JP3325955B2 - Image processing device - Google Patents

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 for performing image processing using AD converted image data obtained by photoelectrically converting image information and reading.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus of this type, an image processing unit is provided with an attribute discriminating unit for discriminating image attributes (types of characters, photographs, halftone dots, etc.) for each pixel. In some cases, a density conversion curve is switched by a gamma conversion section based on data, and a spatial filter coefficient is switched by a spatial filter section (Japanese Patent Laid-Open No. 4-239269).
Reference).

In this technique, attribute data separated from image data from a processing circuit using attribute data is input to a processing circuit using the next attribute data with a delay by bypassing a processing circuit not using the attribute data. In addition, a delay circuit is provided for making the timing coincide with the input timing of the image data of the corresponding pixel to the processing circuit.

[0004]

However, in such a conventional attribute data transfer system, when a new process is inserted into the image processing unit, or when a change such as a change in the processing method or the order occurs, the process is not performed. There is a problem that the delay circuit also needs to be changed. In addition, since the transfer delay time of the attribute data must exactly match the image processing time of the bypassed processing circuit, reliability becomes a problem, and the processing required by the bypass processing circuit depends on the content of the image data. When the time changes, there are also problems such as unnecessary delay of the processing time, such as the need to delay the signal output in accordance with the longest processing time, and the necessity of complicated adjustments and expensive circuits. I was

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has improved the transfer method of attribute data of an image so as to cope with addition or change of an image processing method with a minimum change. It is an object of the present invention to provide an image processing apparatus which can be performed, has high reliability, and is advantageous in cost.

For this reason, the present invention is an image processing apparatus for performing image processing using image data for each pixel after AD conversion obtained by photoelectrically converting image information and reading the image information. An attribute discriminating unit for discriminating attributes, and a processing unit for performing a process using the attribute data of the image discriminated by the attribute discriminating unit; Includes a scaling unit that performs image enlargement / reduction processing before reaching the processing unit.
Image data that has been enlarged or reduced by the scaling unit.
The attribute data of the pixel having
Pixels that are closest in distance to the processed pixel
And the attribute data after the above processing
Attribute data adding means for outputting the attribute data to the next processing unit in association with the image data is provided.

[0007]

[0008]

The attribute discriminating unit discriminates image attributes, for example, a character area, a halftone image area, and a halftone image area, for each pixel, and the discriminated attribute data is appended to the image data by the attribute assigning means and is finally determined. The data is sequentially output to a processing unit that uses attribute data, and processing using the attribute data is performed as necessary.

With this configuration, even when a new process is inserted into the image processing unit or the processing method is changed, a circuit for delaying and outputting the determined attribute data is provided. No need to change. Also, zoom
The processing unit reduces and enlarges the image data and
The image data after processing is also reduced and enlarged by
Attribute data corresponding to the data
First, the attribute to be attached to the pixel having the processed image data
The data is calculated from the original pixel before processing closest in distance to the pixel.
By matching with the attribute data, the processed image data
Data and attribute data
As a result, it is possible to ensure the image quality as simple as possible.

In this case, the attribute data attached to the pixel having the processed image data is matched with the attribute data of the original pixel which is closest to the pixel in terms of distance, so that the processed image data and the attribute data are attributed. It is possible to make the correspondence with the data as good as possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The 8-bit image data of one pixel after AD conversion, which is obtained by photoelectrically converting and reading image information, is input to the attribute determination unit 1.

The attribute determining section 1 determines the attribute of an image for each pixel. Specifically, the image is a character area and a halftone image area
(Photo part) or halftone dot image area is determined, and the determined 2-bit attribute data (see Table 1 below) is output as a 10-bit signal attached to the 8-bit image data I do. The attribute data is sent to the gamma conversion unit 7 while being used together with the image data in an intermediate process.

[0013]

[Table 1]

If the method of discrimination is given, a window 3 × 3
When viewed in the area No., the character portion has a large change in luminance because it is binary, whereas the photograph portion has no large change in luminance because it is halftone. Utilizing this characteristic,
The maximum luminance Lmax and the minimum luminance Lmin of the × 3 area are detected, and (1) Lmax−Lmin <predetermined value (no luminance difference),
(2) Lmin <upper limit value (area is not all white), (3)
If all the conditions of Lmax> lower limit (area is not all black) are satisfied, it is determined that the image is a halftone image area (photograph).

The 10-bit output from the attribute discriminating unit 1 is input to the scaling unit 3 or the spatial filter unit 4 through the luminance / density converting unit 2. In the brightness / density conversion unit 2, conversion processing common to each area is performed without special use of the attribute data. However, while the attribute data is attached to the image data after the brightness / density conversion processing, the scaling processing unit 3 or the spatial filter Output to section 4.

The magnification processing section 3 performs reduction / enlargement (including the same magnification) in accordance with the magnification instruction. Specifically, as shown in FIG. 2, the processing is performed by, for example, linear interpolation. Referring to FIG. 2, if a and b are image data of original pixels A and B, and x is image data of pixel X after conversion, x = (1−P) × a +
P × b. On the other hand, simultaneously with the reduction / enlargement processing of the image data, the reduction / enlargement processing of the attribute data of the image is simultaneously performed.

