JPH10173912A - Image processor, image processing method, and image processing control program storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent image by suppressing image quality both at magnification and at non-magnification. SOLUTION: A reduction/magnification digital filter correction section 11 avoids filtering processing (inhibit of filtering processing) in the case that T/I discrimination data (text/image discrimination data) Tag are equivalent to a character and in the case of magnification = 100%, so as to obtain image quality with high sharpness without existence of deformed characters. Furthermore, the reduction/magnification digital filter correction section 11 conducts usual filtering processing when the T/I discrimination data Tag are an image other than a character image. As a result, a smooth image without deteriorated granularity is obtained.

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, an image processing method, and an image processing control program storage medium storing a control program for image processing. The present invention relates to an image processing apparatus such as a copier, a facsimile apparatus, and a printer that can be reduced / reduced, an image processing method of the image processing apparatus, and an image processing control program storing a control program for image processing.

[0002]

2. Description of the Related Art Conventionally, copiers, facsimile machines, printers and the like have been known as image processing apparatuses capable of enlarging / reducing characters and image portions on a document. For example, in a conventional digital copying machine, a reading unit that reads a document, an image processing unit that performs various image processing on an image read by the reading unit, and an image that is processed based on image data after image processing in the image processing unit. And an image forming unit that forms on paper.

The image processing in the image processing unit includes a scaling process. The scaling process includes a reduction process for reducing the original image and an enlargement process for expanding the original image. The reduction process is
Specifically, this is performed by thinning out pixel information indicating the density and color tone of the pixel. The enlargement process is performed by repeatedly using pixel information indicating the density and color tone of a pixel a plurality of times. In a series of copying processes including reading of an original image, image processing, and image forming processing, a certain degree of image quality deterioration due to the processing is inevitable. For example, an image is blurred due to the aberration of the optical lens at the time of reading, or moire is generated due to interference with the dither pattern.

[0004] More specifically, in the above-described conventional copying machine, as in the case of an image to be printed in a character mode (a print mode in which printing is performed on the assumption that only a character is to be printed), Hi
It is known that when an image with gh-γ and edge enhancement is formed as it is, moire is noticeable at a predetermined magnification. For example, a scaling factor = 99 [%] or a scaling factor = 101
When fine magnification adjustment such as [%] is performed, moire is noticeable in the formed image.

Therefore, in the image processing apparatus described in Japanese Patent Application Laid-Open No. Hei 5-73675, in order to reduce image deterioration due to moiré and the like, first load coefficient data for correcting image data before zooming and a variable The second load coefficient data for correcting the image data after the magnification is stored in the ROM in advance, and C
The PU calculates third weighting factor data from the first weighting factor data, the second weighting factor data, and the specified scaling factor data, and uses a digital filter to convert the image data of the target pixel and the image data of peripheral pixels of the target pixel, respectively. Image quality deterioration has been suppressed by performing a filtering process in which correction is performed with reference to a ratio determined by a matrix composed of the third weight coefficient data.

[0006]

By the way, the above-mentioned conventional filtering processing is performed at the same magnification (magnification = 100 [%]).
), Black characters are fattened in the character portion, and the characters of the obtained copy original cannot be read. More specifically, the user operates the copying machine as a character mode for copying a character document, a character / photo mode for copying a character / photo document in which characters and photos are mixed, or a user for copying a photo document. Even if the photo mode is set, since the filtering process is performed by the correction filter (LPF) after the reduction / enlargement process, as shown in FIG. 11, the characters become fat or crushed at the same magnification. I was

Therefore, if the filtering process is not performed at the same magnification and the through process is performed, the problem can be solved in the character portion, but in the image portion (picture portion), the image quality of the graininess deteriorates conspicuously. Problems have arisen. More specifically, since the filtering processing by the correction filter (LPF) is provided for the purpose of preventing the deterioration of the graininess, if this filtering processing is not performed, the graininess is poor, that is, the copied image with reduced image quality. There was a problem that it would be.

An object of the present invention is to provide an image processing apparatus, an image processing method, and an image processing control program capable of suppressing deterioration of image quality and obtaining a good image both at the time of variable magnification and at the time of equal magnification. To provide a medium.

