JP2003008845A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor which prevents image-arbitrary deterioration by stably reducing radiation noise level, when image data read by a scanner, such as CCD, are processed. SOLUTION: When various image processes are performed, after the image data read by the scanner using the CCD, etc., are digitized, a frequency spread part 3 performs frequency spreading, which varies in transmission frequency continuously in specific cycles for a reference clock generated by an oscillator 2; and a timing signal generation part 4 generates a reference timing signal for image processing by the frequency spreading. The radiation noise level is therefore made reducible, and the image-arbitrary deterioration is prevented to improve the image quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly, to a radiation noise level during image processing of image data read by a scanner such as a CCD, which can be stably reduced to arbitrarily degrade an image. The present invention relates to an image processing device for preventing the above.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus for processing an image read by a scanner, a circuit using frequency spread is used for an analog signal system. When such an analog signal system circuit is used, CCD ( Charge Coupled Devic
e) When processing the output signal of a device that is driven by a digital clock signal such as a line sensor and outputs an analog signal waveform related to the phase relationship and pulse width of the clock signal, the Inability to synchronize the driving cycle of the CCD line sensor and CCD
Noise that responds to the frequency spread cycle occurs due to the output signal waveform of the CCD line sensor that slightly changes due to the influence of the frequency spread of the drive clock signal of the line sensor and the influence of the data fluctuation of the sampling position. An image may be formed in which a signal contains asynchronous noise.

That is, most of the electric components have a delay in the output signal with respect to the input signal. Generally, in a digital circuit, the clock has an edge near the center of the data in consideration of the gate delay. Is set. On the other hand, in analog signal processing, the sampling position of the analog signal that changes linearly affects the data. For example, when a feedthrough part and a data part exist in a data section of one pixel like a device such as a CCD and the levels thereof fluctuate with a linear characteristic, the data sampling is performed at the same timing. If not done, there will be a level difference in the read value.

In addition to such a problem, when frequency spreading is used for analog signal processing, frequency modulation is applied to the reference clock, so that the pulse width of the driving clock of the CCD itself also varies from pixel to pixel, and The time occupied by one pixel of the CCD output signal will also change.

Therefore, when a clock generator that generates various driving clocks from an external clock is used, the analog signal processing clocks such as the CCD driving clock and the sample hold pulse used in the analog signal processing are the same based on the reference clock. Frequency modulation will be applied in phase.

However, in practice, there are signals such as CCD output signals that have a large amount of delay with respect to the drive clock, and when processing a modulated analog signal,
It is preferable to process the modulated signals in synchronization.

However, since the conventional image processing apparatus does not consider such a point, the image quality is deteriorated due to the frequency diffusion.

Therefore, conventionally, an oscillation output means for generating a predetermined clock by frequency-spreading in which the oscillation frequency is continuously changed with respect to the reference clock is generated, and it is generated based on the reference clock. There has been proposed a clock generation device provided with a modulation reset means for resetting the frequency spreading operation of the oscillation output means according to a reference signal (see Japanese Patent Application Laid-Open No. 2000-138805).

That is, according to this prior art, the frequency spread period is reset for each line to output the noise from the main scanning to a fixed position, thereby making the variation of the noise appearing in the image a fixed position, and thus the apparent noise. Are trying to reduce.

[0010]

However, in such a conventional image processing apparatus, since the frequency spread is reset for a fixed period and asynchronously with the spread cycle, stable radiation noise is generated. There is a problem in that the level cannot be reduced and the reset of the circuit cannot be reset constantly with respect to the line period because the reset is included in the frequency spread.

Therefore, an object of the present invention is to provide an image processing apparatus capable of stably reducing the radiation noise level and preventing arbitrary deterioration of the image.

[0012] Specifically, the invention according to claim 1 is CC
When the image data read by the scanner using D or the like is digitally converted, and then various image processing is performed, the timing signal generation means continuously spreads the transmission frequency at a predetermined cycle with respect to the reference clock. And then
An image processing apparatus capable of reducing a radiation noise level, preventing arbitrary deterioration of an image, and improving image quality by generating a timing signal serving as a reference when performing image processing based on the frequency spread. Is intended to provide.

According to the second aspect of the present invention, the line period of the main scanning by the scanner is synchronized with the diffusion period to generate the timing signal, so that the period of the frequency diffusion is synchronized with the line period of the main scanning. For the purpose of providing an image processing device capable of improving the image quality by outputting noise to a fixed position from the main scanning, setting the variation of the noise appearing in the image to a fixed position, and apparently reducing the noise. There is.

