JPH047679A - Picture reducing device - Google Patents

Abstract

PURPOSE:To obtain a reduced picture with less disturbance as against the white/ black distribution of an original picture by providing a parameter operation means and a picture element data decision means deciding picture element data of the reduced picture from a density parameter. CONSTITUTION:Picture element data of the original picture is first inputted to a main scan direction density parameter operation circuit 1 in the order of the direction of main scanning. An operation is executed for respective lines in respective directions of main scanning and the density parameter is obtained. Then, the obtained density parameter is stored in a primary density parameter memory 2. In such a case, the density parameter operation circuit 1 operates and obtains the density parameter of the reduced picture element from the corresponding rate of the picture elements in the original picture corresponding to the reduced picture elements, to the reduced picture elements. The picture element data discrimination circuit 4 decides picture element data or respective picture elements in the reduced picture from the obtained density parameter. Thus, a reduction processing with less disturbance can be executed compared to the density distribution of the original picture as against a regular binary picture and a pseudo halftone picture by a dither method.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an image reduction device for reducing an image represented by digital information.

(B) Conventional technology Conventionally, devices that handle images represented by digital information, such as facsimile machines, word processors, and image processing devices that edit images, reduce images of a certain size to an appropriate size. Reduction processing is performed frequently.

Normally, reduction processing is performed by appropriately thinning out pixels in the original image according to the reduction ratio, or by taking a logical sum between a plurality of adjacent pixels according to the reduction ratio.

Images obtained by reducing the original image shown in FIG. 4A at a reduction rate of 3/10 are shown in FIGS. 4B and 4C.

In Figure 4B, the reduction process was performed by thinning processing, and lines other than the marked lines are thinned out (the lines to be thinned out are determined by an appropriate algorithm according to the size of the original image and the reduction rate. ), the reduced image will have many so-called "missing parts".

In addition, Figure 4C shows the reduction process performed by logical sum operation, and by using an appropriate algorithm, the logical sum of the adjacent 166 pixels, 12 pixels, or 9 pixels shown in Figure 4A is performed, and the reduction process is performed. Although there is no "dropout" in the image, so-called "collapse" has occurred.

Furthermore, there is a dither method that expresses the density (gradation) of an image using the distribution of black and white pixels as a method of pseudo-representing intermediate gradations using black and white binary values, but when an image expressed using the dither method is reduced When an image is reduced by the above-mentioned thinning process, the density distribution is disturbed and the image quality is significantly deteriorated.

Therefore, a dedicated reduction device for dithered images has been proposed, for example, as in Japanese Patent Application Laid-Open No. 164369/1983, which estimates the density of the original image (pixel) from the dithered image and performs reduction processing on the estimated image. has been done.

(c) Problems to be Solved by the Invention When image information is reduced as described above, pixel data may be missing or distorted, and the distribution of black and white pixels may be significantly disordered compared to the original image. Requires reduction processing.

The present invention has been made in view of the above, and provides a reduction device that reduces an original image into an image with less disturbance in the distribution of black and white pixels of the original image through simple processing. be.

(d) Means for Solving the Problems The present invention is an image reduction device that reduces an original image represented by digital information, and the ratio of the pixels of the original image to the pixels after reduction is determined from the ratio of the pixels of the original image to the pixels after reduction. and pixel data determining means for determining pixel data of a reduced image from the density parameters calculated by the parameter calculating means.

(E) The effect parameter calculating means calculates the density parameter of the reduced pixel from the ratio of each pixel of the original image corresponding to the reduced pixel to the reduced pixel, and the pixel data determining means calculates the density parameter of the reduced pixel. Since the pixel data of the reduced pixel is determined by the parameters, it is possible to obtain a reduced image with less disturbance to the black and white distribution of the original image.

(f) Embodiment FIG. 1 is a schematic diagram of an embodiment of the image reduction apparatus of the present invention.

In (1), the pixel data of the original image is input in the order of the main scanning direction, and according to the reduction rate instructed by the control means (not shown).
A main scanning direction density parameter calculation circuit which calculates a density parameter according to the proportion of each pixel of the original image corresponding to a pixel after reduction, and reduces the original image in the main scanning direction; (2) is the density parameter calculation circuit in the main scanning direction; This is a primary concentration parameter memory that stores the concentration parameters obtained by the parameter calculation circuit (1).

In (3), the density parameters calculated by the main scanning direction density parameter calculation circuit (1) and stored in the primary density parameter memory (2) are inputted in the order of the sub-scanning direction (Y direction), and the density parameters are input from the control means (not shown). According to the indicated reduction rate,
This sub-scanning direction density parameter calculation circuit calculates a density parameter according to the proportion of each pixel of the original image corresponding to the pixel after reduction, and reduces the original image in the sub-scanning direction.

(4) is calculated by the main-scanning direction density parameter calculation circuit (1) and the sub-scanning direction density parameter calculation circuit (3), and is based on the reduced image density parameter that has been reduced in the main-scanning direction and the sub-scanning direction. This is a pixel data determination circuit as a pixel data determining means for determining pixel data of each pixel.

Now, the original image shown in Figure 2A (the same image as Figure 4A) is
Consider the case of reducing the size to 710.