[0009]

In order to solve the above-mentioned problems, in the image processing apparatus according to the first aspect, a scaling process is performed on image data input from the outside, and an image corresponding to the image data is converted. In an image processing apparatus capable of obtaining a scaled image, a filtering process means for performing a filtering process for image quality correction on the image data after the scaling process, and a scaling process as the scaling process are set. Processing prohibiting means for prohibiting the filtering process when the filtering is performed. The image processing apparatus according to claim 3, wherein the image processing apparatus can perform scaling processing on image data input from the outside, and obtain a scaled image obtained by scaling an image corresponding to the image data. A filtering processing unit that performs a filtering process for image quality correction on the image data after the scaling process; an image characteristic detecting unit that detects an image characteristic of an image corresponding to the image data; and the detected image characteristic And a filter coefficient setting means for setting a filter coefficient in the filtering process based on the image characteristic and a scaling factor in the scaling process when is a predetermined image characteristic set in advance.

[0010]

Preferred embodiments of the present invention will now be described with reference to the drawings. (First Embodiment) FIG. 1 shows a schematic block diagram of a main part of a copying machine according to the present embodiment. The copier is roughly divided into an image processing unit 21 that performs image processing and outputs copied image data, and an L ^* a ^* output from the image processing unit 21 to be described later ^.
b ^* Text (character) / image (picture) separation (referred to as T / I separation) is performed on the image data to determine a text area and an image area, and the determination result is output as 2-bit T / I determination data Tag. With L
^* a ^* b ^* T / I separation determination unit 22 that outputs image data as it is, and system CPU unit 16 that controls the entire copying machine
Then, the copied image data output from the image processing unit 21 is raster-scanned by a printer engine (not shown).
ROS (Raster Output Scanner) interface (I / F) unit 16 for converting the image data into raster scan copy image data and outputting the image data, and an IOT (Image Ou) not shown.
The IOT control unit 17 controls a tput terminal (printer engine) to form a copy image, and controls a console panel (not shown) for inputting various data by a user or displaying various data to the user.
/ I (User Interface) console panel control unit 19, a scan motor control unit 20 for controlling a scan motor at the time of document scanning (document scanning),
II that controls the scan motor control unit 20 in synchronization with the operations of the system CPU unit 16 and the image processing unit 21
A T (Image Input Terminal) -CPU unit 19.

The image processing section 21 receives a reading light reflected from an original (not shown) and photoelectrically converts the light into a CCD 1.
The imaging signal (analog signal) of the CD1 is converted from analog to digital to image data (BGR data; Blue, Green, R)
A / D converter 2 that outputs the data as ed data), a shading correction unit 3 that performs shading correction on the image data and outputs the first corrected image data, and performs a CCD gap correction on the first corrected image data to perform a second correction. A CCD gap correction section 4 for outputting as imaging data;
Performing gray balance correction on the second corrected imaging data,
A gray balance correcting unit 5 that outputs a third correction imaging data, performs color space conversion of the third correction captured data is BGR data, L ^* a ^* b ^* is expressed in the color space L ^* a ^* b ^*
An external interface (I / F) unit that performs an interface operation with a first color space conversion unit 6 that outputs as image data and an external interface device, a T / I separation determination unit 22, and the like under the control of an IPS-CPU unit described later. 7 and an ACS determination-T for automatically performing color / monochrome determination on L ^* a ^* b ^* image data input via the external interface unit 7 and performing text / image separation determination.
A / I separation determination unit 8, an IPS (Image Processing System) -CPU unit 9 that controls the entire image processing unit 21,
The color space conversion of the L ^* a ^* b ^* image data input via the T / I separation determination unit 22 is performed, and YMCK (Yellow,
a second color space conversion unit 10 that outputs as YMCK image data expressed as a ta, Cyan, Kuro) color space;
Reduced / enlarged YMCK image data (including the same magnification) for reducing / enlarging the image corresponding to the image data is output, and a pixel based on the T / I determination data Tag from the T / I separation determination unit 22 is output. A reduction / enlargement / digital filter correction unit 11 for performing a filtering process (digital filter correction) on a unit basis, a digital filter unit 12 for performing a filtering process on the reduction / enlargement YMCK image data for each image and outputting corrected YMCK image data, Correction YM
In the CK image data, data corresponding to the character portion is H
High-γ / Linear which performs high-γ processing and performs Linear processing on data corresponding to the image portion.
A conversion unit 13, a tone (Tone) control unit 14 for performing tone adjustment according to a gradation characteristic of an IOT (not shown),
It is provided with.

