JPH09331454A - Image processing device - Google Patents

Abstract

(57) Abstract: An image processing apparatus having various restoration processing functions according to various isolated points is obtained. A digital image signal B is binarized in a binarizing circuit 31 at an appropriate slice level to generate a signal a. In the signal a, a = 1 corresponds to black and a = 0 corresponds to white. Further, the signal a is delayed by the main / sub delay circuit 32 in various sizes in pixel units in the main scanning direction and the sub scanning direction. The signals b, c and d are various delayed signals.
The isolated point detection circuits 33, 34 and 35 each detect an isolated point (black) having a predetermined shape, and when there is an isolated point, each of the signals e, g and h outputs "0" (= L level). . The selection circuit 36 responds to the input from the operation unit to turn on / off the isolated point removal function and to the signal F indicating the degree of its strength, and the isolated point signal j generated from the signals e, g, and h. Is output.

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 more particularly to an image processing apparatus having a special function of improving image quality in a digital copying machine, a fax machine, a scanner, etc. The present invention relates to an image processing device that obtains a reproduced image with a clean background.

[0002]

2. Description of the Related Art Conventionally, an image processing apparatus such as a copying machine has been improved in image quality, and one having a special function for improving image quality has appeared. For example, it is a function of removing a noise image in a document to obtain a reproduced image with a clean background.

As a more specific conventional example relating to the above function, there is JP-A-2-294878. In this conventional example,
Detects and removes the input isolated points and performs bag character processing. According to this processing, it is possible to reproduce a high-quality image that is not affected by noise and the like with a simple configuration.

[0004]

However, there are various shapes and sizes of scattered isolated points. In the above-mentioned conventional example, there are limits to the repair processing function of these various isolated points. For example, there are problems such that only isolated points of a specific type can be removed, or the isolated point removal process always works, and even if there is an isolated point image that should not be removed, it is removed.

It is an object of the present invention to provide an image processing apparatus having various restoration processing functions according to various isolated points.

[0006]

In order to achieve the above object, the image processing apparatus of the present invention comprises an image processing means for dividing an image into read pixels to obtain digital image data, and an isolated predetermined pixel in the image data. It is characterized by having an isolated point removing means for removing isolated points formed by numbers and an operating means for inputting an instruction to turn on / off the removing function of the isolated point removing means.

Further, the above image processing apparatus has a gradation processing means for performing at least two kinds of gradation processing, and the removal function of the isolated point removing means is based on the gradation processing result processed by this gradation processing means. It is advisable to selectively set ON / OFF of.

Further, the isolated points formed by the above-mentioned predetermined number of pixels are formed by a matrix of pixels of a specific color,
There are a plurality of types of matrix configurations, and the plurality of types of configurations may be stored in advance in the image forming apparatus.

Further, the operating means is provided together with the operating portion for operating the image forming operation of the image processing apparatus, and the ON / OFF of the removing function is set to the initial value on the OFF side. It is preferable that the selection can be set by the operating means.

The operation means is provided with a character mode key which is selectively set when handling a character image and a photo mode key which is selectively set when handling a photographic image.
ON / OFF of the removal function may be preferentially set by the selection setting of the character mode / photo mode.

Further, the above-mentioned image forming apparatus has an area designating means capable of arbitrarily designating the area of the read image, and the removal function of the isolated point removing means is provided for each area designated by the area designating means. ON / OFF selectively, or
It is preferable that either ON / OFF of the removal function or at least two types of gradation processing can be selectively set.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an image processing apparatus according to the present invention will be described in detail with reference to the accompanying drawings. Figure 1
Referring to FIG. 13, there is shown an embodiment of the image processing apparatus of the present invention. FIG. 1 is an external perspective view in which the present invention is applied to a digital copying machine, FIGS. 2 to 4 are block diagrams for explaining the configuration of the digital copying machine, and FIGS. 5 to 7 explain the operation of an isolated point detection circuit. FIGS. 8 and 9 are configuration diagrams of the logic circuit, and FIG. 10 is a diagram for explaining the operation unit. In addition, FIGS. 11 to 13 are diagrams illustrating a modification example.

