JPH0614350B2 - Image processing device - Google Patents

Description

The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus having a function of scaling input image information.

[Prior Art] As a conventional apparatus of this type, there is, for example, a copying machine, in which a document image is digitally read by a solid-state image sensor such as a linear image scanner (CCD), and the read image is enlarged or reduced. Some have a scaling function. As a general variable magnification method in these devices, the magnification in the feeding direction is changed by changing the scanning speed in the sub-scanning direction (moving direction of feeding the CCD). Further, the magnification in the main scanning direction is changed by storing or thinning out pixels in the main scanning direction (direction orthogonal to the feeding direction).

For example, when performing three times the enlargement processing, the sub-scanning direction movement speed of the time constant times the V _1, a moving speed in the sub-scanning direction and V _1/3, also, the main scanning direction, 1 pixel The image data of 3 times enlargement processing is formed by repeatedly outputting the image data of 3 times.

[Problems to be Solved by the Invention] However, if the scaling processing is performed only by such a method,
As shown in the figure, since the enlarged output image has the same data in units of 3 pixels, it is preferable for characters or symbols having a single density, but for example, a halftone image with a smooth density change such as a photograph is obtained. On the other hand, the scaling processing is not preferable in terms of image smoothness.

The present invention has been made to improve the above-mentioned problems of the prior art, and in the scaling processing for input image information having both single density information and halftone information, the intermediate image in the input image information is processed. An object of the present invention is to provide an image processing device that smoothes and processes the density change in the scaling process for the key information.

[Means for Solving Problems] In order to solve this problem, the image processing apparatus of the present invention has the following configuration. That is, in an image processing apparatus for scaling an input image to form output image information, an input unit for inputting image information, and an image represented by the image information based on the image information input by the input unit. Is a halftone image, a scaling unit that performs scaling processing on the image information input by the input unit, and the input unit based on the determination result by the determination unit. And a smoothing unit that performs a smoothing process on the image information scaled by the scaling unit when the image represented by the image information input by is a halftone image.

[Operation] In the configuration of the present invention, the determination unit determines whether the image represented by the image information input by the input unit is a halftone image. As a result of this determination, when it is determined that the image is a halftone image, the smoothing unit smoothes the image information scaled by the scaling unit.

Embodiments Embodiments according to the present invention will be described in detail below with reference to the accompanying drawings.

As an image reading method, for example, a large number (for example, 128) of picture elements in a solid-state image sensor such as a linear image scanner (CCD) are arranged in the sub-scanning direction, and image data in the image sensor is sub-scanned. It may be possible to read digitally by sending in the scanning direction. CCD width is 8
In the case of mm, the image is read with a width of 8 mm for each scan. That is, in FIG. 7, the image is read from (a) to (b) with a width of 8 mm, then the image data is read from (b) to (c), and then the image data is read in the same manner from (c) to (d). As an image forming mechanism, for example, a multi-bubble jet head (head portion) having 128 nozzles in a width of 8 mm is scanned from 8 to 8 in width from (e) to (f) as shown in FIG. To form. Then (f)
Return to (g). After that, the image is similarly formed by 8 mm.

The image processing apparatus of this embodiment will be described with reference to FIG. 1 in view of the above-described image input and output mechanism.

The image signal read by the image reading unit 31 and converted into digital density data passes through the primary differentiating unit 32, and the density change rate (primary differential value D) near the target pixel is calculated from the pixel data before and after the target pixel data. Calculate from the formula.

D = {| (a + b)-(d + e) |} / 2 equation 1 where D: primary differential value of target pixel, a: 2 of target pixel
Pixel data after the pixel, b: pixel data one pixel after the target pixel, d: pixel data one pixel before the target pixel, and e: pixel data two pixels before the target pixel.

Further, when this first-order differential value D is a predetermined value or more, it is "1", and when it is less than that value, it is "0".
A signal of "1" (hereinafter, this signal is referred to as a density change signal) is output to the scaling unit 33 described later.

Equation 1 calculates the density change of the pixels on both sides including the pixel of interest, and the greater the change, the larger D becomes. Therefore, when the primary differential value D is equal to or larger than the predetermined value, it is determined that the input image has a character or a symbol that is single density information,
If it is less than the predetermined value, it is determined that the information is halftone image information such as a photograph.

The pixel data read by the image reading unit 31 and the density change signal from the primary differentiating unit 32 are both included in the scaling unit 3.
Input to 3.

Further, the pixel data input to the scaling unit 33 is controlled by the control unit 3 according to the designated magnification by an operation switch (not shown) or the like.
Magnification according to the instruction from 4, and the magnification RA in the magnification unit 33
It is temporarily stored in M33a.

