JP2001053964A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of forming a high-quality image even in the case of setting the inside and outside of an area designated by a user to a same original type. SOLUTION: In the case of having designated a specific area from a user interface (UI) 14 and having set the same 'character' as an original type (the kind of an image) with respect to both of the inside and outside of the specific area, in an image processing part, a decoder 136 for decoding an area signal outputted from an editing circuit 132 and a TI(text image) separating result outputted from a TI separation circuit 134 to a picture adjusting parameter forcedly sets the picture adjusting parameter depending on the TI separating result with respect to the outside of the specific area. Then, image forming is executed based on this picture adjusting parameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, and more particularly to a binary image area and a halftone image for a document in which a binary image such as a character and a halftone image such as a photograph are mixed. The present invention relates to an image forming apparatus capable of copying by designating an image area and designating a gradation for each area.

[0002]

2. Description of the Related Art Generally, a document to be copied, such as a flyer, often includes a binary image such as a character and a halftone image such as a photograph. Therefore, when forming an image based on the original, it is necessary to identify the binary image area and the halftone image area and to perform appropriate image processing on each area in order to form a high-quality image. It is.

[0003] From such a viewpoint, T is used to identify whether the image of the area to be copied is a character image or a picture image.
2. Description of the Related Art A method of identifying an image type of a region using (Text) I (Image) separation and setting an optimal image quality adjustment parameter based on the identification result to form an image has been conventionally used.

However, even in this TI separation process, when an original image is read by an image scanner using a CCD (Charge Coupled Device) sensor or the like,
Since the reference size (the number of pixels to be referred to) is limited, erroneous recognition may occur, for example, the recognition target area may be recognized as a character area despite being a picture area.

On the other hand, instead of relying only on TI separation, a user specifies a specific area of a document, and forcibly sets a document type (character image / picture image) of the specified area. Techniques are also known.

As a specific example, in the prior art 1, for example, in a document mainly composed of characters, when a character having a low density such as a pencil is present in a part of the document, an area of the character portion is designated and the designated region is designated. The document type of the area was forcibly set to "character". At this time, since the original is mainly composed of characters, it goes without saying that “characters” are set outside the designated area.

That is, as shown in FIG. 14A, an area 101A is designated, the inside of the area 101A is set to a character screen (400 lines), and the area 101B outside the area 101A is also set to a character screen (400 lines). Line). As a result, even a character having a low density in the area 101A can be reproduced as a clear character.

[0008]

However, if the document type is set to "character" for both the inside and outside of the designated area, the image quality adjustment parameters for characters are forcibly set. In the case where a picture image such as a scene is mixed in the original document, the pattern image is also processed based on the image quality adjustment parameter for characters, and thus there is a problem that the reproducibility of halftone is deteriorated.

On the other hand, the inside 101 of the designated area
As shown in FIG. 14B, a technique in which the document type is set to “character” for both the A and the external 101B also depends on the identification result of the TI separation as shown in FIG. However, in the prior art 2, although the reproducibility can be improved for the picture image mixed in the area 101B outside the designated area 101A, the determination result of the TI separation is also applied to the characters in the designated area 101A. Is reflected, so that there is a problem that the image quality is remarkably deteriorated when there is an erroneous recognition in the TI separation.

Further, as an image forming apparatus for distinguishing between a binary image area and a halftone image area and forming an image corresponding to each area, an image forming apparatus disclosed in JP-A-7-203194 and an image forming apparatus disclosed in An image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 271327/1991 is proposed.

However, the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 7-203194 has a configuration in which an image is formed by setting appropriate image quality adjustment parameters inside and outside a region. If the outside is of the same original type, the same image quality adjustment parameters will be set, and consequently, the same problem as in the prior art 1 will occur.

On the other hand, in the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 10-271327, when the designated area is set to "character", the determination parameter for TI separation is changed until the area is determined to be "character". Since the determination parameter for the TI separation is effective even outside the area, the halftone image is also determined based on the character.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to form a high-quality image even when the same document type is set inside and outside a region designated by a user. To provide a simple image forming apparatus.

[0014]

In order to achieve the above object, according to the present invention, an area is designated for a document, an image type of the designated area is set, and the inside and outside of the designated area are set. In the image forming apparatus capable of outputting with different image quality adjustment parameters, even when the same image type is set inside and outside the designated area, printing is performed with different image quality adjustment parameters.

In the image forming apparatus having the above configuration, when the same image type is set for the inside and outside of the designated area, even if an image having a different image quality from the image inside the area is mixed in the image outside the area. By setting image quality adjustment parameters different from those inside the region for images of different image quality outside the region, processing according to the image quality is performed.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of, for example, a digital copying machine which is an image forming apparatus according to the present invention.