FIG. 2 shows a schematic block diagram of the reduction / enlargement / digital filter correction section 11. The reduction / enlargement / digital filter correction unit 11 receives the YMCK image data and the T / I determination data Tag and performs a filtering process on a pixel-by-pixel basis and a sub-unit based on a timing signal from an external timing generation circuit. A sub-scanning direction trimming signal generating circuit 31 for generating and outputting a scanning direction trimming signal; a first selector 32 for selectively outputting output data of the filter unit 30 to a latch circuit 33 or a multiplexer 45 to be described later; A latch circuit 33 for taking in output data of the selector 32 at a timing corresponding to the trimming signal in the sub-scanning direction, and a second selector 34 for selectively outputting either output data of the latch circuit 33 or output data of a multiplexer 45 described later. And externally applied scaling control data MAG0 to MAG1
5, a correction pattern data generation circuit 36 for generating and outputting correction coefficient data under the control of the expansion / contraction pattern generation circuit 35; Selector 3
A first and second multiplication circuit 37, 38 for multiplying and outputting the output data of No. 4; an addition circuit 39 for adding and outputting the output data of the first and second multiplication circuits 37, 38; A counter control signal generation circuit 40 for generating and outputting a counter control signal based on a timing signal from an external timing generation circuit under the control of the circuit 35; and a counter control signal based on the timing signal and the counter control signal from the external timing generation circuit. A first counter 41 that outputs first count data, a second counter 42 that outputs second count data based on a timing signal from an external timing generation circuit, and an address corresponding to the first count data, which will be described later. A first SRAM 43 for writing and reading data via the multiplexer 45; A second SRAM 44 that writes and reads data to and from an address corresponding to the second count data via a multiplexer 45 described below, and a multiplexer 45 that selectively switches and outputs various types of input data. Have been.

FIG. 3 is a circuit block diagram of the filter unit of the reduction / enlargement / digital filter correction unit 11. Reduction /
Filter unit 30 of enlargement / digital filter correction unit 11
A data latch unit 50 that latches T / I determination data Tag (2 bits) input to the data terminal D based on an external clock signal and outputs the data from the output terminal Q;
T / I output from output terminal Q of data latch unit 50
The determination data Tag is input to the select terminal SEL,
The filter coefficients A1, B1, and C1 corresponding to black characters, the filter coefficients A2, B2, and C2 corresponding to images (patterns), and the filter coefficients A3 and B3 corresponding to intermediate saturation characters according to the value of the / I determination data Tag. A selector 51 for selectively outputting any one of filter coefficients Ax, Bx, Cx (X: 1 to 4) from C3 or filter coefficients A4, B4, C4 corresponding to color characters; A first data latch unit 52 for latching the reduced / expanded YMCK image data (8 bits) input to the data terminal based on the output data and outputting the first latched reduced / expanded YMCK image data from an output terminal Q; The first latched / reduced YMCK image data output from the output terminal Q of the first data latch unit is latched based on the signal, and the second latched reduced / expanded YMCK is output from the output terminal Q. A second data latch unit 53 for outputting as image data, and a second reduced / expanded YMCK image data output from an output terminal Q of the second data latch unit 53 based on an external clock signal, and an output terminal thereof. Q, a third data latch unit 54 for outputting third latched reduced / expanded YMCK image data, and an output terminal Q of the third data latch unit based on an external clock signal.
A fourth data latch unit 55 that latches the third reduced / expanded YMCK image data output from the first unit and outputs the fourth reduced / expanded YMCK image data from its output terminal Q;
Latch contracted / enlarged YMCK image data and third latch contracted / enlarged Y
A first adding unit 56 for adding the MCK image data and outputting the first reduced / expanded YMCK image data, and a first latched / expanded YMCK image data multiplied by a filter coefficient group output by the selector 51 to obtain a first A first multiplying unit 57 that outputs multiplied image data; and a filter coefficient A that is output from the selector 51 to the first added reduced / expanded YMCK image data.
x, Bx, Cx (X: 1 to 4) to output a second multiplied image data, and a second latch reduction / expansion YM
A third multiplying unit 59 that multiplies the CK image data by the filter coefficients Ax, Bx, Cx (X: 1 to 4) output by the selector 51 to output third multiplied image data; A second adder 60 that performs a rounding process by adding the multiplied image data and the third multiplied image data and outputs the result as corrected YMCK image data.