As a method of reducing / enlarging the attribute data in this case, for example, an original pixel closest in distance to the pixel X converted by the linear interpolation, that is, an original pixel A based on the interpolation is used. , B, the attribute data of the original pixel A is added when P ≦ 0.5, and the attribute data of the original pixel B is attached to the image data x as the attribute data of the converted pixel X when P> 0.5, and is sent to the subsequent processing unit. Output (see FIG. 3).

The spatial filter unit 4 converts the spatial frequency characteristics of the image information, and includes frequency characteristic switching means therein, and performs edge enhancement based on attribute data input along with the image data. Alternatively, smoothing is performed. However, there may be no conversion (through). Specifically, edge enhancement is performed for a character area, and smoothing is performed for a halftone image area. In the case of a halftone dot image area, through processing is performed at the time of reduction / enlargement, and smoothing is performed at the same magnification.

Here, selectors 5 and 6 as switching means
These selectors 5 and 6 are switched between reduction and enlargement in accordance with a magnification change command. At the time of reduction, the selectors 5 and 6 are switched to the illustrated side a, and the scaling unit 3 comes before the spatial filter unit 4. That is, after being reduced by the scaling unit 3, it passes through the spatial filter unit 4. This prevents the occurrence of a moiré-like pattern at the time of edge enhancement in the spatial filter unit 4.

The switching of characteristics in the spatial filter unit 4 in accordance with the attribute data is performed in accordance with the attribute data that has been reduced and enlarged simultaneously with the image data in the scaling unit 3. The processed image is processed with characteristics suitable for the obtained image, and good image quality can be secured. At the time of enlargement, the selectors 5 and 6 are switched to the side b in the figure, and the spatial filter
After the spatial filter processing is performed in accordance with the attribute information determined by the attribute determination unit 1, the data is sent to the scaling unit 3 and enlarged. As a result, the effect of edge enhancement or smoothing in the spatial filter unit 4 does not decrease.

In the case of the same magnification, the selectors 5 and 6 are provided with a,
b, but the scaling unit 3 passes the pixel data and the attribute data as they are without performing reduction / enlargement processing (formally, P = 0 in the scaling equation, and formally performs scaling processing). When passing through the spatial filter unit 4, edge enhancement and smoothing are performed in the character area and the halftone image area according to the attribute data in the same manner as at the time of reduction / enlargement. Smoothing is also performed in the point area.

The image data after the image processing that has passed through the scaling unit 3 and the spatial filter unit 4 is output to an output device (not shown) via a gamma conversion unit 7 and is subjected to laser recording or filing to an image memory. You. The gamma conversion unit 7 also performs processing by switching conversion characteristics according to the attribute data. When the characteristics are not simply switched according to the attribute data in the gamma conversion unit 7, the output of the attribute data to the gamma conversion unit 7 is unnecessary.

As described above, in each processing section up to the gamma conversion section 7, attribute data is added to image data for each pixel and passed therethrough, and used for processing as necessary. Even if the order of the image processing is switched according to the reduction or enlargement, the processing method is changed and the processing time is changed, or a new processing is inserted, Since attribute data is moved, unlike the conventional method of transferring attribute data separated from image data with delay, there is no circuit change such as a change in delay time, high reliability, and high cost. This is also advantageous.

[0024]

As described above, according to the present invention, the attribute data is attached to the image data and transferred to the final processing unit for performing image processing using the attribute data of the image. Even if there is a change in the processing method and order of image processing, addition of new processing, etc., attribute data can be reliably transferred integrally with image data without requiring any special circuit change, resulting in excellent reliability. It is also advantageous in terms of cost.

Further, the scaling of the image data by the scaling unit is performed.
By performing the scaling process on the attribute data at the same time as the processing, attribute data suitable for the scaled image can be attached . In particular, as the scaling process of the attribute data, the attribute of the scaled pixel is used. data by matching the attribute data of the nearest original pixel in the converted pixel, a simple method, and to increase the accuracy of the attribute data as much as possible
Process based on the attribute data,
Image quality can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a method of scaling the image data.

FIG. 3 is a diagram showing a scaling method of attribute data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Attribute discrimination part 2 Brightness density conversion part 3 Magnification processing part 4 Magnification processing part 7 Gamma conversion part

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H04N 1/40 101D (56) References JP-A-63-191475 (JP, A) JP-A-5-298440 (JP, A) JP-A Heisei 3-169167 (JP, A) JP-A-63-54064 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/40 G06T 3/40 G06T 5/00 100 H04N 1 / 393 H04N 1/409

Claims (1)

(57) [Claims] An image processing apparatus for performing image processing using image data for each pixel after AD conversion obtained by photoelectrically converting image information and reading the image information, wherein an image processing unit determines an attribute of an image for each pixel. An attribute discriminating unit, and a processing unit that performs processing using the attribute data of the image determined by the attribute discriminating unit, from the attribute discriminating unit to a final stage processing unit that uses the attribute data of the image In the meantime, enlarge or reduce the image
The image data that has been scaled up and down by the scaling unit.
The attribute data of the pixel to be processed
Of the pixels that are closest in distance to the processed pixel
The attribute data with the image after the processing.
An image processing apparatus comprising an attribute data assigning means for outputting the attribute data to a next processing unit in association with data .