In the digital copying machine of FIG. 1, a document set on the document table with the surface to be read facing downward is read by the reading means inside the apparatus, and the read image data is various types including this embodiment. After the image processing is performed, the reproduction image is recorded by the writing unit. The main scanning for reading is electronically performed by the CCD line sensor, while the sub-scanning is performed by the relative position movement between the document and the CCD line sensor. Further, both reading and writing are performed by being decomposed into pixels, and the resolution is 400 DP for both main scanning and sub scanning.
I (dot per inch). On the operation unit, various operation keys for instructing and inputting operation types and operation conditions of the apparatus, and various items for operation are arrayed and displayed. The digitizer is a tool that can arbitrarily specify the area of the read original image.

FIG. 2 shows the digital copying machine of FIG.
FIG. 3 is a circuit configuration block diagram showing a processing unit of image data from reading a document to recording a reproduced image, and showing a flow of control signals of each unit. The circuit configuration unit of FIG.
1, an image processing unit 12, a writing unit 13, a control unit 14, and an operation unit 15. This circuit configuration unit is mounted inside the image processing apparatus according to the embodiment.

The image signal from the CCD line sensor forming the reading section 11 is subjected to processing such as amplification, AD conversion, shading correction and the like. In the image processing unit 12, in addition to filter processing, scaling processing, gradation processing, etc., isolated point removal according to this embodiment is performed. In the writing unit 13, such as modulation of the laser beam, recording on the photoconductor, development, transfer, fixing,
Image recording is performed by a so-called laser beam printer. From the operation unit 15, conditions such as gradation processing mode, recorded image density, and scaling ratio, and “strength” of isolated point removal are set and input, and by a control signal from the control unit 14 based on these conditions, The operations of the reading unit 11, the image processing unit 12, and the writing unit 13 are controlled. The symbols A and E shown in FIG. 2 are image signals.

The digitizer 16 is capable of visually designating an area of an image by XY coordinates, and sets the area using an operation pen or the like in the interlocking display with the monitor screen display. In the digitizer 16, a conventional method such as an optical method or pressure detection may be used to detect the designated coordinates. Further, the area designated by the digitizer 16 can be used for limiting the area of isolated point removal processing executed in the following description, changing the processing condition for each area, and the like.

FIG. 3 shows more detailed internal functional blocks of the image processing unit 12 of FIG. This functional unit includes a filter unit 21, an isolated point removing unit 22, a scaling unit 23, and a gradation processing unit 24. Further, the signals A, B, C, D and E are image signals and represent 256 gradations with 8 bits. The symbols A and E represent the same signals as in FIG. Further, the symbol F is a signal indicating ON / OFF of the isolated point removing function in response to the input from the operation unit 15 and the degree of its strength. Further, the symbol G is a region signal designated by the digitizer 16. Each of the filter unit 21, the variable power unit 23, and the gradation processing 24 may have a known configuration and components.

FIGS. 4 to 9 are views for explaining the internal structure of the isolated point removing section 22 shown in FIG. 3 and its operation and action. In FIG. 4, 31 is a binarization circuit, 32 is a main / sub delay circuit, 33 to 35 are isolated point detection circuits, 36 is a selection circuit, 37 is a main / sub delay circuit, and 38 is a mask circuit.

The 8-bit 256-gradation image signal B is binarized by a binarizing circuit 31 at an appropriate slice level to generate a signal a. As for the signal a, when a = 1 is black, a = 0
Corresponds to white. Further, the signal a is delayed by the main / sub delay circuit 32 in various sizes (units are pixels) in the main scanning direction and the sub scanning direction. The signals b, c, and d are various delay signals, and are a signal group of delay amounts required by the isolated point detection circuits 33, 34, and 35, respectively.

The isolated point detection circuits 33, 34, and 35 detect isolated points (black) having a predetermined shape, and when there are isolated points, the signals e, g, and h are "0" (= L level). Is output. The selection circuit 36 responds to the input from the operation unit 15 to ON / OFF of the isolated point removal function and to the signal F indicating the degree of strength thereof, and creates the isolated point signal generated from the signals e, g, and h. Output j. It should be noted that these signals are j = 0 (L level) at an isolated point.

The main / sub delay circuit 37 is a circuit for delaying the image signal B by an amount corresponding to the signal j to obtain the image signal G. The mask circuit 38 outputs the signal G when the signal j = 0.
This is a circuit for masking = 0 (meaning white). That is, isolated points are removed even in a multi-valued image signal. The image signal E is an 8-bit image signal with isolated points removed.

The binarization circuit 31 and the main / sub delay circuit 32
There are various known examples of the isolated point detection circuits 33, 34 and 35. For example, JP-A-62-104372 describes an embodiment of binarization, main / sub delay, and isolated point detection. Further, Japanese Patent Laid-Open No. 2-294878 describes an embodiment of the isolated point detecting means.