Next, the image data read from the scaling RAM 33a is
The density change signal is input to the smoothing unit 35, and the density change signal is input to the control unit 34. In the control unit 34, the control unit 34 outputs a select signal to the smoothing unit 35 and the selector 36 under the conditions shown in Table 1.

In the selector 36, the smoothing unit 35
The smoothed image data and the image data from the scaling unit 33 are input to the selector 36, and the control unit 34 outputs the 2
You will have to choose one of the two.

In this way, depending on the select signal, the scaling unit 33 or the smoothing unit 3
5 is selected as the output image, and the selected image data is output from the selector 36.

Further, the image data selected by the selector 36 is processed by the image processing unit 37, converted into dot data, and then output to the printer unit 38 to form an output image in the printer unit.

Next, the operation of the primary differentiator 32 will be described with reference to FIG. In the primary differentiator 32, the previously extended formula 1 is obtained.

The pixel data converted into the density data output from the image reading unit 31 is delayed by one pixel by the video clock φ in the latch unit 41 and then input to the adder 42. In the adder 42, the pixel data and the pixel data delayed by one pixel are input and added. The output from the adder 42 is input to the latch unit 43 and the inverter 45.
The latch unit 43 and the latch unit 44 are delayed by one pixel by the video clock φ and are input to the adder 46 later. Further, the data input to the inverter 45 is inverted and becomes a one's complement and is output to the adder 46. Adder 4
In 6, the output data of the adder 42 and the latch 4 are added by adding "1" to the input data from the inverter 45, and making the 1's complement the 2's complement and adding it to the output of the latch 44.
4 is subtracted from the output data. Next adder 4
The output of 6 is input to the table ROM 47 as an address. The table ROM 47 is pre-stored so that the output data becomes 1/2 of the input address.
In this way, it is halved by the table ROM 47 and is output as temporary differential data. Further, the primary differential data input to the comparator 48 is compared with a predetermined set value, and if the primary differential value is larger than the set value, it is set to "1", and if it is smaller, it is set to "0", and the result is changed in density. It is output as a signal. The set value set in the comparator 48 can be arbitrarily set according to an instruction from the outside.

Next, the processing of the variable power unit 33 will be described with reference to FIG.

Here, in the scaling processing in the sub-scanning direction, the sub-scanning speed V1 of the printer of the reading unit is kept constant and the speed of the reader is set to V ₁ /
The description will be omitted as it is performed by changing to n (n: scaling factor).

For the scaling processing in the main scanning direction, a scaling mode signal is input to the memory control unit from a control circuit (not shown).
The memory control section includes an address clock generator 12 and a write pulse generator 13, and a variable magnification buffer memory 11
Address counter 1 when writing to -1, 11-b
The number of clock pulses 4-a and 14-b is determined, and the write pulse of the variable scale buffer memory is generated.
This is achieved by increasing or decreasing the number of clock pulses and the write pulse according to the scaling factor. In this variable power buffer memory, writing and reading are alternately performed by the variable power buffer memories 11-a and 11-b. For example, at the time of n-fold enlargement, the data of the same pixel is written to n addresses in 11-b in the write mode (w) of the variable-size buffer memories 11-a and 11-b. In addition, at the time of 1 / n reduction, one pixel out of n pixels is written to one address, and when the read mode is entered, if the address is stepped up by the video clock φ, the pixel data is interpolated. , Thinning will be achieved.

Further, although the motor speed on the image reading side is changed in this embodiment, the motor speed on the recording side may be changed.

Next, the processing operation of the smoothing unit 35 will be described with reference to FIG.

The smoothing unit 35 includes a matrix corresponding to the scaling factor, for example, 1 × for 2 × enlargement and 1 × for 3 × enlargement.
It has a primary matrix of three. In this matrix, the following formula is calculated.

That is, in the case of 2 times enlargement, D = 1/2 (a + b): 1 × 2 In the case of 3 times enlargement, D = 1/3 (a + b + c): 1 × 3 where D is the image output data of the pixel of interest and b Is the image input data of the target pixel, a is the image input data one pixel after the target pixel data, and c is the image input data one pixel before the target pixel data.

The size of this matrix is switched according to the enlargement ratio. In this embodiment, only 1 × 2 and 1 × 3 matrices are used, but 1 × n (n
There is no problem even if a matrix size of (double magnification) is used.

Now, the smoothing unit 35 performs the smoothing process as follows.

