JP3217834B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for removing moire from a halftone image read by a CCD image sensor.

[0002]

2. Description of the Related Art Conventionally, as an image reading apparatus for removing moire of a halftone image, as disclosed in Japanese Patent Application Laid-Open No. 62-262567, for example, the position of a scanner having a photoelectric converter is mechanically adjusted. The means can be adjusted in the vertical direction, and the photoelectric converter is arranged at a position deviated from the image forming position of the optical system, so that moire is removed by a blur effect.

[0003]

However, in the above-described conventional image reading apparatus, since the photoelectric converter is mechanically arranged at a position shifted from the image forming position of the optical system, the structure becomes complicated and the structure becomes stable. There is a problem of low degree.

The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide an image reading apparatus that has a simple structure and can reliably remove moiré of a halftone dot image.

[0005]

According to a first aspect of the present invention, there is provided an image reading apparatus for reading an image with a CCD image sensor and outputting the read image to image processing means. and deleting means for outputting to said image processing means some of the pixel data by deleting randomly for each line, the deletion hand
Interpolating means for interpolating the pixel deleted by the step
And said that you are.

[0006]

[0007]

[0008]

[0009]

The second means is provided with a notifying means for notifying the image processing means of the position of the pixel deleted by the deleting means in the first means .

The third means is characterized in that the user can set whether or not the deletion means randomly deletes pixels in the first means .

The fourth means is the first means , wherein the C
The image processing apparatus further includes means for determining whether the image read by the CD image sensor is a halftone image or a photographic image. When the image is a halftone image, the deleting means randomly deletes pixels.

A fifth means is that, in the first means , when the image processing means separates a picture and a character of an image read by a CCD image sensor, the deletion means deletes pixels of the picture at random. Features.

[0014]

According to the first means, some pixels of the image data read by the CCD image sensor are deleted at random and the deleted pixels are interpolated.
Can prevent deterioration of image quality due to pixel deletion.
You.

[0015]

[0016]

[0017]

[0018]

In the second means, since the position of the deleted pixel is notified to the image processing means, it is possible to prevent the image quality from deteriorating when the deleted pixel is image-processed. The processing speed of the codec can be increased.

In the third means, since the user can set whether or not to delete pixels, it is possible to prevent the deterioration of the image quality of an image other than a halftone image by judging the type of the document. it can. In the fourth means, it is determined whether the image is a halftone image or a photographic image, and in the case of a halftone image, pixels are deleted at random, so that moiré of the halftone image can be automatically removed, and Image quality can be prevented from deteriorating.

In the fifth means, since pixels are not deleted in the case of a character, it is possible to prevent dull edges and to automatically remove moiré in a picture.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an analog signal processing circuit of an image reading apparatus according to the present invention, FIG. 2 is a timing chart showing main signals in the analog signal processing circuit of FIG. 1, and FIG. FIG. 4 is a configuration diagram showing an optical system of the apparatus, and FIG. 4 is an explanatory diagram showing output signals of the CCD sensor chip of FIGS.

First, an optical system of the image reading apparatus according to the present embodiment will be described with reference to FIG. In this apparatus, a color CCD line sensor 1 in which four CCD sensor chips 1a to 1d in which a large number of CCD elements each having a primary color filter provided in a photosensitive portion are arranged in a line is used as a photoelectric converter for reading. ing. The original 2 is a fluorescent light 3 as a light source
The reflected light is focused on the light receiving surface of the color CCD line sensor 1 by the lens array 4 and read.

Each chip 1a to 1d of the CCD sensor 1
As shown in FIG. 4, in the output period of one line, a dummy signal for 72 pixels is first output, and then an effective pixel signal for 2688 pixels is serially output. Effective pixel signals are G1, B1, R1, G2, B
The pixel signals of RGB are 896 each such as 2, R2, G3 and so on.
The pixel is output. Since the CCD sensor 1 includes four sensor chips 1a to 1d, the CCD sensor 1 outputs four signals in parallel.