According to the third aspect of the present invention, the timing signal is generated by synchronizing the main scanning line period by the scanner with the diffusion period in an integral multiple relationship, so that the frequency diffusion period and the main scanning line period are synchronized. Synchronize more properly and easily to get the noise from the main scan to a constant position,
An object of the present invention is to provide an image processing apparatus capable of improving the image quality by reducing the apparent noise by setting the variation of the noise appearing in the image at a fixed position.

According to a fourth aspect of the present invention, the generation of the timing signal is managed by the number of clocks of the clock generated by the oscillator or the like, so that the generation of the timing signal is managed easily and easily, and apparent noise is reduced. Therefore, it is an object of the present invention to provide an image processing device capable of easily and easily improving the image quality.

[0016]

According to a first aspect of the present invention, there is provided an image processing apparatus, wherein image data read by a scanner using a CCD or the like is converted into digital data and then various image processing is performed. By providing a timing signal generating unit that performs frequency spreading in which the transmission frequency continuously changes with respect to the clock at a predetermined cycle, and generates a timing signal that serves as a reference when performing the image processing based on the frequency spreading. , Achieves the above purpose.

According to the above construction, when the image data read by the scanner using the CCD or the like is digitally converted and then various kinds of image processing is performed, the timing signal generating means continuously makes a predetermined cycle with respect to the reference clock. The frequency signal with which the transmission frequency changes is generated, and the timing signal that is the reference when performing image processing is generated based on the frequency spread, so that the radiation noise level can be reduced and arbitrary deterioration of the image can be prevented. Then, the image quality can be improved.

In this case, for example, as described in claim 2, the timing signal generating means generates the timing signal by synchronizing the main scanning line period and the diffusion period by the scanner. May be.

According to the above arrangement, since the timing signal is generated by synchronizing the main scanning line period and the diffusion period by the scanner, the frequency diffusion period and the main scanning line period are synchronized to generate noise. It is possible to output the image from the main scanning to a certain position, and to make the variation of the noise appearing in the image a certain position to apparently reduce the noise and improve the image quality.

Further, for example, as described in claim 3, the timing signal generating means generates the timing signal by synchronizing the line period of the main scanning by the scanner with the diffusion period in an integral multiple relationship. It may be one that does.

According to the above configuration, since the timing signal is generated by synchronizing the main scanning line period by the scanner and the diffusion period in an integral multiple relationship, the frequency diffusion period and the main scanning line period are more appropriate. The noise can be output from the main scan to a fixed position by synchronizing easily and easily, and the variation of the noise appearing in the image can be set to a fixed position.
It is possible to reduce apparent noise and improve image quality.

Further, for example, as described in claim 4, the timing signal generating means may manage the generation of the timing signal by the number of clocks of a clock generated by an oscillator or the like.

According to the above configuration, since the generation of the timing signal is managed by the number of clocks of the clock generated by the oscillator or the like, the generation of the timing signal can be managed easily and easily, and the apparent noise is reduced. Thus, the image quality can be improved easily and easily.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and therefore have various technically preferable limitations. However, the scope of the present invention refers to the present invention particularly in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

1 to 3 are views showing an embodiment of the image processing apparatus of the present invention, and FIG. 1 shows an image processing apparatus 1 to which the embodiment of the image processing apparatus of the present invention is applied. FIG. 3 is a circuit block diagram of a main part.

In FIG. 1, an image processing apparatus 1 is an image processing apparatus that processes an analog signal and a digital signal using a clock signal whose frequency is continuously modulated, and includes an oscillator 2, a frequency spreader 3, and a timing signal generator. It includes a unit 4, an analog signal processing unit 5, an A / D converter 6, an image processing unit 7, and the like.

The oscillator 2 generates a reference clock of the image processing apparatus 1, and the timing signal generating section 4 is necessary for each section of the image processing apparatus 1 to process based on the reference clock generated by the oscillator 2. Generate timing signals. The image processing device 1 processes each image based on the timing signal generated by the timing signal generation unit 4.

