JPH0319570A - Picture processing unit - Google Patents

Abstract

PURPOSE:To attain highly accurate picture read and picture processing by moving a lens system of part of an image forming optical system onto an optical axis in response to the arrangement pitch of photodetectors of a picture detection means with an adjustment means so as to adjust the image forming state of picture information formed on the face of the picture detection means. CONSTITUTION:When a spatial frequency of picture information of an original 1 is higher than a spatial frequency of an arrangement pitch of a photodetector of a picture detection means 6, so-called sampling frequency, each component is set so that the spatial frequency component over the sampling frequency component is nearly 10% or less. Based on the information from a control means 22, an adjustment means 23 moves the image forming optical system 5 on the optical axis to defocus the picture information formed on the face of the picture detection means 6 and each component is set so that the spatial frequency component over the sampling frequency component is nearly 10% or less. Thus, production of moire is prevented in an excellent way to improve the edge emphasis and resolution of characters and to attain highly accurate picture reading and picture processing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image processing device, and more particularly, to an image processing device that uses an imaging optical system to transfer image information on the surface of a document onto the surface of an image detection means such as a CCD comprising a plurality of light receiving elements. This invention relates to an image processing device that prevents the occurrence of distortion when forming, reading, and subsequently performing digital processing, and enables highly accurate image reading and image processing. (Prior Art) Conventionally, in devices such as facsimile machines and digital copying machines, image information is captured using imaging optical systems such as CCI (solid-state image sensor), etc. The image detection means is formed on the surface of the image detection means consisting of 3i light receiving elements, and the image information is read.When using the image detection means in which Wi number of light receiving elements are arranged at a predetermined pitch in this way, ldii@ Moiré may occur in the output signal from the image detection means depending on the spatial frequency contained in the information. Various methods have been proposed to remove moiré. For example, there is a method in which an image is read while vibrating the detection means, a method in Japanese Patent Application Laid-Open No. 83-79470 uses at least two or more detection means such as solid-state image sensors with different sampling frequencies, and A method has been proposed that uses a smoothing circuit to form image information by defocusing it at a predetermined position on the surface of the detection means. (Problem to be solved by the invention) However, among the above-mentioned methods, the method of vibrating the detection means is mechanical! l! ! There is a problem that the Hl structure and timing are difficult, and JP-A-63-79470
The method proposed in the publication uses at least two detection means with different sampling frequencies to perform reading, and for example, for each orthogonal transform component, the one with the smaller absolute value is used as an output signal. In order to use more than this, a larger number of mesoris are required, and the entire device becomes larger. Jif
There was a problem that the technology was becoming more and more advanced and ambitious. Another problem with the method of blurring the image information after sampling through a smoothing filter is that lines and characters other than the fringes are also blurred. In the present invention, when image information is formed on the surface of an image detection means consisting of a plurality of light receiving elements arranged at a predetermined pitch, an adjustment means is provided to control the imaging optical system according to the spatial frequency components included in the ldij image information. The purpose of this invention is to provide an image processing device that performs highly detailed image reading and image processing by moving at least six parts of the lens system along the optical axis to change the imaging state. (Means for Solving the Problems) The FI image processing device of the present invention forms and reads image information on an image detecting means surface consisting of a plurality of light receiving elements arranged at a predetermined pitch using an imaging optical system. After AD converting the output signal from the image detection means to obtain a digital signal, the result is processed in an image processing device that performs predetermined image processing using image processing means such as masking and OCR, and outputs the result from the output T-stage. The imaging state of the image information formed on the image detecting means surface L by moving at least a part of the lens system of the image optical system on the optical axis according to the arrangement bit of the light receiving elements of both the image detecting means by the adjusting means. It is characterized by being able to adjust the C Embodiment) FIG. 1(A) is a schematic diagram of the main part of the image detection section of the image processing device of the present invention, and FIG. 1(B) is a block diagram of one embodiment of the image processing device of the present invention. be. In FIGS. 1(A) and 1(B), l denotes an original document placed on two sides of the original platen glass. Reference numeral 2l denotes an image detecting means, which is configured to be movable in the direction of the arrow 21a, and scans and reads the image information on one side of the original. The image reading means 2l illuminates the original 1 with the light beam from the light source 3, and after reflecting the light beam from the R light source 3 with the mirror 4,
A plurality of light receiving elements are formed by an imaging optical system 5 on a surface of an image detecting means 6 such as a CCD arranged at a predetermined pitch. 22 is II+ control means, and the output from the image detection stage 2I {as described later based on No. 8! ! At least a part of the lens group of the imaging optical system 5 is aligned with the optical axis through the alignment stage 23.
Fl is moved to adjust the convergence state of the image information formed on the image detection hand PiB surface-E. FIG. 1 (Bl shows that the image copying information of the original l is imaged on the image detection f-stage 6 surface by the imaging optical system 5, and the output signal from the image detection F-stage 6 is passed through the shading correction circuit 7. The A/D RM!1 circuit 8 converts the image into digital f3 and inputs it to the image processing system 9. After performing the prescribed image processing in the image processing system 9, 2-pixel smoothing is performed in the F clearing circuit 1O, and the edge Emphasis circuit 1
．． 1 to make characters etc. clearer. The output means 12 also sends the signal-processed digital image information to, for example, a digital copying machine (not shown). Generally, the spatial frequency of the image information of the original l is 6,000 steps for image detection.
When the spatial frequency of the arrangement pitch of the light receiving tags is 6 higher than the so-called sampling frequency, moiré occurs. Therefore, in Honjitsu IMN, when the spatial frequency component of the input image 'RH41 is higher than the sampling frequency, each element is set so that the spatial frequency component higher than the sampling frequency component is about 10% or less. That is, for the sampling interval d of the light receiving element of the image detecting means 6, the MTF of the imaging optical system {a(Mad −u I a
t. io n'I- r a n s f
By making the spatial frequency component 1/d or higher equal to 10% or more, the spatial frequency component of the human-powered image of Haraaki 1 is equal to or higher than the sampling frequency by -1, so that no moiré occurs. That's what I do. In this embodiment, the A adjustment 'f' is based on the information from the control means 22.
This is done by moving the imaging optical system 5 on the optical axis using the -stage 23 and defocusing the rain image information formed on the image detection T-stage 6 surface. In addition, in this embodiment, when the sampling frequency is determined in advance, the lens configuration of the imaging optical system may be set accordingly, or a low-pass filter or the like may be used.
FIG. 2(A) is an explanatory diagram showing the relationship between the MTF value and the spatial frequency component of the imaging optical system according to the present invention, and FIG. 2(B) is a sampling interval of the light receiving element of the image detecting means according to the present invention. It is an explanatory diagram showing d, the alignment direction, and the size. As shown in the figure, the sampling frequency of the image detection means is 1.
At 7d or more, the MTF of the imaging optical system is 10% or more F.
It is adjusted so that FIG. 3(A) is an explanatory diagram showing the sensitivity distribution when the sensitivity of one light receiving element of the direct image detection means is set to 10. Generally, the frequency characteristics of a photodetector in the spatial frequency plane can be analyzed using orthogonal function transformation. For example, Fourier transform is used as this orthogonal transform. Now, if the distribution function of the light-receiving element is c (xl), the function after transformation is C(ν)=f ic (x)l, which can be obtained as the f-Fourier transform symbol. Figure 3 (B) shows C at this time. (ν). Here, although there are negative values in the values after Fourier transform, there is actually no negative region, so the absolute value in Figure 3 (B) is used as the MTF value. Figure 4 shows the circumference IIl number characteristic of the light receiving element when the sampling interval of the light receiving element and the aperture size of the light receiving element r are the same as C(ν
], and the spatial frequency component of the imaging optical system is expressed as ]1(ν
). In this embodiment, based on such analysis, the MTFvI of the imaging optical system is set to be 10% or less than the sampling frequency component of the light-receiving tag, thereby effectively preventing the occurrence of moiré when reading image information. +1
-I'm seeing it. (Effect of fe brightness) According to the present invention, each error is reduced so that the M T "F value of the viscoimage optical system becomes 10% or less at the sampling frequency of 1/d to 11 of the light receiving element of the image detection F stage. By setting this, it is possible to effectively prevent the occurrence of such distortion and improve edge emphasis and character resolution, making it possible to achieve an image processing device that can perform highly accurate southern image reading and image processing.

[Brief explanation of the drawing]

Figures 1 (A) and (B) are an explanatory diagram and a block diagram of a two-image detection unit according to an embodiment of the present invention, respectively, and Figures 2 (A) and ([3]
is a schematic diagram of the MTF value of the imaging optical system and the light-receiving tree of the image detection means, Figures 3 (A) and (B) are explanatory diagrams of the sensitivity and aperture of the light-receiving element after Fourier transformation, and Figure 4 is the light-receiving element. FIG. 2 is an explanatory diagram of the sampling frequency of , and M'r fill of the imaging optical system. In the figure, 1 is a document 32, which is a document table glass, 3 is a statement light source, 4 is a mirror, 5 is an imaging optical system, 6 is a detection means,
21 is an image detection means, 22 is an Il1 control means, 23 is;
l# adjustment means.

Claims (1)

[Claims] (1) Image information is formed and read by an imaging optical system on the surface of an image detecting means consisting of a plurality of light receiving elements arranged at a predetermined pitch, and the output signal from the image detecting means is AD converted and converted into a digital signal. In the image processing apparatus, the image processing means performs predetermined image processing and outputs the image from the output means. An image processing apparatus characterized in that the imaging state of the image information formed on the surface of the image detecting means is adjusted by moving the image information on the optical axis according to the arrangement pitch of the image detecting means.