[In the case of equal size] The output image data of the variable magnification buffer is delayed by one pixel by the latch 29 and goes to the selector 27. Selector 27
Selects and outputs the same size image data according to a selection signal from the control unit 23.

[In the Case of Double Enlargement] The enlarged image data is delayed by one pixel by the latch 21. The delayed image data is added by the adder 24 to the input enlarged image data. The added data is output to the table ROM 28 as an address, and 1
The data averaged to / 2 is output to the selector 27.
The table ROM 28 has a structure in which the input and output correspond to each other 1: 1. The selector 27, in response to the selection signal from the control unit 23 as described above, outputs the table R
The output data of the OM 28 is selected and output.

[In case of 3 times enlargement] The data delayed by the latch 21 is delayed by another pixel by the latch 22. Output of latch 22 and adder 2
The outputs of 4 are added by the adder 25, and the result is entered into the table ROM 26. After averaging to 1/3 in the table ROM 26, it enters the selector 27. The selector 27 selects and outputs the output of the table ROM 26 according to the selection signal from the control unit 23.

In this way, processing is performed corresponding to each magnification.

FIG. 5 shows an output image when the smoothing unit 35 smoothes the image data which has been magnified 3 times by the magnification varying unit 33, for example, as in the conventional enlarging process (FIG. 6). As is clear from the output image in which three target pixel data are output side by side (in the case of 3 times enlargement), it is possible to process the output image after the enlargement processing with the density steps smoothed.

The smoothing process as described above is performed when the density change signal from the first-order differentiating unit 32 is “0”, that is, the first-order differentiating value D of one equation.
Is less than or equal to a predetermined value and it is determined that the input image is a halftone image, the control unit 34 outputs a select signal to that effect to the selector 36 so that the image data from the smoothing unit 35 is processed by the image processing unit 37. Will be output to.

Further, when the primary differential value D is equal to or larger than the predetermined value, the density change signal to the control unit 34 becomes “1”, and the control unit 34 outputs a select signal to that effect to the selector 36 so that the scaling unit 33 outputs. The image data of is output to the image processing unit 37.

As described above, according to the present embodiment, when the input image information is scaled and output, halftone image information is detected in the input image. The discontinuity of the density change of only the image information can be smoothed by the small-scale circuit configuration.

Further, in the present embodiment, the description has been given only to the case where the variable magnification is 1 ×, 2 ×, and 3 ×, but it goes without saying that other magnifications can be applied.

Further, it is obvious that the image reading device and the output device for forming the output image are not limited, and for example, the output device may be a laser beam printer or the like.

Furthermore, the present invention can be applied to smoothing image data that has been subjected to conventional scaling processing.

As described above, according to the present invention, it is determined based on the input image information whether the image information is a halftone image,
Smoothing processing is performed on halftone images that have undergone scaling processing based on the results of that determination, so halftone images can be played back smoothly without degrading characters, line drawings, etc. during scaling. You can

[Brief description of drawings]

FIG. 1 is an overall block diagram of the image processing apparatus according to the present embodiment, FIG. 2 is a block diagram of a first-order differentiation unit, FIG. 3 is a block diagram of a variable power unit, and FIG. 4 is a block diagram of a smoothing unit. FIG. 5 is a diagram showing an example of the enlarging process of this embodiment, FIG. 6 is a diagram showing a conventional enlarging process, FIG. 7 is a diagram showing the operation of the image reading process, and FIG. 8 is forming an output image. It is a figure which shows the processing operation at this time. In the figure, 11-a, 11-b ... Variable RAM buffer RAM, 1
2 ... Address clock generator, 13 ... Write pulse generator, 14-a, 14-b ... Counter, 21, 21
2,29 ... Latch, 24,25 ... Adder, 26,2
8 ... Table ROM, 23 ... Smoothing control unit, 27 ...
... selector, 31 ... image reading section, 32 ... primary differentiation section, 33 ... variable magnification section, 34 ... control section, 35 ... smoothing section, 36 ... selector, 37 ... image processing section, 38 ... …
Printer unit, 41, 43, 44 ... Latch, 42, 46
...... Adder, 45 …… Inverter, 47 …… Table R
OM, 48 ... A comparator.

Claims (1)

[Claims] 1. An image processing apparatus for performing scaling processing on an input image to form output image information, and input means for inputting the image information, and displaying the image information based on the image information input by the input means. Determination means for determining whether or not the image to be formed is a halftone image, scaling means for performing scaling processing on the image information input by the input means, and based on the determination result by the determination means, Smoothing means for performing smoothing processing on the image information scaled by the scaling means when the image represented by the image information input by the inputting means is a halftone image. A characteristic image processing device.