Next, an analog signal processing circuit of the image reading apparatus according to the present embodiment will be described with reference to FIGS. C
Since the signal OS output from the CD sensor 1 has an offset voltage, the signal OS is clamped to 0 volt at the timing of the clamp signal CLP in the clamp circuit 10 as shown in FIG. This clamped signal Vos
The pixel is randomly deleted by a pixel signal selection signal (/ CS) (hereinafter, “/” is used for an inverted signal for convenience) in the pixel signal selection circuit 11. In addition, as a method of this deletion , for example, the same
In the pixel signal selection circuit 11, the clamp signal
If the pixel is clamped to a level higher than the white level at the timing of signal / CS , the deleted pixel becomes white and is not printed by a printer or the like without being processed by the subsequent processing circuit.

As shown in FIG. 2A, the clamp circuit 1
First, the output signal Vos of 0 is read out and randomly deleted at the timing of the pixel signal selection signal (/ CS1) in the first line to obtain a signal Vo. This signal Vo is sampled and held by the sample and hold circuit 12 by the sample clock SCLK. Obtain the signal Vs. In the second line for reading, other pixels are randomly deleted by the pixel signal selection signal (/ CS2), and in the third line for reading, other pixels are randomly deleted by the pixel signal selection signal (/ CS3). . Hereinafter, the pixel signal selection signal (/
CS) is changed for each line. The pixel signal selection signal (/ CS) can be generated by instructing a timing generator by a random number generator or the like, for example.

The signal Vs from which pixels are randomly deleted for each line is corrected in the offset removing circuit 13 so that the light shield portion (black reference portion) becomes 0 volt, and then the RGB sensitivity correcting circuit 14 By RGB
Are corrected, and the light amount fluctuation correction circuit 15 corrects the level fluctuation due to the light amount fluctuation of the fluorescent lamp 3, and
Black level correction circuit 16, shading correction circuit 17,
After various corrections are made by the black level correction circuit 18, A /
The data is converted into 8-bit digital image data by the D converter 19, for example.

Therefore, according to the above embodiment, pixels are randomly deleted for each line in the pixel signal selection circuit 11, so that moire of a halftone dot image can be reliably removed with a simple structure. Further, when the CCD sensor 1 in which the plurality of sensor chips 1a to 1d are arranged as in the above embodiment, pixels are randomly deleted for each line, and the sensor chips 1a to 1d are also used for the same line. Also, moiré can be further removed by randomly deleting pixels.

Next, a second embodiment will be described with reference to FIGS. FIG. 5 is a block diagram showing a second embodiment,
FIG. 6 is a block diagram showing a detailed configuration of the pixel signal selection circuit of FIG. 5, and FIG. 7 is a timing chart showing main signals in the second embodiment. In the first embodiment, the pixels are randomly deleted by the analog processing circuit. However, in the second embodiment, the pixels are deleted by the digital processing circuit.

The signals (channels CH1 to CH4) read by each sensor chip of the CCD sensor 1 are converted into 8-bit data by the analog processing circuit 21 to be A / D converted.
It is converted and output to digital processing circuits 22 to 27 at the subsequent stage. The data of each channel is supplied to a light amount processing circuit 22, a shading correction circuit 23, and a line delay circuit.
(B) Various corrections and parallel / serial conversion are performed by the serial conversion unit 25. Next, the RGB pixel position of each of the sensor chips 1a to 1d of the CCD sensor 1 is corrected by the RGB position correction and parallel
The R, G, and B signals are converted into B parallel signals, and the R, G, and B pixels are randomly deleted by a pixel signal selection circuit 27 as shown in detail in FIG. Note that each of the deleted RGB images is
The raw data is output to, for example, an image processing unit (IPU) and subjected to various image processing.

The pixel signal selection circuit 27 has buffers 27R, 27G, and 27B as shown in FIG. 6. Each of the buffers 27R, 27G, and 27B has a pixel selection signal (enable signal / DCS1) as shown in FIG. , / DC
S2, / DCS3), each pixel of RGB is deleted at random. In the example shown in FIG. 6, the buffer 27R,
Since the input signals of 27G and 27B are "FF" (8 bits) when the input signals are black, the output side is pulled down so that the deleted signal becomes "0" (white).

The pixel signal transfer clock V shown in FIG.
CLK is, one pixel from falling until the next falling edge of the
Minute, the enable signal (/ DCS1), (/ DCS1
2) and (/ DCS3) correspond to the controller 28 shown in FIG.
Controls the timing generator 29 so that
It changes randomly for each line, and pixels are deleted when the level is high. Therefore, also in the second embodiment, similarly, buffers 27R and 27
Since each pixel of RGB is randomly deleted for each line by G and 27B, moire of a halftone dot image can be reliably removed with a simple structure.