FIG. 5 shows the operation of the isolated point detection circuit 33 shown in FIG.
It is a figure for explaining an operation. In FIG. 5, each square corresponds to a pixel, and a signal corresponding to each pixel of a matrix of main and sub 5 pixels is obtained from the main and sub delay circuit 32. When all of the ◯ -marked pixels in FIG. 5 are 0 (white), the X-marked pixel is an isolated point regardless of its state (0 or 1), and the signal e = 0 (L Level). Otherwise e = 1
It is.

FIG. 6 corresponds to the isolated point removing circuit 34 of FIG. 4. When all the pixels marked with ◯ are 0, the pixels marked with X are isolated points regardless of their states, and the signal g = 0.

FIG. 7 corresponds to the isolated point removing circuit 35 of FIG. 4, and when all the pixels of the ◯ mark are 0, the pixels of the X mark are detected as isolated points regardless of the state, and correspond to the pixels of the X mark. Signal h = 0.

That is, the isolated point detection circuits 33, 34, 3
5, the isolated point detection circuit 33 is an isolated point having a size of 1 pixel, the isolated point detection circuit 34 is an isolated point having a size of 2 × 2 pixels or less, and the isolated point detection circuit 35 is 3 × 3 pixels or less. Each isolated point of size is detected. However, these are examples, and the isolated point detection size (range) can be set to another size.

FIG. 8 shows the internal logic of the selection circuit 36 in FIG. Signals e, g, h, j are the same as in FIG. 4, and signals f0, f1 are details of signal F in FIG. That is, the signal F is a 2-bit signal composed of f0 and f1. The selector 61 selects any one of the signals A, B, C and D according to the conditions of the signals f0 and f1 input to s0 and s1 and outputs it to the output terminal Y. Input signal A is always 1 (H
Level), which corresponds to the isolated point removal function OFF in the initial state. Signals s1 (f1) and s0 in other states
The correspondence between the logic configuration of (f0) and the output signal Y is as shown in the table below.

[0028]

[Table 1]

FIG. 9 shows the internal logic of the mask circuit 38 in FIG. The signals G0 to G7 are the respective bit signals of the 8-bit signal G, G0 being the LSB and G7 being the MSB.
The signal j is the same as j in FIGS. 4 and 8 and is an isolated point signal. The signals E0 to E7 are each bit signals of the 8-bit signal E,
E0 is the LSB and E7 is the MSB. By the AND gate, when j = 0 (L level), all of E0 to E7 become 0 (white) regardless of the state of G0 to G7. That is, when an isolated point is detected, the image at the position of the isolated point is corrected to white.

FIG. 10 shows the operation keys and the display for the operation of the operation section 15, particularly the portion related to the present embodiment. The characters "MAKE UP" and a rectangular box in the figure mean an isolated point removal function, and are called "MAKE UP function" or simply "MAKE UP" for the purpose of being easy to understand and familiarize with. The other characters “L”, “M”, and “H” indicate operation keys, and the characters L, M, and H are displayed on the key top as shown in FIG. Below each key top, there is a light emitter that emits light when the key is selected to indicate that it is selected. For example, in the initial state, none of the keys L, M, and H are selected and do not emit light.
The UP function is OFF.

At this time, the signals f0 = 0 and f1 = 0.
Press the key "L" to enter L (LOW) for the MAKE UP function.
Is selected and light is emitted. Correspondingly, the isolated point removal function selection signal F becomes f0 = 1 and f1 = 0. Therefore, the isolated points of the pattern of FIG. 5 are targeted for removal.

When the key "L" (or M, H) is selected and is emitting light, by further pressing the key, the selection can be canceled and the emission can be turned off. When another key is pressed while any key is selected, the selection is switched to the newly pressed key, and the light emission is switched accordingly.

The key display "L" in FIG. 10 is an abbreviation for Low, the display "M" is for Middle, and the display "H" is for High, which expresses the degree of action of the isolated point removal function.

Correspondences between keys "L", "M", and "H" and isolated points to be removed are L / matrix of the configuration shown in FIG. 5, M / configuration shown in FIG. 5 or FIG. , H / matrix having the configuration shown in FIG. 5, FIG. 6 or FIG.