In FIG. 1, the system control unit 11 has a CP
U and the like, and controls the entire system, specifically, controls the document reading unit 12 and the image processing unit 13. The user interface (UI) 14 is provided for the user to input various setting information in copying. From the user interface 14, in addition to various types of information such as the document size and the number of copies, region information for designating a region of the document, image type (document type) information of the designated region, and the like are input. It is supplied to the system control unit 11.

The CCD sensor 15 constitutes an image scanner, reads image information of a document (not shown), and
It is supplied to the document reading unit 12 as an analog image signal of (red) G (green) and B (blue). The document reading unit 12 includes an A / D converter 121, a CCD control circuit 122, a signal processing circuit 123, and the like.

In the document reading section 12, an A / D converter 121 converts an analog RGB signal supplied from the CCD sensor 15 into a digital RGB signal, and
It is supplied to the control circuit 122. The CCD control circuit 122 includes:
Correlated double sampling (C
DS) and the like, and then supplies the signal to the signal processing circuit 123. The signal processing circuit 123 performs various signal processing such as shading correction and gray balance correction on the digital RGB signals.

The RGB signals output from the document reading unit 12 are temporarily stored in an image memory 16 and then stored in an image processing unit 13.
Supplied to The image processing unit 13 includes a color space conversion circuit 13
1. Editing circuit (board) 132, color conversion circuit 133, TI
Separation circuit 134, enlargement / reduction circuit 135, decoder 13
6. Filter 137 and TRC (Tone Reproduction
Correction; gradation correction) circuit 138 and the like.

[0021] In the image processing unit 13, a color space conversion circuit 131, the RGB signals supplied from the image memory 16 to the color space conversion to L ^* a ^* b ^* signal, the L ^* a ^* b
^{* The} signal is supplied to the editing circuit 132. The editing circuit 132 expands the area information set by the user interface 14 and provided through the system control unit 11 with respect to the L ^* a ^* b ^* signal, and based on the area information, generates the area signal and the original type (image type). Output information.

Here, the area signal will be described in detail. If the area signal is a 4-bit signal, for example, the area is 16 bits.
(= 2 ⁴ ). Therefore, FIG.
In this case, if the entire surface of the document is set to an area signal 0 (0000), 15 specific areas can be set. Here, a case where two specific areas 1 and 2 are designated is shown as an example. Then, the area signal 1 (000
1) The area signal 2 (0010),...
In other words, the editing circuit 132 generates an area signal for each area.

The color conversion circuit 133 converts the L ^* a ^* b ^* signals into Y (yellow), M (magenta), C (cyan), K (black)
The YMCK signal is color-converted into a signal, and the YMCK signal is
35. The TI separation circuit 134 discriminates whether the image of the document is a character image that is a binary image or a picture image that is a halftone image, and compares the TI separation result together with the area signal with the color conversion circuit 133 and the enlargement / reduction. The signal is supplied to the circuit 135.

The enlargement / reduction circuit 135 performs enlargement / reduction processing on the YMCK signal, and supplies the result to the decoder 136. The decoder 136 is a feature of the present invention, and decodes the area signal supplied through the enlargement / reduction circuit 135 into a duck signal for setting an image quality adjustment parameter corresponding to the area signal. The specific circuit configuration of the decoder 136 will be described later. The image quality adjustment parameters include a filter coefficient, a gradation correction curve (TR
C), the screen ruling is used.

The filter 137 performs a filtering process on the YMCK signal to sharpen a picture or a character or to remove a halftone dot of a printed document to prevent an unsightly moiré pattern. In the filtering process, a process of calculating a joint product (moving average) between a certain filter coefficient and image data is performed. The TRC circuit 138 converts density or brightness data which is a characteristic value inside the image processing unit 13 into
The area ratio of the characteristic value of the image output unit 17 is converted.

The screen signal and image data output from the image processing unit 13 are supplied to an image output unit 17. The image output unit 17 includes an output control unit 171 that controls the time-series image data from the image processing unit 13 to generate a screen (600 lines / 200 lines) according to a screen signal, and a one-dimensional signal. 172 which reproduces a two-dimensional image on a recording medium (not shown) such as paper
And a configuration having:

Decoder 1 which is a feature of the present invention
FIG. 3 shows an example of the 36 configuration. In this figure, this decoder 136 has two logic RAMs (Randam Acces
s Memory) 201, 202.
In the logic RAM 201 in the preceding stage, a TI separation circuit 134 is provided.
Is input as an address.