When considering one line in the main scanning direction, the ratio that one pixel of the original image corresponds to one pixel of the reduced image is 3/10 of the reduction rate.
It is. The correspondence relationship between each pixel of the original image and each pixel of the reduced image is as shown in FIG. (Sl, S2, S3) are each 3/10, 4 from the left
The th pixel (S4) corresponds to 1/10.

The density parameter of pixel D1 is calculated as follows from the ratio of pixels of the original image to pixels of the reduced image.

DI=[S1]X 3/10+[S2]X 3/10+
[53] X 3/10 + [S4] Desired.

D2=[S4]X 2/10+[S5]X 3/10+
[S6]x 3/10+[S7]X 2/10D3=(
S7)X 1/10+[S8]X 3/10+ (S
91x 3/10+[S 10]x 3/10
In addition, in these formulas, (Sl), (S2), etc., enclosed in parentheses indicate the pixel data of each pixel, and if the pixel is black, 1 is applied, and if it is white, 0 is applied. .

The pixel data of the original image is first input to the main scanning direction density parameter calculation circuit (1) in the order of the main scanning direction, and the main scanning direction density parameter calculation circuit (1) performs the above-mentioned processing for each line in the main scanning direction. Perform calculations to obtain concentration parameters,
The obtained concentration parameters are stored in the primary concentration parameter memory (2)
to be memorized. FIG. 2B shows the density parameters calculated by the main scanning direction density parameter calculation circuit (1) for the original image shown in FIG. 2A. The original image is reduced in the main scanning direction by calculating the density parameters in the main scanning direction density parameter calculation circuit (1).

When the density parameter calculation circuit (1) finishes calculating the density parameters, the density parameters stored in the -th density parameter memory (2) are transferred to the sub-scanning direction density parameter calculation circuit (3) in the order of the sub-scanning direction. Enter. In the sub-scanning direction density parameter calculation circuit (3),
Similarly to the main scanning direction density parameter calculation circuit (1),
Calculations similar to those described above are performed depending on the ratio of pixels in the original image to pixels in the reduced image. FIG. 2C shows the density parameters obtained by the sub-scanning direction density parameter calculation circuit (3) from the density parameters shown in FIG. 2B stored in the -th order density parameter memory (2). The original image is reduced in the sub-scanning direction by calculating the density parameters in the sub-scanning direction density parameter calculation circuit (3).

In this way, the original image is reduced in the main scanning direction and the sub-scanning direction, and each density parameter obtained from the sub-scanning direction density parameter calculation circuit (3) is sequentially processed by the pixel data determination circuit (
4) and set an appropriate threshold (here, 1/2)
The pixel data (black or black) of each pixel is determined from the density parameter based on .

As a result, as shown in the second diagram, a reduced image obtained by reducing the original image (FIG. 2 A) to 3710 pixels is obtained.

Figures 4B and 4C are the same original images reduced using the conventional method.
It can be seen that the image is reduced relatively faithfully to the original image, with fewer omissions and collapses.

In this embodiment, the pixel data of the reduced image is determined after calculating the density parameters in both the main scanning direction and the sub-scanning direction. Determine the pixel data of the image that has been reduced in the sub-scanning direction, calculate the density parameter in the sub-scanning direction from the determined pixel data, perform the reduction in the sub-scanning direction, and then create the reduced image from the density parameter that has also been reduced in the sub-scanning direction. pixel data may be determined.

In addition, the determination of pixel data by the pixel data determination circuit is
Instead of using a fixed threshold value, the obtained density parameter may be regarded as the estimated density, and the pixel data may be determined using an appropriate dither matrix corresponding to the estimated density.

(g) Effects of the Invention As is clear from the above description, the present invention provides a density parameter calculation circuit in which each pixel of the original image corresponding to the pixel after reduction is calculated from the ratio corresponding to the pixel after reduction. The pixel data of each pixel in the reduced image is determined by the pixel data judgment circuit from the obtained density parameter, so it is not possible to create a normal binary image or a pseudo halftone image using the dither method. On the other hand, reduction processing can be performed with less disturbance than the density distribution of the original image. Further, when determining the value of pixel data, it is also possible to adjust the density of the reduced image by changing the threshold value.

Further, the reduction processing device of the present invention performs reduction processing on a pixel-by-pixel basis and can perform reduction processing on image information consisting of pixel data that is continuous in the scanning direction, so it can be applied to image processing devices such as facsimile machines. .

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the image reduction device of the present invention;
FIG. 2 is an explanatory diagram of the operation of an embodiment of the apparatus of the present invention, FIG. 3 is an explanatory diagram of the reduction operation according to the present invention, and FIG. 4 is an explanatory diagram of the conventional reduction processing. (1)...Main scanning direction density parameter calculation circuit (parameter calculation means), (2)...-next density parameter memory, (3)...Sub-scanning direction density parameter calculation circuit (parameter calculation means), (4) Pixel data determination circuit (pixel data determination means).

Claims (1)

[Claims] (1) In an image reduction device that reduces an original image represented by digital information, a parameter calculation means calculates a density parameter of a reduced pixel from a ratio of pixels of the original image corresponding to a reduced pixel, and the parameter An image reduction device comprising: pixel data determining means for determining pixel data of a reduced image from density parameters calculated by the calculating means.