"L" as an isolated point removing function in this apparatus,
The reason for providing the four levels of "M", "H" and the removal function OFF will be described below.

Generally, there are various kinds of originals and their images used in copying machines, and there are various kinds of small isolated point images which can be considered as image noise or unnecessary images. For example, in the case where an image copied by a copying machine is used as an original, there are many small isolated points on the original that are hard to be noticed by the naked eye due to the performance of the copying machine. That is, in the process of copying, the toner is unnecessarily scattered and adheres to the copy sheet, resulting in an isolated point image. When such an image is copied as an original, it may be read as an isolated point having a size of 1 pixel or more because it is read at a resolution of 400 DPI. As a result, in the reproduced image, the size of the isolated point further increases or the number of isolated points increases, and the quality of the reproduced image deteriorates.

Not limited to the above reasons, there are numerous causes of isolated point images. For example, printed matter, documents created by word processors, documents handwritten with pencils, drawings, paintings, photographs, and copies of these images. Depending on the image, the shape, property, and number of isolated points may differ, or the need for removing isolated points may differ. In some cases it may be better not to remove. In order to meet various needs for such isolated point removal, in this embodiment, four levels including OFF are provided as described above.

According to the above-described embodiment, for a document including or possibly including isolated points which should not be removed,
ON / OFF of the isolated point removal function can be freely selected and set. A plurality of types of contents of the removal function are provided in the isolated point detection circuit, and these contents can be freely selected. This operation can be performed on the operation unit. In the initial state when the power is turned on, it is automatically set to the OFF side, and it is easy to check whether or not the function is executed. Furthermore, the above-mentioned plural kinds of isolated point removal functions may be set in relation to the area designated by the digitizer.

11 to 13 are views showing a modification of the present invention. FIG. 11 shows a part of the operation unit, and these are keys for selecting and setting the image quality mode. Under the "Picture Mode" display, press the "Character" key and the "Photo" key.
One operation key is arranged. The "character" key selects a character mode, and in the character mode, gradation processing suitable for a line image such as a character is performed in the gradation processing unit. Further, the "photograph" key instructs to select a photo mode, and in the photo mode, gradation processing suitable for a gradation image such as a photograph is performed.

FIG. 12 shows a circuit configuration example 1 of this variation. The circuit shown in FIG. 12 is applied to this variation example as shown in FIG.
Only the changed part of the circuit corresponding to is shown. Therefore, it is configured with the same circuit as that of FIG.

The signal f2 in FIG. 12 is a signal generated in association with the "image quality mode" key of the operation unit. That is, f2 = 0 (level = L) in the character mode, and f2 = 1 (level = H) in the photo mode. As is apparent from the logic of FIG. 12, j1 = j only in the character mode, and j1 = H in the photo mode regardless of j.

This j1 is input to the mask circuit 38 and corresponds to the signal j in FIG. That is, when the image quality mode is the character mode, the isolated point removal function is instructed to be ON, and "MAKE
When the "UP" key is ON for the isolated point removal function, the isolated point removal function is actually enabled.

FIG. 13 further shows a circuit configuration example 2 of this variation.
Is represented. This circuit configuration example 2 is also a partial modification of FIG. 4 similarly to the above-described circuit configuration example 1, and is configured by the same circuit as FIG. 4 except for the illustration.

The signals f0 and f1 in FIG. 13 are the same as those in FIG. 8, and if any one of L, M and H of the "MAKE UP" key is selected, the signal is at least one of f0 and f1. Is 1. Therefore, the signal k = H.
When the signal k = H, the signal 1 = f2, that is, 1 = L in the character mode and 1 = H in the photo mode. 1 = L
In the (character mode), j2 = j, and the isolated point removing function is effective. Further, when 1 = H (photograph mode), j2 = H regardless of j, and isolated point removal does not work.

On the other hand, "MAKE UP" key L, M,
When none of H is selected, both f0 and f1 are at level L, and at this time the signal k = L. That is, when k = L, the signal 1 = L regardless of L / H of f2. When signal 1 = L, signal j2 = j by OR gate
become. This j2 is input to the mask circuit 38 and corresponds to the signal j in FIG. At this time, since both f0 and f1 are 0, the signal j = H according to FIG. That is, j2 = H, and the isolated point removing function is not activated.
That is, in the isolated point removal function, "MAKE UP"
In this example, the key has a higher priority than the image quality mode key.