The logic RAM 201 stores a document type (DTYPE) and a photographic paper (DPS) based on the area signal.
P), the same document type specific area (DCFILL) is output as a tag signal. As an example, in FIG. 2, the document type (image type) is used for both the entire document and the specific areas 1 and 2.
Is set to "character", a tag signal as shown in FIG. 4 is obtained. This tag signal is output to the logic RAM
202 is supplied as an address.

FIG. 5 shows a specific internal configuration of the logic RAM 201. As is apparent from FIG.
The AM 201 has an 8-bit configuration, and decodes (DTYP) a 4-bit area signal [3: 0].
[1: 0], DPSP, DCFILL, DEC [3:
0]). However, DEC [3: 0] is not used.

A tag signal DTYP given from the preceding logic RAM 201 is stored in the subsequent logic RAM 202.
E, DPSP, DCFILL, TI separation circuit 13
4, the processing result (TI) of TI separation and the color mode (MODE) are input as addresses.
The logic RAM 202 selects a filter coefficient selection (SE), which is an image quality adjustment parameter, based on the input information.
RC selection (TRC) and screen selection (SCRN)
Output each information.

FIG. 6 shows a specific internal configuration of the logic RAM 202. As is apparent from FIG.
AM 202 has a 16-bit configuration, and DTYP
[1: 0], DPSP, DCFILL, TI [1:
0] and MODE [1: 0] are decoded (SE
[2: 0], LH [2: 0], TRC [3: 0], SC
RE [1: 0]) is set. However, of the 16 bits, the upper 4 bits are unused. The input address configuration is as shown in FIG.

In the logic RAM 202, since the input addresses are different between the area signal 0 and the area signals 1 and 2, different outputs are obtained. As an example, MO
When DE [1: 0] = 00 and TI [1: 0] = 00,
The address of the logic RAM 202 is as follows. Area signal 00000000001 = 001H Area signal 10000010001 = 021H Area signal 2000000001 = 021H Note that H represents a hexadecimal number.

When the area signal is 0 (the entire original), the output of the logic RAM 202 depends on the processing result [TI] of the TI separation. That is, TI [1: 0] = 0
According to 0, 01, 10, and 11, filter coefficient selection (S
E), TRC selection (TRC) and screen selection (S
CRN) changes. The address at this time is Then, data is written at this address.

Further, with respect to the area signal 1, the area signal 1 does not depend on the processing result [TI] of the T1 separation. Write the same data to all of the addresses. Thus, the image quality adjustment parameters to be set are the same regardless of the processing result [TI] of the TI separation.

This is, for example, as shown in FIG.
When "character" is set as the original type for the entire original and for the specific areas 1 and 2, the decoder 136
Although image quality adjustment parameters corresponding to characters are set for the specific regions 1 and 2, image quality parameters dependent on the TI separation processing result [TI] are compulsorily set for the entire original (outside the specific regions 1 and 2). Means that.

Next, the operation of each section in the copying process in the digital copying machine having the above configuration will be described.

First, a procedure when the user sets and inputs various information from the user interface (UI) 14 prior to the copying process will be described with reference to the flowchart of FIG.

If it is necessary to adjust the image quality (step S11), sharpness and color balance are set from the UI screen (step S12). Next, the document type (image type) of the entire document is displayed on the UI screen shown in FIG. 9 by text / photo (Aoto Photo & Text), text (Text),
A photograph (Photo) and a map (Map) are selected (step S13). Here, for example, a “character” mode is set.

In the UI screen shown in FIG. 9, "Normal
By selecting "Text", the setting that the character is a normal density character is performed, and by selecting "Light Text", the setting that the character is a light character such as pencil writing is performed.

When a specific area is set in the document (step S14), the coordinates (x1, y1) of the upper left corner and the coordinates (x2, x2) of the upper left corner of the specific area are displayed on the UI screen shown in FIG. , Y2) is set (step S15). Note that the specific area can be set by specifying a pen from an editor pad (EDITOR PAD). Subsequently, the document type of the specific area is set from the UI screen (step S16). Here, for example, a “character” mode is set.

When the above-mentioned setting input by the user is completed, under the control of the system control section 11, the area is developed and the image quality adjustment parameters are set. The procedure will be described below with reference to the flowchart of FIG.

First, upon completion of the setting input by the user, the user interface 14 notifies the system control unit 11 of the set image quality adjustment contents, base document type, coordinates of the specific area, and document type of the specific area. (Step S21). Upon receiving this, the system control unit 11 notifies the image processing unit 13 of the image quality adjustment content and its level, the base document type, the coordinates of the specific area, and the document type of the specific area (step S22).