Next, a third embodiment will be described. FIG. 8 shows a data interpolation circuit 30 which is a main part of the third embodiment.
This circuit 30 includes a buffer 27R in the second embodiment,
27G and 27B are respectively connected to the subsequent stage. For example, in the data interpolation circuit 30 connected to the subsequent stage of the buffer 27G, the input data G (G2 is deleted) is
1 and the input data G1 and G3 are latched by the latches 32 and 33, respectively.

[0034] Then, an average value or data G2 of the data G1, G3 is calculated by the mean value circuit 34, by taking the data G and timing latched by the latch 31, the data G1, G2, as G3~ data But
Is output . Therefore, according to the third embodiment,
Since the pixels deleted by the pixel signal selection circuit 27 of the second embodiment are interpolated, it is possible to prevent the image quality from deteriorating.

Next, a fourth embodiment will be described with reference to FIG. Here, in an image forming apparatus such as a color copying machine or a color facsimile apparatus, various corrections such as γ correction, color correction, edge enhancement, pictograph separation, and the like must be performed in the image processing unit 31, but pixels are deleted. If such corrections are made to the processed data, the image may deteriorate,
Processing speed may be slow.

In the fourth embodiment, when pixels are deleted and interpolated in the digital processing circuits 22 to 27 and 30, the controller 28 notifies the image processing section 31 of the deletion position for each line. This makes it possible for the image processing unit 31 not to emphasize the pixel at the interpolation position. When the image processing unit 31 separates the picture and the character, the arrangement position of the picture and the character is notified to the controller 28 of the reading device, the character is read normally, and the pixels of the picture are randomly deleted line by line. It can be configured as follows.

Next, a fifth embodiment will be described with reference to FIGS. FIG. 10 is a block diagram showing a color facsimile apparatus using the image reading apparatus (scanner section) of the present embodiment, FIG. 11 is a block diagram showing a detailed configuration of the codec section in FIG. 10, and FIGS. FIG. 4 is an explanatory diagram showing a schematic operation of a codec section of FIG.

Operation unit 41 of this color facsimile machine
Is provided with a switch for switching between a halftone original mode and a photo original mode, and the above-described deletion and interpolation are not performed in the photo original mode. And in dot document mode, the controller scanner section 4 2, and go only deletion described above,
The read data is stored in the image memory 4 by performing both deletion and interpolation.
3. It is configured to transmit to the codec section 44. Therefore, when the user determines the type of the image of the read original, it is possible to prevent the image quality from deteriorating when reading an image other than the halftone image.

It is also possible to automatically switch between the halftone original mode and the photo original mode. This operation will be described in detail. At the time of transmission, when the system controller 45 detects a transmission instruction via the operation unit 41, the system controller 45 activates the scanner unit 42, and the scanner unit 42 starts reading an image and stores the RGB data in 8 units. Read in bits. Further, the system controller unit 45 includes the codec 4
4, the coding unit 44 instructs the start of coding, and the codec unit 44 fetches image data from the scanner unit 42 and performs coding, as shown in FIG.

As shown in FIG. 11, the codec 44 includes a CPU 51, a DMA controller 52, a bus interface 53, an image memory 54, a digital signal processor (DSP) 55 for encoding, and a FIFO.
An O memory 56 and the like are provided.

The data encoded by the codec section 44 is sent to the system controller section 45 and temporarily stored in the storage device 46. Then, the system controller section 45 activates the ISDNI / F section 47 to activate the encoded data. Is transferred to the other party via the line, and the ISDN I / F unit 47 notifies the system controller unit 45 of the completion of this transfer. The system controller 45 sends the operation end 41 and the CRTI / F 4
8. Display the transfer end on the CRT 49 and return to the standby state.

In this transmission, when the codec unit 44 takes in the image data from the scanner unit 42 and performs encoding, the codec unit 44 determines whether or not the image is a halftone image based on a high frequency component of DCT (discrete cosine transform). By notifying the controller of the scanner unit 42 in the case of an image, only the above-described deletion is performed, or both the deletion and the interpolation are performed. Further, when transmitting a document in which a halftone image and a photographic image are mixed, the codec unit 44 determines only the halftone image and performs only the above-described deletion, or performs both the deletion and the interpolation. May be.