The reference clock generated by the oscillator 2 is also input to the frequency spreader 3, and the frequency spreader 3 oscillates while gradually changing the frequency of the reference clock. Further, the frequency spread unit 3 outputs a spread cycle SYNC signal, and the spread cycle SYNC signal is a timing signal representing a cycle of the frequency spread processing performed by the frequency spread unit 3,
For example, the period used in a certain spread spectrum is shown in FIG.
As shown in, the signal is changing with a constant period. Further, the frequency spreader 3 period-modulates the input reference clock with a constant number of clocks CLK. For example, when A (the number of CLKs) shown in FIG. 2 is input, modulation is performed in one cycle.

The timing signal generator 4 generates a timing signal using the clock modulated by the frequency spreader 3, and the timing signals generated by the timing signal generator 4 are all frequency spread timing signals, for example,
It will be output as a clock whose frequency is spread. Therefore, the noise of the entire image processing apparatus 1 can be reduced. The frequency spreader 3 and the timing signal generator 4 function as a timing generator as a whole.

On the other hand, since the line SYNC signal is a signal generated by the scanner for each main scanning line, it is desirable that the line SYNC signal has a constant period in order for the scanner to operate at a constant speed in the sub-scanning direction. If the line SYNC signal is not constant, the driving cycle of the CCD line sensor of the scanner will not be synchronized on the time axis, noise will be generated in response to the frequency spreading cycle, and it will be asynchronous to the reference signal during image formation. An image containing noise will be formed.

Therefore, as shown in FIG. 3, the relationship between the diffusion period X of the frequency diffusion unit 3 and the period Y (line period Y) of the line SYNC signal generated once in one main scanning line will be described below. By setting as shown in equation (1), the line SY
The NC signal can be synchronized with the spread spectrum period.

Y = (a) × (X) (1) Here, a is an integer.

Then, the frequency spreading unit 3 spreads the period A
It operates to modulate one cycle with (number of CLKs),
The frequency spread can be managed by the number of clock CLKs of the reference clock generated by the oscillator 2, and the management method of the 1-line SYNC signal can also be managed by a fixed number of CLKs.
Therefore, it can be easily managed by hardware.

Further, the timing signal generating section 4 generates the timing signal to each section so as to be synchronized with the frequency spreading as described above, and the management method thereof is, for example, according to the frequency spreading cycle. Also, management is performed by the number of clocks CLK that form a cycle.

Again, in FIG. 1, the analog signal processing unit 3 uses the timing signal generated by the timing signal generating unit 4 to generate an analog image signal by a scanner using a CCD or the like, and the A / D conversion unit. Reference numeral 6 converts the analog image signal generated by the analog signal processing unit 5 into a digital image signal.

The image processing section 7 processes the digital image signal converted by the A / D conversion section 6 into an image signal suitable for an image forming apparatus which forms an image based on the digital image signal.

Next, the operation of this embodiment will be described. In the image processing apparatus 1 of the present embodiment, the oscillator 2 generates the reference clock of the image processing apparatus 1, and the frequency spreader 3 oscillates the reference clock generated by the oscillator 2 while gradually changing it. The frequency spreader 3 outputs a spread cycle SYNC signal (see FIG. 2) which is a timing signal indicating the cycle of the frequency spread processing performed by the frequency spreader 3, and the timing signal generator 4 modulates each of the frequency spreaders 3. A timing signal is generated using the clock. The timing signals generated by the timing signal generation unit 4 are all output as timing signals that are frequency spread, for example, clocks that are frequency spread. Therefore, the noise of the entire image processing apparatus 1 can be reduced.

As described above, since the line SYNC signal is a signal generated by the scanner for each main scanning line, it has a constant period for the scanner to operate at a constant speed in the sub-scanning direction. Is desirable. Also the line
If the SYNC signal is not constant, the drive cycle of the CCD line sensor of the scanner will not be synchronized on the time axis,
Noise is generated in response to the frequency spreading period, and an image in which noise that is asynchronous with the reference signal is included is formed during image formation.

Therefore, in the image processing apparatus 1 of the present embodiment, as shown in FIG.
And the synchronization of the cycle Y (line cycle Y) of the line SYNC signal that occurs once in one main scanning line,
The line SYNC signal is synchronized with the spread spectrum period by setting as shown in FIG.

Then, the frequency spreading section 3 spreads the spreading period A.
It operates to modulate one cycle with (number of CLKs),
Frequency spread can be controlled by the number of clocks CLK,
The management method of the 1-line SYNC signal can also be managed with a fixed number of CLKs. Therefore, it can be easily managed by hardware.

Further, the timing signal generator 4 generates the timing signal to each unit so as to be synchronized with the frequency spreading as described above, and the management method thereof is, for example, in accordance with the frequency spreading period. Also, management is performed by the number of clocks CLK forming a cycle.

Then, in the image processing apparatus 1, the analog signal processing section 3 uses the timing signal generated by the timing signal generating section 4 to generate an analog image signal by a scanner using a CCD or the like, and A / D The conversion unit 6 converts the analog image signal generated by the analog signal processing unit 5 into a digital image signal. The image processing unit 7 processes the digital image signal converted by the A / D conversion unit 6 into an image signal suitable for an image forming apparatus that forms an image based on the digital image signal.

Therefore, the radiation noise level can be reduced, arbitrary deterioration of the image can be prevented, and the image quality can be improved.

Further, the image processing apparatus 1 of the present embodiment is
The timing signal is generated by synchronizing the main scanning line period and the diffusion period by the scanner, for example, in the relation of an integral multiple.

Therefore, by synchronizing the frequency spreading period and the main scanning line period, noise can be output from the main scanning to a certain position, and the variation of the noise appearing in the image is made a certain position, and the apparent noise is generated. Can be reduced and the image quality can be improved.

Furthermore, the image processing apparatus 1 of the present embodiment
Manages the generation of the timing signal with the number of reference clocks generated by the oscillator 2.

Therefore, the generation of the timing signal can be managed easily and easily, the apparent noise can be reduced, and the image quality can be easily and easily improved.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

[0049]

According to the image processing apparatus of the first aspect of the present invention, the image signal read by the scanner using the CCD or the like is converted into digital data, and then various image processing is performed by the timing signal generating means. Reduces the radiated noise level by performing frequency spreading in which the transmission frequency changes continuously in a predetermined cycle with respect to the reference clock and generating a timing signal that serves as a reference when performing image processing based on the frequency spreading. Therefore, it is possible to prevent arbitrary deterioration of the image and improve the image quality.

According to the image processing apparatus of the second aspect, since the timing signal is generated by synchronizing the main scanning line period and the diffusion period by the scanner, the frequency diffusion period and the main scanning line period. Can be synchronized with each other so that noise can be output from the main scanning to a certain position, and the variation of the noise appearing in the image can be made to be a certain position to apparently reduce the noise and improve the image quality.

According to the image processing apparatus of the third aspect, the timing signal is generated by synchronizing the line period of the main scanning by the scanner with the diffusion period in an integral multiple relationship. Noise can be output from the main scanning to a fixed position by synchronizing the line period of the main scanning more appropriately and easily, and the variation of the noise appearing in the image can be fixed to reduce the apparent noise. hand,
The image quality can be improved.

According to the image processing apparatus of the fourth aspect, since the generation of the timing signal is controlled by the number of clocks of the clock generated by the oscillator or the like, the generation of the timing signal can be managed easily and easily. Therefore, it is possible to easily and easily improve the image quality by reducing the apparent noise.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a main part of an image processing apparatus to which an embodiment of an image processing apparatus of the present invention is applied.

FIG. 2 is a waveform diagram of a spreading cycle SYNC signal generated by the frequency spreading unit of FIG.

FIG. 3 is a timing diagram showing a synchronization relationship between a spreading cycle of the frequency spreading unit of FIG. 1 and a line SYNC signal.

[Explanation of symbols]

1 Image processing device 2 oscillators 3 Frequency spreader 4 Timing signal generator 5 Analog signal processor 6 A / D converter 7 Image processing unit

Claims (4)

[Claims] Claim: What is claimed is: 1. An image processing apparatus for performing various image processing after digitally converting image data read by a scanner using a CCD or the like, in which the transmission frequency continuously changes at a predetermined cycle with respect to a reference clock. An image processing apparatus comprising: a timing signal generating unit that performs frequency spreading and generates a timing signal that serves as a reference when performing the image processing based on the frequency spreading. 2. The image processing apparatus according to claim 1, wherein the timing signal generating means generates the timing signal by synchronizing a line cycle of main scanning by the scanner and a diffusion cycle. 3. The timing signal generating means generates the timing signal by synchronizing a line period of main scanning by the scanner and a diffusion period in an integral multiple relationship. Image processing device. 4. The image processing according to claim 1, wherein the timing signal generating means manages the generation of the timing signal by the number of clocks of a clock generated by an oscillator or the like. apparatus.