JP3288748B2 - Image processing method - 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 method , for example, an image processing method having a communication function.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus such as a facsimile, a Laplacian filter as shown in FIG. By doing so, processing has been performed to enhance the edges of the image.

[0003]

However, in the edge emphasizing processing as in the above-mentioned conventional example, the degree of emphasis becomes higher in a region having a higher spatial frequency. When reading, the noise component on the document is emphasized, and there is a disadvantage that the image becomes noisy.

If edge enhancement is not performed or the degree of enhancement is suppressed in order to suppress the emphasis on noise components, there are disadvantages that the edges of characters and figures are blurred and the reproducibility of thin lines is deteriorated. Was.

The present invention has been made in view of the above-described drawbacks of the conventional example, and has as its object to provide an image processing method capable of suppressing image noise and improving image quality. The point is to provide.

[0006]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, the image processing method according to the present invention, when high- quality paper is specified as a medium of a document to be read, performs processing for enhancing the edge amount of image data obtained by reading the document, When recycled paper is specified as the medium of the original to be read, the edge amount is increased based on the edge amount of the image data obtained by reading the original.
It is determined whether or not to perform the adjusting process .

[0007]

With this configuration, when high- quality paper is designated as a medium of a document to be read, a process of emphasizing the edge amount of image data obtained by reading the document is performed. Also, when recycled paper is specified as the medium of the original to be read, the edge amount is determined based on the edge amount of the image data obtained by reading the original.
It is determined whether or not to execute the emphasizing process .

[0008]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. <First Embodiment> FIG. 1 is a block diagram according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a line buffer for accumulating image data for a plurality of lines, 2 a register for accumulating a pattern of a pixel matrix, 3 an edge emphasizing circuit for performing an edge emphasizing process on a pixel of interest, and 4 a device of the present apparatus. An operation unit 5, a binarization circuit for binarizing multi-valued image data output from the edge enhancement processing circuit 3, a document reading unit 6, a CPU 7 for controlling the entire apparatus, and a CPU 8
The ROM 7 stores programs for operating the RAM 7, and the RAM 9 is used as a work area for various programs.

The operation unit 4 has a key for designating a mode corresponding to the recycled paper according to the present embodiment, that is, a recycled paper mode.

Next, the operation according to this configuration will be described.

The image data read by the document reading section 6 is subjected to shading correction, ABC processing, and the like.
After being D-converted and converted into a digital signal, it is serially transferred on a pixel-by-pixel basis and input to the line buffer unit 1. The register unit 2 forms a pixel matrix from the output of the line buffer unit 1. Here, ABC (Auto
Background Control is based on a white background (such as a white reference plate of a scanner unit) when there is a uniform density on the background of the original (for example, when characters are written on a blue original). When a document is read and image processing (binarization) is performed, noise appears in the background portion, and the reproducibility of characters deteriorates. Therefore, depending on the background density of the original, 2
This is a process of changing the threshold value of the binarization or changing the reference voltage of the A / D converter.

FIG. 3 is a block diagram showing the internal configuration of the line buffer unit 1 and the register unit 2 according to the first embodiment. In this embodiment, the line buffer unit and the register unit 2 constitute a 3 × 3 pixel matrix.

In FIG. 3, reference numerals 201 and 202 denote line buffers (LB) capable of storing one line of image data;
Reference numerals 201 to 209 denote register matrices (R) for storing 3 × 3 pixel matrix patterns.

The edge enhancement processing circuit 3 calculates the edge amount of the pixel of interest from the output of the register unit 2 and performs edge enhancement by adding the edge amount to the pixel of interest. For example, in the case of the Laplacian filter shown in FIG. 2, the edge amount EG can be expressed by the following equation (1). That is, EG = 4X−
(A + B + C + D) (1) where X indicates target pixel data, and A, B, C, and D indicate peripheral pixel data.

Edge enhancement is performed by multiplying the edge amount EG calculated by the above equation (1) by an appropriate coefficient and adding the result to the pixel data of interest.

FIG. 6 is a block diagram showing the internal configuration of the edge enhancement processing circuit 3 according to the first embodiment. In the figure, 3-1 is an arithmetic circuit for calculating a target pixel edge amount, 3-2 is a sign determination circuit for the edge amount, 3-3 is a multiplier for multiplying the edge amount by a constant, and 3-4 is an arithmetic circuit. An adder for adding the output of 3-3 and the value of the pixel of interest;
-2 is a selector that selects and outputs one of image data on which edge enhancement has been performed and image data on which edge enhancement has not been performed based on the output of -2 and the control signal from the operation unit 4. FIG. 4 is a diagram showing an example of a pattern of recycled paper according to the first embodiment in the case of a 3 × 3 pixel matrix. The numerical values in FIG. 4 indicate the density of each pixel data.