[0043]

As described above, according to the first aspect of the present invention, there is provided an image reading apparatus for reading an image with a CCD image sensor and outputting the image to image processing means.
And deleting means for outputting to said image processing means some of the pixels of the image data read by the D image sensor to remove random for each line, remove by the deletion unit
Notification means for notifying the image processing means of the position of the pixel
With steps , it is possible to process deleted pixels when performing image processing.
Image quality can be prevented from deteriorating, and facsimile
Can increase the processing speed of the codec in the device.
Wear.

[0044]

[0045]

[0046]

[0047]

[0048] According to a second aspect of the invention, since with a notifying means for notifying the positions of the pixels that have been deleted by said deleting means in the invention according to the first SL mounting to the image processing means, image pixels that have been removed It is possible to prevent the image quality from deteriorating during processing, and to increase the processing speed of the codec in the facsimile apparatus.

According to a third aspect of the present invention, in the first aspect of the present invention, the user can set whether or not the deletion means randomly deletes pixels. It is possible to prevent the image quality of an image other than the halftone image from deteriorating.

According to a fourth aspect of the present invention, in the first aspect of the present invention, there is provided means for determining whether an image read by the CCD image sensor is a halftone image or a photographic image,
In the case of a halftone dot image, the deletion means randomly deletes pixels, so that moiré of the halftone dot image can be automatically removed and deterioration of the image quality of the photographic image can be prevented.

According to a fifth aspect of the present invention, in the first aspect of the present invention, when the image processing means separates a picture and a character of the image read by the CCD image sensor, the deletion means randomly selects pixels of the picture. Since deletion is performed, pixels are not deleted in the case of a character, so that dull edges can be prevented, and moiré of a picture can be automatically removed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of an analog signal processing circuit of an image reading apparatus according to the present invention.

FIG. 2 is a timing chart showing main signals in the analog signal processing circuit of FIG. 1;

FIG. 3 is a configuration diagram illustrating an optical system of the image reading apparatus of FIG. 1;

FIG. 4 is an explanatory diagram showing output signals of the CCD sensor chip of FIGS. 1 and 3;

FIG. 5 is a block diagram showing a second embodiment.

FIG. 6 is a block diagram illustrating a detailed configuration of a pixel signal selection circuit in FIG. 5;

FIG. 7 is a timing chart showing main signals in the second embodiment.

FIG. 8 is a block diagram showing a data interpolation circuit which is a main part of the third embodiment.

FIG. 9 is a block diagram showing a fourth embodiment.

FIG. 10 is a block diagram illustrating a color facsimile apparatus using the image reading apparatus according to the present embodiment.

FIG. 11 is a block diagram illustrating a detailed configuration of a codec unit in FIG. 10;

FIG. 12 is an explanatory diagram illustrating a schematic operation of the codec unit in FIGS. 10 and 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CCD image sensor 1a-1d Sensor chip 11, 27 Pixel signal selection circuit 30 Pixel data interpolation circuit 31 Image processing part 44 Codec part

Claims (5)

(57) [Claims] 1. An image reading apparatus for reading an image by a CCD image sensor and outputting the read image to image processing means, wherein some pixels of the image data read by the CCD image sensor are randomly deleted for each line. Deletion means for outputting to the image processing means, and interpolation means for interpolating the pixels deleted by the deletion means
Image reading apparatus characterized in that it comprises, when. 2. The position of a pixel deleted by said deleting means.
The image reading apparatus according to claim 1 , further comprising a notifying unit that notifies the image processing unit of a position . 3. The method according to claim 2, wherein said deleting means deletes pixels randomly.
Setting means for the user to set whether or not
The image reading device according to claim 1, wherein: 4. A reading by the CCD image sensor.
Means to determine whether the received image is a halftone image or a photographic image.
In the case of a halftone image, the deletion means randomly selects pixels.
2. The image reading device according to claim 1 , wherein the image reading device deletes the image. 5. The image processing means according to claim 1, wherein said image processing means is a CCD image sensor.
If you want to separate the picture and text of the image read by
It is characterized in that the deleting means deletes picture pixels at random.
The image reading device according to claim 1, wherein