kabushiki Kaisha
Coles Edward
Fitzpatrick ,Cella, Harper & Scinto
Lamb Twyler
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