When edge enhancement is performed according to FIG.
When the edge amount EG is multiplied by 、, that is, when the coefficient is １ ／ and added to the target pixel (the density value is 15), the value of the target pixel is 15 + EG / 2 = 15 + (4 × 15− (7 + 7 + 7 + 7)) / 2 = 31. If the threshold is 30 and binarized, 3
Since 1> 30, it becomes black and appears as noise. On the other hand, the “recycled paper mode” is selected by the operation unit 4, and the selector 3-5
In the above, if the edge amount EG is positive, it is set to output data without edge enhancement, and if the edge amount EG is negative, it is set to output the edge-enhanced value. Also in the pattern example of FIG. 4, control can be performed so that even if binarization is performed, the pattern becomes white and does not appear as noise.

The above procedure is shown in the flowchart of FIG. The processing procedure described below is controlled by the CPU 7, and each processing is executed by each circuit shown in FIG.

In steps S51 and S52, the image data read by the document reading section 6 is processed by the edge amount calculating circuit 3.
The edge amount is calculated at -1. If it is determined in step S53 that the original is high quality paper by the operation unit 4, the sign determination is not performed, and the edge enhancement is performed by adding the edge amount to the target pixel in step S55.

On the other hand, in step S53, the operation unit 4
In step S54, it is determined in step S54 whether the edge amount is positive or negative by the sign determination circuit 3-2. If negative, the edge amount is added to the pixel of interest in step S55 as in the case of the high-quality paper document, and edge emphasis is performed. If the value is positive, the pixel data of interest is output as it is without adding the edge amount, and the binarization circuit 5 performs binarization processing in step S56.

As described above, according to the first embodiment, when the read original is a recycled paper original, the degree of edge enhancement is changed by the sign of the correction amount for edge enhancement. This makes it possible to obtain a clear image with little noise in the case of a recycled paper original. <Second Embodiment> In the second embodiment as well, a method for suppressing noise generation according to the recycled paper mode will be described.

FIG. 7 is a block diagram showing the internal configuration of the edge emphasis processing circuit according to the second embodiment. In the figure, components corresponding to those in FIG. 1 are represented by adding the dashes (') to the same reference numerals.

In the edge enhancement processing circuit 3 ', 3
Reference numeral -6 denotes a second multiplier for multiplying the edge amount of the target pixel by a coefficient different from that of the multiplier 3-3.

According to the pattern example of FIG. 4 described above, when the edge amount EG is multiplied by 1/4 and added to the target pixel, the value of the target pixel after edge enhancement is 15 + EG / 4 = 15 + (4 × 15). − (7 + 7 + 7 + 7)) / 4 = 23. Even if the binarization process is performed with the threshold set to 30,
From the relationship of 23 <30, control can be performed so that the color becomes white and does not appear as noise.

[0025] If the "recycled-paper mode" key on the operation unit 4 'is pressed, the selector 3-5, when the edge amount is positive, smaller coefficients of multipliers 3-3,3- 6 In other cases, if the data with the larger coefficient is selected and output, it is possible to prevent the ground portion of the recycled paper from becoming a dot when binarized, Even when a recycled paper document is read, noise can be suppressed.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.

[0027]

As described above, according to the present invention, the reading
Whether the original to be removed is high-quality paper or recycled paper
The execution of the edge enhancement process can be controlled based on the
Adaptive edge emphasis according to the paper quality of the manuscript becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a Laplacian filter.

FIG. 3 is a block diagram showing an internal configuration of a line buffer unit 1 and a register unit 2 according to the first embodiment.

FIG. 4 is a diagram illustrating an example of a pattern of a recycled paper document;

FIG. 5 is a flowchart illustrating the operation according to the first embodiment.

FIG. 6 is a block diagram showing an internal configuration of the edge enhancement processing circuit 3 according to the first embodiment.

FIG. 7 is a block diagram showing an internal configuration of an edge enhancement processing circuit according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line buffer part 2 Register part 3 Edge emphasis processing circuit 3-1 Operation circuit 3-2 Sign determination circuit 3-3 Multiplier 3-4 Adder 3-5 Selector 4 Operation part 5 Binarization circuit 6 Original reading part 7 CPU 8 ROM 9 RAM 101, 102 Line buffer 201-209 Register

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (3)

(57) [Claims] When a high- quality paper is designated as a medium of a document to be read, a process of emphasizing an edge amount of image data obtained by reading the document is performed. If recycled paper is specified as the medium, whether to execute processing for enhancing the edge amount based on the edge amount of image data obtained by reading the original document
An image processing method characterized by determining 2. The image processing method according to claim 1, wherein the designation of the type of the medium of the document is performed from an operation unit of an apparatus that executes the image processing method. 3. A process for enhancing the edge amount is performed.
In determining whether or not to do so, the edge amount of the image data
If the sign of is negative, the processing to emphasize the edge amount is performed.
If the sign of the edge amount is positive, the edge amount
It is decided not to execute the process to emphasize
The image processing method according to claim 1.