The present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made.
For example, the configuration of the isolated point removal unit is not limited to that shown in FIG. 4, and various methods and configurations are possible. The shape of the target isolated point is not limited to those shown in FIGS. 5 to 7, and various modifications are possible. The configuration of the operation unit, the key arrangement, the name and the display can be variously modified, and the level of the strength of the isolated point removing function is not limited to the above-described embodiment, and can be variously modified.

[0047]

As is apparent from the above description, the image processing apparatus of the present invention decomposes an image into read pixels to form digital image data, and an isolated point formed by a predetermined number of isolated pixels in the image data. To remove. An instruction is input to turn on / off the isolated point removing function. Therefore, it is possible to select whether or not to execute the isolated point removal processing. Furthermore, it becomes possible to selectively set the characteristics of the isolated point removal function.

[Brief description of drawings]

FIG. 1 is an external perspective view of an embodiment in which an image processing apparatus of the present invention is applied to a digital copying machine.

FIG. 2 is a main configuration block diagram of the embodiment of FIG.

FIG. 3 is a block configuration diagram in which the image processing unit in FIG. 2 is expanded.

FIG. 4 is a block configuration diagram in which an isolated point removing unit in FIG. 3 is expanded.

FIG. 5 is a diagram for explaining an operation example 1 of the isolated point removing unit shown in FIG. 3.

FIG. 6 is a diagram for explaining an operation example 2 of the isolated point removing unit shown in FIG.

7 is a diagram for explaining an operation example 3 of the isolated point removing unit shown in FIG. 3. FIG.

8 is a circuit diagram showing an example of a logic configuration of a selection circuit of FIG.

9 is a circuit diagram showing a logic configuration example of the mask circuit of FIG.

FIG. 10 is a plan view showing an arrangement configuration example of operation keys of an operation unit.

FIG. 11 is a diagram showing a configuration example of a key which is a part of the operation unit and is used to selectively set an image quality mode.

12 is a block diagram showing a modification unit of FIG. 4 which is a circuit configuration example 1 of a modification example.

13 is a block diagram showing a modification unit of FIG. 4 which is a circuit configuration example 2 of a modified example.

[Explanation of symbols]

 11 reading unit 12 image processing unit 13 writing unit 14 control unit 15 operation unit 16 digitizer 21 filter unit 22 isolated point removing unit 23 scaling unit 24 gradation processing unit 31 binarization circuit 32 sub-delay circuit 33, 34, 35 Isolated point detection circuit 36 Selection circuit 37 Main / sub delay circuit 38 Mask circuit 61 Selector

Claims (10)

[Claims] 1. An image processing means for decomposing an image into read pixels to obtain digital image data, an isolated point removing means for removing an isolated point formed by a predetermined number of isolated pixels in the image data, and the isolated point. An image processing apparatus comprising: an operation unit for inputting an instruction to turn ON / OFF the removal function of the point removal unit. 2. The image processing apparatus further comprises gradation processing means for performing at least two kinds of gradation processing, and the isolated point removal means is operated by the gradation processing result processed by the gradation processing means. The image processing apparatus according to claim 1, wherein ON / OFF of the removal function is selectively set. 3. The image processing apparatus according to claim 1, wherein the isolated points formed by the predetermined number of pixels are formed by a matrix of pixels of a specific color. 4. The matrix has a plurality of types of configuration forms, and the plurality of types of configuration forms are stored in advance in the image forming apparatus. The image processing device described. 5. The image forming apparatus according to claim 1, wherein the operation unit is provided together with an operation unit that operates an image forming operation of the image processing apparatus. 6. The initial value of ON / OFF of the removal function is set to the OFF side.
The image forming apparatus according to any one of items 1 to 5. 7. The image forming apparatus according to claim 1, wherein a configuration form of the plurality of types of matrices can be selected and set by the operation unit. 8. The operation means is provided with a character mode key that is selectively set when handling a character image and a photo mode key that is selectively set when handling a photographic image,
8. The image forming apparatus according to claim 1, wherein ON / OFF of the removal function is preferentially set by the selection setting of the character mode / photograph mode. 9. The image forming apparatus further comprises area designating means capable of arbitrarily designating an area of the read image, and removal of the isolated point removing means for each area designated by the area designating means. 9. The image forming apparatus according to claim 1, wherein ON / OFF of the function can be selectively set. 10. The removal function ON / OFF or the at least two types of gradation processing can be selectively set for each area designated by the area designating means. Item 9. The image forming apparatus according to Item 9.