Next, the operation of the copying machine will be described. When a user inputs a scaling ratio and a copy command via a console panel (not shown), a U / I (User Interface) console panel control unit 19 notifies the system CPU unit 16 to that effect. System CPU that was notified
The unit 16 controls the scan motor control unit 20
Control is performed via the CPU unit 19, and the scan motor control unit 20 controls the scan motor. The CCD 1 of the image processing unit 21 receives read light reflected from a document (not shown), photoelectrically converts the read light, and outputs an imaging signal to the A / D converter 2.

The A / D converter 2 converts the image signal (analog signal) from analog to digital and outputs it as image data (BGR data; Blue, Green, Red data). The shading correction unit 3 performs shading of the image data. The image data is corrected and output to the CCD gap correction unit 4 as first corrected image data. The CCD gap correction unit 4
The input first corrected image data is subjected to CCD gap correction and output as second corrected image data. The gray balance correction unit 5 performs gray balance correction on the second corrected image data, and outputs the third corrected image data. Is output to the first color space conversion unit 6. The first color space conversion unit 6 has a BGR
Color space conversion of the third corrected imaging data as data,
L ^* a ^* b ^* is expressed in the color space L ^* a ^* b ^* as image data through the external interface unit 7 ACS determination -T /
The signals are output to the I separation determination section 8 and the T / I separation determination section 22.

As a result, the ACS determination-T / I separation determination section 8 automatically performs color / black / white determination on the input L ^* a ^* b ^* image data, and also performs text / image separation determination. The / I separation determination unit 12 performs text / image separation on the input L ^* a ^* b ^* image data to determine a text area and an image area, and reduces the determination result as 2-bit T / I determination data Tag. And outputs the L ^* a ^* b ^* image data to the second color space conversion unit 10 as it is.

The second color space conversion unit 10 receives the input L ^*
Color space conversion of a ^* b ^* image data is performed, and YMCK (Yell
ow, Magenta, Cyan, Kuro) YMC expressed as color space
The image data is output to the reduction / enlargement / digital filter correction unit 11 as K image data. The reduction / enlargement / digital filter correction unit 11 outputs reduced / expanded YMCK image data (including the same magnification) for reducing / enlarging the image corresponding to the YMCK image data, and outputs a T / I separation determination unit 22
Filtering processing (digital filter correction) is performed on a pixel-by-pixel basis based on the T / I determination data Tag from.
Here, the operation of the filter unit 30 of the reduction / enlargement / digital filter correction unit 11 will be described with reference to the schematic configuration diagrams of the control system of the copying machine shown in FIGS.

In FIG. 4, the same portions as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The data latch unit 50 of the filter unit 30 latches the T / I determination data Tag (2 bits) input to the data terminal D based on an external clock signal, and outputs the latched data from the output terminal Q. The selector 51 receives the T / I determination data Tag output from the output terminal Q of the data latch unit 50 at the select terminal SEL, and according to the value of the T / I determination data Tag, filter coefficients A1 and B1 corresponding to black characters. , C1, and filter coefficients A2, B2, C corresponding to images (pictures)
2. Filter coefficients A3, B3, C3 corresponding to intermediate chroma characters
Alternatively, filter coefficients A4, B4, C4 corresponding to color characters
Any of the filter coefficients Ax, Bx, Cx
(X: 1 to 4) are selectively output.