In response, the image processing unit 13 first develops the area information in the editing circuit 132 (step S
23). Specifically, as shown in FIG. 2, the specific area is developed on the entire surface of the document based on the coordinates of the specific area set and input in advance. Here, a case where two specific areas 1 and 2 are set and input is shown as an example. Subsequently, image quality adjustment parameters for each area are set (step S2).
4).

Next, the procedure of the actual copying operation will be described with reference to the flowchart of FIG.

When the reading of the original by the CCD sensor 15 is started, the RGB output from the CCD sensor 15
The signal is supplied to the image processing unit 13 via the document reading unit 12 and the image memory 16 (Step S31). This RG
The B signal is converted into an L ^* a ^* b ^* signal by a color space conversion circuit 131 and supplied to an editing circuit 132. Editing circuit 13
In step 2, an area signal corresponding to each area is generated based on the area information developed in advance, and output in synchronization with the L ^* a ^* b ^* signal (step S32).

The TI separation circuit 134 performs a TI separation process for discriminating whether the input image signal is for a character area or a picture area, and outputs the processing result [TI]. Processing result of area signal and TI separation [TI]
Is supplied to the decoder 136 via the enlargement / reduction circuit 135 in synchronization with the YMCK signal color-converted from the L ^* a ^* b ^* signal in the color conversion circuit 133.

As described above, the decoder 136 decodes the area signal and the processing result [TI] of the TI separation, and selects a filter coefficient (S) as an image quality adjustment parameter.
E), TRC selection (TRC) and screen selection (S
CRN) is output. In this example, since “character” is set as the document type in the entire document and in the specific areas 1 and 2 in FIG.
As shown in FIG. 13, the image quality adjustment parameter corresponding to the character for the specific area 21 (60 lines as screen ruling)
0 line), but the entire original (outside the specific area)
With regard to 22, an image quality parameter dependent on the processing result [TI] of the TI separation is forcibly set.

After that, the specific areas 1 and 2 correspond to characters,
In the other areas, the filter 137, the TRC circuit 138, and the image output unit 1 at the subsequent stage are based on the image quality adjustment parameters set respectively depending on the processing result of the TI separation.
7, the adaptation process is performed for each area (step S34). That is, in the specific areas 1 and 2 in FIG. 2, the processing corresponding to the character is forcibly performed, and in the other areas, the processing corresponding to the type of the image is performed. Then, based on the image data on which these processes have been performed, the printer 17
An image is formed in Step 2 (Step S35).

As described above, in the image forming apparatus such as a digital copying machine, when the same "character" is set as the document type for the inside and outside of the designated specific area, the outside of the area is forcibly forcibly set. By printing with the image quality adjustment parameter depending on the TI separation result, even if a picture image such as a scene is mixed and mixed in a character image outside a specific area, a processing according to the picture quality is performed on the picture image. Is performed, the reproducibility of the halftone is improved, and a pattern image with rich gradation can be reproduced.

On the other hand, in the specified specific area, "text" is set as the document type, and the process is performed in which the gradation is forcibly provided. By designating a portion of a character with a light color as a specific area, it can be reproduced as a clear character. Naturally, the processing corresponding to the character image is performed on the character image outside the specific area based on the processing result of the TI separation, so that a clear character can be reproduced.

In the above embodiment, when the same "character" is set as the document type for the inside and outside of the specific area, the image quality forcibly depends on the TI separation processing result for the outside of the area. Although the case of printing with the adjustment parameters has been described as an example, when the same “picture” is set as the document type for both the inside and the outside of the specific area, the outside of the area is forcibly dependent on the processing result of the TI separation. It is also possible to print with the adjusted image quality adjustment parameters.

As a specific example, in a manuscript mainly composed of a halftone image, by setting a portion of a low-density pattern as a specific area, the pattern can be reproduced as a pattern image rich in gradation, while the pattern outside the specific area can be reproduced. Even if binary images such as characters are mixed in the picture image of
Since processing according to the image is performed based on the processing result of the I separation, it can be reproduced as a clear binary image.

In any case, for a document in which a binary image such as a character and a halftone image such as a photograph are mixed, a binary image region and a halftone image region are designated, and a floor is provided for each region. Even if the same image type is set inside and outside the designated area in the image forming apparatus capable of copying by specifying the tone, different image quality adjustment parameters are set inside and outside the designated area, and the setting is made. By performing image formation based on the image quality adjustment parameters, the intended purpose can be achieved.

