Image analysis – Color image processing
Reexamination Certificate
1997-07-17
2001-05-01
Mancuso, Joseph (Department: 2723)
Image analysis
Color image processing
Reexamination Certificate
active
06226397
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus, method, and computer readable memory for processing input image data.
As an example of a conventional color image processing apparatus, color processing in a color copying machine is described below with the aid of FIG.
17
.
Reference numeral
101
denotes a color image input unit such as an image reader unit of the color copying machine. In addition, the color image input unit
101
includes an original image reading device such as a color image scanner, an image input unit from a computer in a broad sense, and the like.
The color image input unit
101
outputs three color-separated signals R
1
, G
1
, and B
1
which are obtained by color-separating each pixel of a color image into R, G, and B components. The three color-separated signals R
1
, G
1
, and B
1
are input to an achromatic color/chromatic color determination unit
102
. The unit
102
determines if the pixel of interest is a monochrome (achromatic color) pixel or a color (chromatic color) pixel, and outputs a determination signal KC to a color correction unit
107
on the basis of the determination result. The signal G
1
of the three color-separated signals is input to a character/image determination unit
104
, which checks if the pixel of interest corresponds to a line image such as a character, thin line, or the like, or a continuous-gradation image such as a picture image, printed image, or the like. The unit
104
outputs a character/image determination signal TI on the basis of the determination result.
The character/image determination signal TI is input to a spatial filter coefficient storage unit
105
. When the corresponding pixel corresponds to a character signal, character spatial filter coefficients
1601
(see
FIG. 18
) are selected and output; when the corresponding pixel corresponds to an image signal, image spatial filter coefficients
1602
(see
FIG. 18
) are selected and output.
Conventional spatial filter processing including edge emphasis and the like is explained below.
FIG. 18
shows examples of the character spatial filter coefficients
1601
and image spatial filter coefficients
1602
described in FIG.
17
and each defined by a 5×5 pixel matrix. The character spatial filter coefficients
1601
are determined to effect stronger edge emphasis for an image than the image spatial filter coefficients
1602
. Character or image spatial filter coefficients Kij selected in accordance with the character/image determination signal TI are set in a spatial filter
103
including R, G, and B spatial filters
103
R,
103
G, and
103
B for R, G, and B signals. The individual spatial filters edge-emphasize the three color-separated signals R
1
, G
1
, and B
1
to output three edge-emphasized color-separated signals R
2
, G
2
, and B
2
.
FIG. 19
shows an example of the detailed arrangement of the R spatial filter
103
R.
A dotted frame
1701
represents a data delay circuit arranged in the R spatial filter
103
R and including line memories
801
to
804
. The signal R
1
is input to the R spatial filter
103
, and the line memories
801
to
804
store image data for four lines. The stored image data for four lines and image data for the line of interest, i.e., image data for a total of five lines, are sequentially input to flip-flops in units of lines to output data (Xj
1
to Xj
5
) for five successive pixels. The signal R
1
for 5 lines×5 pixels, i.e., a total of 25 signals R
1
, are input to an edge emphasis calculation circuit (R edge emphasis section) indicated by the next dotted frame
1702
, which respectively multiplies the 25 input signals by spatial filter coefficients (&agr;ij: 1≦i≦5, 1≦j≦5) indicated by a dotted frame
1703
and corresponding to the pixel layout and sums up the products.
The spatial filter processing for an R signal has been described, and the same applies to G and B signals.
The three edge-emphasized color-separated signals R
2
, G
2
, and B
2
are input to a luminance/density conversion unit
106
, and are converted into density signals C
1
, M
1
, and Y
1
by, e.g., log conversion. The density signals C
1
, M
1
, and Y
1
are input to a color correction unit
107
to be subjected to color processing such as generation of a black signal K, undercolor removal, color correction, and the like. As a result of the color processing, density signals C
2
, M
2
, Y
2
, and K
2
are generated. Also, the color correction unit
107
sets the density signals C
2
, M
2
, and Y
2
at C
2
=M
2
=Y
2
=0 in accordance with the determination signal KC as the determination result of the achromatic color/chromatic color determination unit
102
when the corresponding pixel is an achromatic pixel, thereby converting the corresponding pixel into a pixel defined by black color alone.
Reference numeral
110
denotes a color image output unit which comprises an image recording apparatus such as an electrophotographic or ink-jet printer. When the color image output unit
110
is, e.g., a binary printer, the density signals C
2
, M
2
, Y
2
, and K
2
are converted into binary signals C
3
, M
3
, Y
3
, and K
3
by a binarization unit
108
. On the other hand, when the resolution of the image input from the color image input unit
101
is different from that of the image to be output from the color image output unit
110
, the binary pixel signals C
3
, M
3
, Y
3
, and K
3
are subjected to resolution conversion processing by a smoothing/resolution conversion unit
109
to be converted into binary signals C
4
, M
4
, Y
4
, and K
4
. Especially, when the resolution of the color image output unit
110
is higher than that of the color image input unit
101
, smoothing processing for smoothly interpolating edge portions of the image is performed. The binary signals C
4
, M
4
, Y
4
, and K
4
are recorded by the color image output unit
110
.
However, when the input image is a color image, the above-mentioned color image processing apparatus requires spatial filters in correspondence with the R signal (
103
R), G signal (
103
G), and B signal (
103
B). If the input image is a black-and-white or monocolor image, not all the R, G, and B spatial filters need be used to perform spatial filter processing of the input image. For this reason, some spatial filters are wasted.
In order to especially improve the image quality of a monochrome image using a color image apparatus, it is required to improve filter characteristics by increasing the filter size. However, this results in high cost.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above-mentioned problems, and has as its object to efficiently use a plurality of independent processing means.
It is another object of the present invention to provide an image processing apparatus, method, and computer readable memory, which can efficiently use filters by applying a plurality of filters arranged for filtering a color image to a monochrome image. It is still another object of the present invention to efficiently use a delay means for chromaticity signals by using it for delaying a lightness signal.
It is still another object of the present invention to provide an image processing apparatus, method, and computer readable memory, which can broaden the filtering range of filters used for a monochrome image by applying a plurality of filters arranged for filtering a color image to a monochrome image without increasing the circuit scale, and can especially improve the image quality of a monochrome image.
In order to achieve the above objects, an image processing apparatus according to the present invention comprises the following arrangement.
That is, an image processing apparatus for processing input image data, comprises:
a plurality of processing means which can execute parallel processing in units of component data of image data which is made up of a plurality of component data;
selection means for selecting whether the input image data is to be processed as a monochrome image or a color
Kaburagi Hiroshi
Yamagata Shigeo
Canon Kabushiki Kaisha
Cooperrider F. E.
Fitzpatrick ,Cella, Harper & Scinto
Mancuso Joseph
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