In parallel with the operations of the data latch unit 50 and the selector 51, the first data latch unit 52 generates reduced / expanded YMCK image data (8-bit data) input to the data terminal based on an external clock signal. )
An output terminal Q outputs the first latch contracted / enlarged YMCK image data to the second data latch unit 53 and the first adder unit 56, and the second data latch unit 53 outputs the first data latch signal based on an external clock signal. Latches the first latch contracted / enlarged YMCK image data output from the output terminal Q of the unit, and outputs the second latched contracted / enlarged YMCK image data from the output terminal Q to the third data latch unit 54 and the third multiplier 5
9 is output.

The third data latch unit 54 latches the second reduced / expanded YMCK image data output from the output terminal Q of the second data latch unit 53 based on an external clock signal. Third latch contraction / expansion YMCK
The image data is output to the fourth data latch unit 55 and the first addition unit 56 as image data. The fourth data latch unit 55 outputs the third data latched from the output terminal Q of the third data latch unit based on an external clock signal. The reduced / expanded YMCK image data is latched and the fourth latched reduced / expanded YMCK is output from its output terminal Q.
The image data is output to the first multiplier 57 as image data. Accordingly, the first multiplication unit 57 multiplies the fourth latch contracted / expanded YMCK image data by the filter coefficient group output from the selector 51 and outputs the first multiplied image data to the second adding unit 60.

The first adder includes a first latch contraction / expansion YMCK.
The image data is added to the third latch contracted / expanded YMCK image data and output to the second multiplier 58 as first added contracted / expanded YMCK image data. As a result, the second multiplying unit 58 outputs the filter coefficients Ax, Bx, Cx (X: 1 to 4) output from the selector 51 to the first addition reduced / expanded YMCK image data.
And outputs the second multiplied image data to the second adder 60. The third multiplying unit 59 outputs the filter coefficient A output from the selector 51 to the second latch reduced / expanded YMCK image data.
x, Bx, and Cx (X: 1 to 4) are multiplied and the third multiplied image data is output to the second adder 60.

The second adder 60 performs a rounding process by adding the first multiplied image data, the second multiplied image data, and the third multiplied image data, and outputs the result to the digital filter 12 as corrected YMCK image data. It will be. In this case, the IPS-CPU unit 9 obtains the information of the scaling ratio set by the user through a console panel (not shown) via the system CPU unit 16 and uses the filter setting register (of the reduction / enlargement / digital filter correction unit 11). (See FIG. 5).

More specifically, for example, the actual scaling factor associated with the user setting (actual scaling factor in consideration of machine differences, etc. with respect to the scaling factor set by the user) is 100 [%] (= equal scaling factor). Yes, T / I determination data T by T / I separation determination unit 22
If ag is equivalent to the character data corresponding to the third bit B ₂ and the fourth bit B ₃ filter setting register shown in FIG. 5 to the character (e.g., B ₂ = "0", B
₃ = “0”) and the scaling factor is 100 [%].
The fifth bit B _{4 is set to} “1”. And the filter unit 3
0 indicates that the value of the filter setting register, that is, the T / I determination data Tag corresponds to a character, and the scaling ratio =
In the case of 100 [%], the filtering process is not performed (the filtering process is prohibited).
As shown in the figure, there is no character collapse, and in the character area,
It is possible to obtain an image with high sharpness.

When the value of the filter setting register and the T / I determination data Tag are images other than characters, the filter unit 30 performs a normal filtering process. As a result, in the image portion, it is possible to obtain a smooth image without deterioration in graininess. Then, the digital filter unit 12 performs a filtering process on the reduced / expanded YMCK image data in image units, and outputs the corrected YMCK image data to the High-γ / Linear conversion unit 13.

High-γ / Linear converter 13
In the corrected YMCK image data, data corresponding to a character portion is subjected to High-γ processing, data corresponding to an image portion is subjected to Linear processing, and the tone control unit 1 is provided with an IOT gradation characteristic (not shown). Is performed according to the tone. The ROS interface unit 16 converts the tone-adjusted copy image data into raster scan copy image data and outputs the raster scan copy image data to a printer engine (not shown). The IOT control unit 17 outputs an IOT (Image Output Terminal; printer engine) not shown. Is controlled to form a copy image. As a result, in the obtained copy image, it is possible to obtain a high-quality image with high sharpness in the character portion, and it is possible to obtain a smooth image in which no deterioration in graininess is observed in the image portion.