Although the above embodiment has been described on the assumption that the identification parameter in the TI separation circuit 134 is fixed, the identification parameter can be changed between the inside of the designated area and the outside of the area. is there. In this case, the inside of the designated area is set to be determined by the user as the designated image type, and the outside of the area is set to the default TI separation parameter, that is, the normal TI separation parameter which is determined to be least erroneous. What is necessary is just to set it as the structure which processes.

According to this, processing inside the area designated by the user is performed using the TI separation parameter of the original type set by the user, and processing outside the area is performed using the normal TI separation parameter. Image formation can be performed with optimum image quality parameters both inside and outside the area.

[0056]

As described above, according to the present invention,
In an image forming apparatus capable of specifying an area for a document, setting an image type of the specified area, and outputting with different image quality adjustment parameters inside and outside the area,
Even if the same image type is set for the inside and outside of the specified area, printing is performed using different image quality adjustment parameters. Since the corresponding processing is performed, a high-quality image can be formed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a digital copying machine according to the present invention.

FIG. 2 is a diagram for explaining the relationship among the entire original, a specific area, and an area signal.

FIG. 3 is a block diagram illustrating an example of a specific configuration of a decoder.

FIG. 4 is a diagram showing a correspondence relationship between inputs and outputs of a logic RAM in a preceding stage of a decoder;

FIG. 5 is a block diagram showing a specific internal configuration of a preceding logic RAM of the decoder.

FIG. 6 is a block diagram showing a specific internal configuration of a logic RAM after a decoder.

FIG. 7 is a diagram showing an address configuration of an input of a logic RAM after a decoder.

FIG. 8 is a flowchart illustrating a procedure for setting a mode.

FIG. 9 is a configuration diagram of a UI screen in the case of mode setting.

FIG. 10 is a configuration diagram of a UI screen when an area is specified.

FIG. 11 is a flowchart illustrating a procedure for setting an image quality adjustment parameter.

FIG. 12 is a flowchart showing a procedure during a copying operation.

FIG. 13 is a diagram showing a processing concept of the present invention.

FIG. 14 is a diagram for explaining a problem of the related art.

[Explanation of symbols]

11: System control unit, 12: Document reading unit, 13: Image processing unit, 14: User interface (UI), 1
5: CCD sensor, 17: image output unit, 132: editing circuit (substrate), 134: TI separation circuit, 136: decoder, 201: preceding logic RAM, 202: subsequent logic RAM

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2C087 AA15 AA16 BA03 BA05 BB10 BC05 BD01 BD06 CA02 2H027 EB01 FD03 5B057 AA11 BA24 BA25 CA01 CA06 CA08 CA12 CA16 CB01 CB06 CB08 CB12 CB16 CE06 CE11 CE18 CH09 DB08 DB02 DC06 DB06 LL19 MP06 MP08 PP01 PP15 PP20 PP27 PP28 PP32 PP33 PP36 PP38 PQ08 SS05 TT06

Claims (8)

[Claims] 1. An image processing apparatus comprising: an area designating unit that designates an area for a document; and an image type setting unit that sets an image type of an area designated by the area designating unit. An image forming apparatus capable of outputting different image quality adjustment parameters inside and outside of an area, wherein the same image type is set by the image type setting means for the inside and outside of the area specified by the area specifying means An image forming apparatus comprising: a parameter setting unit that sets different image quality adjustment parameters for the inside and outside of the area even when the setting is performed. 2. The image forming apparatus according to claim 1, wherein the image type setting unit sets a binary image as an image type for the inside and outside of the area. 3. An identification means for identifying a binary image area and a halftone image area of a document, wherein an image type set by the image type setting means is set in an area specified by the area specifying means. 2. The image forming apparatus according to claim 1, wherein an image quality adjustment parameter is set, and the image quality adjustment parameter is changed outside the area according to a result of the identification performed by the identification unit. 4. The image forming apparatus according to claim 1, wherein the image quality adjustment parameter is a filter coefficient. 5. The image forming apparatus according to claim 1, wherein the image quality adjustment parameter is a screen coefficient. 6. The image forming apparatus according to claim 1, wherein the image quality adjustment parameter is a gradation correction curve. 7. An identification means for identifying a binary image area and a halftone image area of a document, wherein the identification means changes an identification parameter inside and outside the area. 2. The image forming apparatus according to 1. 8. The identification means sets an identification parameter so that the inside of the area is determined to be the image type set by the image type setting means, and processes the outside of the area with a default pictograph separation parameter. The image forming apparatus according to claim 7, wherein: