JPH0620042A - Method and device for image processing - Google Patents

Abstract

PURPOSE:To obtain the images of high picture quality by controlling the black component value of the character images with no unnaturalness contained in the natural images. CONSTITUTION:The data stored in an image compressing memory 2 are decoded by a data expanding part 3. Meanwhile the CG data are evolved by a CG evolving part 4 and written into an image memory part 7 via a multiplexer MUX 6. The part 4 stores a flag showing the identity of a CG image into the part 8 in response to each picture element position of the image and then synthesizes a natural image and the CG image together at the part 7. Then the image processing parts 10 and 11 perform the color processing operations suited to the natural image and the CG image respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method for outputting an image in which a color natural image and a computer graphics image are mixed to a printer.

[0002]

2. Description of the Related Art Conventionally, the simultaneous presence of a color natural image and a computer graphics (hereinafter referred to as CG) image on the same image has not been performed during the handling of ordinary office documents, except in the field of printing. . Therefore, the image processing unique to each image is not performed, and the same processing is performed over the entire screen to print out (output).

[0003]

However, in order to output an image, a color masking process or the like for correcting the color output characteristic peculiar to the output device is performed, so that the natural image and the CG are output.
If the same processing is performed on the image, the image quality may be deteriorated. For example, in the case of character generation by a character font in CG, the ratio of black characters is very large in a normal office document. Further, human evaluation is strict about the color deterioration of black characters, and the four-color development in which the black generation amount is added is more than the three-color development of Y, M, and C, and the black amount is increased to increase the UCR amount. There is a need. If this is directly applied to the natural image, there is a problem that the image quality is deteriorated.

An object of the present invention is to perform different color processing on a natural image and a CG image, respectively, and increase the UCR amount and smear amount of black characters of a CG image without impairing the image quality of the natural image to enhance the image quality. An apparatus and a method thereof are provided.

[0005]

In order to achieve the above object, the present invention comprises the following constitutions. That is, an image processing device for developing a color natural image and a computer graphics image and outputting them to an output device, a means for setting a flag in a bitmap memory corresponding to each pixel position forming the computer graphics image, And a means for simultaneously performing a predetermined color process on both the image data of the color natural image and the computer graphics image, and a unit for selecting the image after the color process according to the state of the flag.

Preferably, the color processing is performed by a masking circuit for color correction, and only the necessary bits of each color component data are selectively supplied to the masking circuit.

[0007]

With the above construction, the black component amount of the character image is controlled without leaving unnaturalness in the natural image to obtain a high quality image.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 1 is a block diagram showing a circuit configuration of an image processing apparatus according to an embodiment of the present invention. In the figure, the control unit 1 has an operation unit for a human to operate the apparatus, understands the operation contents there to control the operation of all circuits, and has an interface function to an image input / output unit. have. Image reception input section 5
Receives image data from another device, or scans a document image with a scanner (not shown) to capture the image. Then, the captured image is delivered to the control unit 1 in an image-compressed form, and the control unit 1
Stores the image in the image compression memory 2 as data.

On the other hand, the control unit 1 has CG data generated and edited by an operation unit (not shown), or CG data received from another device by the image reception input unit 5.
Receives data and holds it internally. In the form as described above, the control unit 1 has the compressed natural image data and the CG data at the same time.

Next, a data flow when an image is recorded in the image processing apparatus having the above configuration will be described. The data in the image compression memory 2 in FIG. 1 is decoded by the data decompression unit 3 and written in the image memory unit 7 via the multiplexer MUX6. On the other hand, CG data is CG
It is expanded by the expansion unit 4 and written in the image memory unit 7 via the multiplexer MUX6. At the same time, the CG developing unit 4 stores in the bitmap memory unit 8 flags (“1”, “0”) indicating that the image is a CG image in association with each pixel position of the image. The CG image is "1" for the whole.
Flag may be stored as, or if the CG image is an image such as a character, the background portion thereof is set to “0”,
The flag may be stored so that only the character portion is set to "1".

In this way, on the image memory unit 7,
A natural image and a CG image are combined and created, and "1" and "0" flags corresponding to each pixel of the CG image are created in the bitmap memory unit 8. If these two types of images overlap, , The images positioned on the upper side are sequentially written in the image memory unit 7 later in sequence. When the natural image is superimposed on the CG image, the natural image is written in the image memory unit 7 and at the same time, the flag of the bitmap memory unit 8 corresponding to each pixel position is set by a signal line (not shown). It is cleared to "0".

As described above, as the image data, the data of the data expansion unit 3 and the CG expansion unit 4 are once expanded on the image memory unit 7, and then sequentially read by the address counter 9, and the image processing unit 10 is operated. The image processing unit 11 performs color processing. The image processing unit 10 performs color processing suitable for a natural image, and the image processing unit 11 performs color processing suitable for a CG image. The color processing results of these two image processing units are input to the selector 12.

On the other hand, the output of the bitmap memory unit 8 also
It is input as a selection control signal in the selector 12, and if it is a logic "1", it is determined to be a CG image, and the color processing result of the image processing unit 11 is selected. Further, in the case of “0”, it is determined that the image is a natural image, and the color processing result of the image processing unit 10 is selected. Then, the selection result output from the selector 12 is made into a real image by the image recording unit 13.

FIG. 2 is a detailed block diagram showing the configuration of the image processing units 10 and 11. Further, FIG. 3 is a detailed block diagram of the UCR calculation unit 23 which constitutes the image processing unit. In FIG. 2, a luminance signal R, which is input to the image processing unit,
G and B are logarithmically converted by the Log converter 21 for each color,
It is converted into C, M, and Y density signals. These C, M,
The Y signal is calculated by the primary matrix calculation unit 22 according to the following equation (1).

[0015]

[Equation 1]

C ', M', Y'obtained by the above calculation
The UCR calculator 23 performs undercolor removal and black generation, and as a result, four-color signals C ″, M ″, Y ″, and K ″ required by the recording apparatus are obtained. UCR shown in Figure 3
In the calculation unit, the C ', M', Y'signals are subtracted by the subtractor 2
5, 26, 27 and the minimum value calculation unit 24.
Of these, the minimum value calculation unit 24 compares the pixel data values of C ′, M ′, and Y ′, and the one having the smallest value, that is, Mi.
n (Y ′, M ′, C ′) is selected and input to the UCR amount calculation unit 28 and the smear amount calculation unit 29.

The smear amount calculation unit 29 has a function calculation or table as shown in FIG. 4A or 4B, and has a smear amount (black amount) K ″ optimal for the characteristics of the recording apparatus.
Is output. Similarly, the UCR amount calculation unit 28 is also shown in FIG.
It is a function calculation or table as shown in (A) or (B), and the UCR amount determined there is input to the subtracters 25, 26, 27. In addition, these UC
The function characteristics of the R calculation unit 28 and the smear amount calculation unit 29 do not necessarily have to be the same, and may be any function characteristics that select the optimum UCR amount or smear amount for the recording apparatus.

In the subtracters 25, 26 and 27, C ',
The UCR amount is subtracted from each color component of M ′ and Y ′, and C ″, M ″, and Y ″ to be given to the recording device are calculated. Comparing the image processing unit 11 and the image processing unit 10, the image processing unit 11
, The function is set so that both the UCR amount and the smear amount become large, suppressing the deterioration of black characters in CG images, and the quality of important black characters in Desk Top Publishing (electronic publishing, hereinafter referred to as DTP). While maintaining the above, the color processing of the color image is not adversely affected. In addition,
In an extreme setting, if R, G, and B are all close to 0, then U
The CR amount may be set close to 100% so that it is close to a single black color.

As described above, according to this embodiment,
By applying different color processing to the natural image and the CG image respectively, the C image can be processed without impairing the image quality of the natural image.
There is an effect that the image quality can be improved by increasing the UCR amount and the smear amount of black characters in the G image. In the above embodiment, the image memory unit 7 may not be provided, and the data expansion unit 3 and the CG expansion unit 4 may operate in real time in synchronization with the image recording unit 13. [Modification] Next, a modification of the above embodiment will be described. The circuit configuration of the image processing apparatus according to this modification is
Since it is the same as the image processing apparatus according to the above-described embodiment shown in FIG. 1, description thereof will be omitted here.

FIG. 5 is a block diagram showing a configuration example of the image processing unit 11 of the image processing apparatus according to this modification. The image processing unit shown in the figure performs color processing for CG images.
Depending on the application, too much gradation reproducibility may not be necessary. For example, the system according to the above embodiment is DT
When used as a P system, a CG image is mainly a character image, and it is not necessary to give importance to gradation. Further, it is not necessary to faithfully reproduce the change in gradation within the thin line, considering the redundancy of human eyes.

Therefore, in such a system, the image processing section 11 can be constructed with a simple circuit configuration as shown in FIG. The image processing unit (color processing circuit) shown in FIG. 5 has an area-sequential system or a dot-sequential system as its output data format, and outputs are sequentially switched and output by a color selection signal CSEL. Here, the three color luminance components R, G, B
Is 8 of R7 to R0, G7 to G0, B7 to B0, respectively.
Bit signals having a large subscript value, that is, R7, G7, and B7 correspond to MSBs, and R7 to R3.
G7 to G3 and B7 to B3 are always masking ROM 41
Has been entered in. The masking ROM 41 stores in advance the results calculated by the image processing unit having the configuration shown in FIG.

The selector 42 of FIG. 5 has an R2 as an input.
~ R0, G2-G0, B2-B0 are input, and the necessary one is selected according to the color required by the recording device,
It is output as L2-L0, which is the masking ROM4.
Input to 1. And in the masking ROM 41,
The output color is known by the selection signal CSEL, and the calculation accuracy is increased by the auxiliary bits L2 to L0.

To improve the calculation accuracy, a masking ROM
When 41 outputs C, M, and Y, it is necessary to increase the number of bits of R, G, and B, which are complementary colors, respectively. Therefore,
The selector 42 shown in FIG. 5 makes the selection shown in FIG. That is, CSEL is a 2-bit selection signal, and when it is 0, 1, 2, or 3, C, M, Y, K of the output device.
The outputs L2 to L0 correspond to L, which is a complementary color to C.
SB R2 to R0, complementary colors G2 to R0 for M and complementary colors B2 to B0 for Y are selected, and these are masking RO
It is input to M41.

For example, when CSEL = 3, that is, when the output device requests a black signal, R2, G2 and B2 are selected as L2 to L0. This is a masking RO
This is because the calculation accuracy does not change depending on the color when the minimum value is calculated in M41. When CSEL = 3, L2 to L0 may be set to R2, G2, and G1. This is because the achromatic signal component is mi
It is effective when weighting R, G, and B instead of n (Y, M, C) or Max (R, G, B).

That is, normally, the G component largely contributes to the brightness component, requires a large number of effective bits, and conversely, the B component does not significantly contribute to the brightness component.
This is because there is no point in increasing the number of effective bits.
As described above, by using the processing circuit shown in FIG. 2 as the image processing unit 10 constituting the image processing apparatus and the simple processing circuit shown in FIG. 5 as the image processing unit 11, the color processing circuit is obtained. Even if there are two, the circuit scale can be kept small.

That is, a color masking ROM is used in the color processing circuit for CG images, and a selector is provided in the preceding stage to select a lower bit of a required color for each output color, and to use it as a color masking ROM. By inputting, more accurate masking processing becomes possible, and at the same time, by using one ROM instead of using a masking ROM for each output color, it is possible to reduce the component mounting area and device volume on the circuit board. It is possible to reduce the cost, and it is possible to obtain advantages such as cost reduction and downsizing of the device.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0028]

As described above, according to the present invention,
By applying different color processing to the natural image and the CG image according to the state of the bitmap corresponding to the CG image, the UCR amount and the smear amount of the black character of the CG image can be determined without deteriorating the image quality of the natural image. There is an effect that the image quality can be improved by increasing the number.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a detailed block diagram showing the configurations of image processing units 10 and 11.

FIG. 3 is a detailed block diagram of a UCR calculation unit 23 which constitutes an image processing unit.

FIG. 4 is a diagram showing function characteristics that determine a smear amount and a UCR amount.

FIG. 5 is a block diagram illustrating a configuration example of an image processing unit 11 of an image processing device according to a modification.

FIG. 6 is a diagram showing selection by a selector according to a modification.

[Explanation of symbols]

 1 control section 2 image compression memory 3 data decompression section 4 CG decompression section 5 image reception input section 6 multiplexer 7 image memory section 8 bitmap memory section 9 address counter 10, 11 image processing section 12, 42 selector 13 image recording section 21 LOG Conversion unit 22 Primary matrix calculation unit 23 UCR calculation unit 24 Minimum value calculation unit 25, 26, 27 Subtractor 28 UCR amount calculation unit 29 Sumi amount calculation unit 41 Masking ROM

Claims (4)

[Claims] 1. An image processing device for developing a color natural image and a computer graphics image and outputting the same to an output device, and means for setting a flag in a bitmap memory corresponding to each pixel position forming the computer graphics image. A means for simultaneously performing a predetermined color process on both the developed color natural image and the image data of the computer graphics image, and a means for selecting the color-processed image according to the state of the flag. An image processing apparatus, comprising: the selected image output to an output device. 2. The masking circuit for color correction performs the color processing, and the masking circuit selectively supplies only necessary bits of each color component data. Image processing device. 3. The bit is a predetermined bit on the lower side of each color component data, the bit to be selected is changed for each color component requested by the output device, and the masking circuit is requested by the output device. The image processing apparatus according to claim 2, wherein a different table area is referred to for each color component. 4. An image processing method for expanding a color natural image and a computer graphics image and outputting them to an output device, wherein a flag is set in a bitmap memory corresponding to each pixel position forming the computer graphics image. And a step of simultaneously performing a predetermined color processing on both the developed image data of the color natural image and the computer graphics image, and a step of selecting the image after the color processing according to the state of the flag. An image processing method, comprising: outputting the selected image to an output device.