Second Embodiment In the first embodiment, the image quality is improved when the magnification is 100%, that is, when the magnification is equal.
In the second embodiment, the scaling ratio is approximately 90 [%] to 110.
In the case of [%], as shown in FIG. 10, this is an embodiment for reducing moire generated in a copied image. In the second embodiment, since the apparatus configuration of the copying machine is the same as that of the first embodiment, the apparatus configuration will be described with reference to FIG.

First, based on the judgment result of the T / I separation judgment section 22, the third bit B ₂ and the fourth bit B ₃ of the filter setting register shown in FIG. 5 are used for characters, images, intermediate chroma characters, and color characters. Set to one. For example, if the determination result of the T / I separation determination unit 22 is a character portion, the third bit B ₂ = “0” and the fourth bit B ₃ = “0”. Bit B ₂ = “1”, fourth bit B ₃ = “0”, and in the case of an intermediate chroma character portion, the third bit
Bit B ₂ = “0”, fourth bit B ₃ = 1, and in the case of a color character portion, third bit B ₂ = "1" and fourth bit B ₃ = "1".

Then, as shown in FIG.
The third filter unit 30 of the digital filter correction unit 11
The target pixel A stored in the data latch unit 54 (see FIG. 3), the target pixel B adjacent to the target pixel A stored in the second data latch unit 53 and the fourth data latch unit 55, and the first data latch The actual scaling factor associated with the user's setting for the pixel of interest C stored in the unit 52 (the actual scaling factor taking into account machine differences and the like with respect to the scaling factor set by the user)
, The filter coefficients A, B, and C are set to the following values obtained by experiments.

Actual scaling factor Filter coefficient 25 to 50% A: 0.25, B: 0.25, C: 0.25 (through setting) 51 to 90 [%] A: 0.5 B: 0.25, C: 0 (low-pass filter setting) • 91 to 99 [%] A: 0.75, B: 0.125, C: 0 (low-pass filter setting) • 100 [%] A: 0. 25, B: 0.25, C: 0.25 (through setting) 101-110 [%] A: 0.75, B: 0.125, C: 0 (low-pass filter setting) 111-200 [% A: 0.5, B: 0.25, C: 0 (low-pass filter setting) 201-400 [%] A: 0.25, B: 0.25, C: 0.25 (through setting) In this case, the through setting means that the filter unit 30
Indicates a setting that is effectively equivalent to the case where the filtering process is not performed.

Next, the filter coefficient setting operation of the copying machine according to the second embodiment will be described with reference to the processing flowchart of FIG. When a user inputs a scaling ratio and a copy command via a console panel (not shown), a U / I (User I
nterface) The console panel control section 19 notifies the system CPU section 16 of the fact (step S).
1). Thus, the system CPU 16 determines whether or not the operation mode of the input copy command is the T / I separation mode for separating and processing characters and images (step S2).

If it is determined in step S2 that the mode is the T / I separation mode (step S2; Yes), the filter coefficients A1, B1, and C1 corresponding to black characters, and the filter coefficients A2 and B2 corresponding to images (patterns). , C2, one of the filter coefficients A3, B3, C3 corresponding to the intermediate saturation character or the filter coefficients A4, B4, C4 corresponding to the color character (X: 1 to
The processing is performed using (4) (step S1).
0).

If it is determined in step S2 that the mode is not the T / I separation mode (step S2; No), the operation mode of the input copy command is a character mode (a mode in which the whole document is processed as characters). Is determined (step S3). If it is determined in step S3 that the mode is the character mode (step S3; Yes), the filter coefficient is set through (A: 0.25, B:
0.25, C: 0.25) end the process (Step S)
4).

If it is determined in step S3 that the mode is not the character mode (step S3; No), IIT (Im
age Input Terminal) Acquires the value of the same magnification adjustment (machine difference adjustment) and the value of the user magnification adjustment (adjustment in consideration of shrinkage of the copy paper due to heating during fixing) (steps S5 and S6), and obtains those values. An effective scaling factor is calculated based on and the scaling factor set in step S1, and is notified to the IPS-CPU unit 9 (step S7).

Then, the effective magnification is 100 [%],
That is, it is determined whether or not the magnification is equal (step S
8). If it is determined in step S8 that the effective scaling factor is 100%, the filter coefficient through setting (A: 0.25, B: 0.25, C: 0.25) process ends. (Step S9). If it is determined in step S8 that the effective scaling factor is other than 100%, a filter coefficient is set based on the above-described relationship between the scaling factor and the filter coefficient, and the process ends (step S1).
1).

With the above configuration, T / I
If it is determined in the separation determination that the character portion is present, the filtering process in the reduction / enlargement / digital filter correction section 11 is not performed (through setting), so that an image with high sharpness can be obtained.
When it is determined that the image portion, the intermediate saturation character portion, and the color character portion are present, an optimal filter coefficient is set according to the effective scaling factor, and the filtering process is performed. The image quality without moiré can be obtained even in the same original.

[0036]

According to the first aspect of the present invention, the filtering processing means performs filtering processing for image quality correction on the image data after the scaling processing, and the processing prohibiting means includes:
Since the filtering process is prohibited when the same-size process is set as the scaling process, unnecessary filtering process is not performed at the same-size process, and the quality of the same-size image can be improved.

According to the second aspect of the invention, in addition to the operation of the first aspect, the image data is data corresponding to a character, and the filtering process is a process using a low-pass filter. Can be suppressed, and a high-quality image can be easily obtained.

According to the third aspect of the present invention, the image characteristic detecting means detects the image characteristic of the image corresponding to the image data, and the filter coefficient setting means sets the predetermined image characteristic to the predetermined image characteristic. In the case of, the filter coefficient in the filtering process is set based on the image characteristics and the scaling factor in the scaling process, and the filtering processing unit performs filtering processing for image quality correction on the image data after the scaling process. Optimal filtering processing is performed according to the characteristics, and a high-quality image can be easily obtained.

According to the fourth aspect of the present invention, in addition to the operation of the third aspect of the present invention, the processing prohibiting means is configured to perform the effective filtering process when the scaling factor is set to a predetermined scaling factor. Since the processing is prohibited, unnecessary filtering processing is not performed according to the image characteristics, and a high-quality image can be obtained more easily.

According to the fifth aspect of the invention, in addition to the operation of the third or fourth aspect, the image characteristic is
The image has image characteristics equivalent to characters, images, intermediate saturation characters or color characters.Since the filtering process is a process using a low-pass filter, optimal filtering can be performed in accordance with the image characteristics, and high image quality without moiré Can obtain a high quality image even if the image has various image characteristics.

According to the inventions of claims 6 to 10, the same effects as those of the inventions of claims 1 to 5 can be obtained. Further, according to the inventions described in claims 11 to 15, the processing described in claims 6 to 10 can be stored in a medium and used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration block diagram of a copying machine.

FIG. 2 is a schematic configuration block diagram of a reduction / enlargement / digital filter correction unit.

FIG. 3 is a circuit configuration block diagram of a filter unit.

FIG. 4 is a schematic configuration diagram of a control system of the copying machine.

FIG. 5 is an explanatory diagram of a filter setting register.

FIG. 6 is an explanatory diagram (1) of an effect of the embodiment.

FIG. 7 is an explanatory diagram of filter coefficient assignment.

FIG. 8 is an operation processing flowchart according to the second embodiment.

FIG. 9 is an explanatory diagram (2) of the effect of the embodiment.

FIG. 10 is an explanatory diagram of a moire generation state.

FIG. 11 is an explanatory diagram of a conventional problem.

[Explanation of symbols]

 Reference Signs List 1 CCD 2 A / D converter 3 Shading correction unit 4 CCD gap correction unit 5 Gray balance correction unit 6 First color space conversion unit 7 External interface unit 8 ACS determination-T / I separation determination unit 9 IPS-CPU unit 10th Two-color space conversion unit 11 Reduction / enlargement / digital filter correction unit 12 Digital filter unit 13 High-γ / Linear conversion unit 14 Tone control unit 15 ROS interface unit 16 System CPU unit 17 IOT control unit 18 U / I console panel control unit 19 IIT-CPU section 20 Scan motor control section 21 Image processing section 22 T / I separation judgment section Tag T / I judgment data

Claims (15)

[Claims] 1. An image processing apparatus capable of performing scaling processing on image data input from the outside and obtaining a scaled image obtained by scaling an image corresponding to the image data, Filtering means for performing filtering processing for image quality correction on image data; and processing prohibition means for prohibiting the filtering processing when the same magnification processing is set as the scaling processing. Image processing device. 2. The image processing apparatus according to claim 1, wherein said image data is data corresponding to characters, and said filtering processing is processing by a low-pass filter. 3. An image processing apparatus capable of performing scaling processing on image data input from the outside to obtain a scaled image obtained by scaling an image corresponding to the image data, Filtering processing means for performing filtering processing for image quality correction on the image data; image characteristic detecting means for detecting an image characteristic of an image corresponding to the image data; and detecting the image characteristic with a predetermined image characteristic set in advance. An image processing apparatus comprising: a filter coefficient setting unit configured to set a filter coefficient in the filtering process based on the image characteristic and a scaling factor in the scaling process. 4. The image processing apparatus according to claim 3, further comprising a processing prohibition unit that prohibits an effective processing of the filtering process when the magnification is set to a predetermined magnification. Image processing apparatus. 5. The image processing apparatus according to claim 3, wherein the image characteristic is an image characteristic corresponding to a character, an image, an intermediate saturation character, or a color character. An image processing apparatus, wherein the processing is performed by a low-pass filter. 6. An image processing method capable of performing a scaling process on an image input from the outside and obtaining a scaled image obtained by scaling the image, wherein the image after the scaling process is subjected to image quality correction. An image processing method, comprising: a filtering processing step of performing the filtering processing of (1); and a processing prohibition step of prohibiting the filtering processing when the equal magnification processing is set as the scaling processing. 7. The image processing method according to claim 6, wherein the image corresponds to a character, and the filtering process is a process using a low-pass filter. 8. An image processing method capable of performing a scaling process on an image input from the outside and obtaining a scaled image obtained by scaling the image, wherein the image after the scaling process is subjected to image quality correction. A filtering processing step of performing filtering processing of: an image characteristic detecting step of detecting an image characteristic of the image; and a filter coefficient in the filtering processing when the detected image characteristic is a predetermined image characteristic. An image processing method comprising: setting a filter coefficient based on characteristics and a scaling factor in the scaling process. 9. The image processing method according to claim 8, further comprising a processing prohibition step of prohibiting an effective processing of the filtering process when the magnification is set to a predetermined magnification. Image processing method. 10. The image processing method according to claim 8, wherein the image characteristic is an image characteristic corresponding to a character, an image, an intermediate saturation character, or a color character. And a low-pass filter. 11. An image processing control program for controlling an image processing apparatus capable of performing a scaling process on image data input from the outside and obtaining a scaled image obtained by scaling an image corresponding to the image data. A filtering process for image quality correction on the image after the scaling process, and prohibiting the filtering process when the same scaling process is set as the scaling process. An image processing control program storage medium storing an image processing control program. 12. The image processing control program according to claim 11, wherein the image corresponds to a character, and the filtering process is a process using a low-pass filter. An image processing control program storage medium characterized by the above-mentioned. 13. An image processing control program for controlling an image processing apparatus capable of performing a scaling process on image data input from the outside and obtaining a scaled image obtained by scaling an image corresponding to the image data. The image processing control program storage medium according to claim 1, further comprising: performing a filtering process for image quality correction on the image after the scaling process, detecting an image characteristic of the image, and detecting the image characteristic. An image processing control program storage medium, wherein an image processing control program is stored, wherein a filter coefficient in the filtering process is set based on the image characteristics and a scaling factor in the scaling process when the image characteristics are the above. 14. The image processing control program storage medium according to claim 13, wherein when the scaling factor is set to a predetermined scaling factor, an effective processing of the filtering process is prohibited. An image processing control program storage medium characterized by being stored. 15. The image processing control program storage medium according to claim 13, wherein the image characteristic is an image characteristic in which the image corresponds to a character, an image, an intermediate saturation character, or a color character. An image processing control program storage medium storing an image processing control program, wherein the filtering process is a process using a low-pass filter.