JPH06217130A - Image processor - Google Patents

Abstract

PURPOSE:To accurately detect a specified infrared color in an original by resolving the color of an infrared area with the two kinds of wavelengths at least and comparing it with a fixed value. CONSTITUTION:A comparator 50 compares a previously decided constant K1 with an IR sensor output IR1 at 800nm and when reflected light is less than the constant K1, namely, when ink is absorbed, '1' is outputted to an AND circuit 53. On the other hand, a divider 51 calculates the ratio of IR sensor output IR2/IR1 at the other wavelength and compares the ratio with a constant K2 larger than '1' by a comparator 52 and when it is larger, '1' is outputted to the circuit 53. When the output of the circuit 53 is the final decided result and this is '1', the characteristic of ink is detected and at such a time, image processing control such as painting it out in black while including the already recorded image or stopping recording is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine, an image reading scanner, a facsimile, etc., and particularly to an image for reading an image as a digital signal, identifying a specific feature in the image, and controlling the subsequent image processing. Regarding a processing device.

[0002]

2. Description of the Related Art It is known to detect and identify visible patterns and features of visible images for the purpose of preventing counterfeiting of securities.

[0003]

Since the patterns and characteristics are visible, it is difficult to make the patterns common to all securities and the like so that they can be easily detected by a copying machine or the like.

It is also easy to make a characteristic of the feature so as to bypass the forgery prevention function from the detection algorithm.

On the other hand, in order to achieve the same function with a non-visible pattern such as a pattern detected by infrared light, for example, in the case of a color copying machine, it is difficult to focus an image from the visible region to the infrared region. .

The present invention solves the above-mentioned drawbacks of the prior art,
The purpose is to realize a highly accurate recognition function with a simple configuration based on information other than visible information.

[0007]

In order to solve the above problems, the present invention solves the above-mentioned problems by image reading means for color-separating the infrared region with at least two kinds of wavelengths, and means for comparing an output signal of the reading means with a predetermined value. By providing the above, the specific infrared color in the original can be detected with a simple structure and with high accuracy.

[0008]

<Example 1> It is known that ink used in ordinary printing reflects light in the infrared region.
However, for example, the SIR-1 of Mitsui Toatsu Chemicals shown in FIG.
Like No. 59, there is a coloring material that is almost transparent in the visible region and exhibits a sharp absorption characteristic in the infrared region. A technique of printing using a coloring material that looks like the same color in the visible region and reflects or absorbs in the infrared region is conceivable.

That is, in the pattern of FIG. 2, both the AB region in the visible region can be seen in the same color (visible), but if the infrared absorption can be detected in the B region, the invisible pattern can be identified. For example, it is possible to make this AB pattern a common pattern for all securities by printing the area A as the ground color part (area not printed) of securities and printing the area B with the transparent ink of FIG. it can.

However, considering the wavelength characteristics of FIG. 1, it is not possible to detect only one specific wavelength and distinguish it from infrared absorption by a specific pattern. That is, a commonly used coloring material such as carbon black exhibits absorption characteristics in a wide band including the wavelength absorbed by the transparent ink. Therefore, it is not possible to identify whether the ink is transparent ink or carbon black by simply inspecting the absorption characteristic of only one wavelength.

Therefore, the present invention solves this problem by the following configuration.

An embodiment of the present invention will be described with reference to the block diagram of FIG. FIG. 3 is a block diagram of a color copying machine, in which the image reading sensor 1 is an R sensor for reading visible information of a document.
The sensor cell has a color separation filter of (red), G (green), and B (blue), and a sensor cell having an infrared filter for reading a specific pattern as infrared information. The IR output is input to the determination unit 5, which is a feature of the present invention, to determine whether the securities are securities. on the other hand,
The RGB visible image information is received by the general color image processing unit 2,
C (cyan), M (magenta), Y (yellow), K
It is converted into a (black) recording signal and output to the recording control unit 3. In the recording control unit 3, when it is determined by the determination unit 5 that the document is a specific document such as securities, for example, the image including the already recorded image is blackened or the recording is stopped. Image processing is controlled, and recording is executed by the recording unit 4.

The image reading sensor 1 is composed of two cell groups as shown in FIG.
GB stripe filters are sequentially configured,
Serial visible information is output.

On the other hand, the line 11 has the same pixel IR ₁ ,
It outputs an infrared component separated into two types of wavelength components different from IR ₂ . That is, the IR ₁ output centered around λ ₁ = 800 nm, which exhibits the most absorption characteristics of the ink in FIG. 1, and the IR ₂ output centered around λ ₂ = 900 nm, which exhibits the reflection characteristic again.

The feature of the present invention resides in that the infrared characteristic is detected by at least two wavelength components and the infrared characteristic of the ink to be judged is specified.

That is, it cannot be judged as carbon black or the like only by confirming infrared absorption only by IR _1, but if infrared reflection is confirmed by IR ₂ , it is recorded with a transparent ink for preventing forgery. Can be recognized.

That is,

[0018]

[Outer 1] In case of, it is judged as a specific manuscript such as securities.

Here, the reason why the ratio of IR ₂ / IR ₁ is used as a judgment scale is that it takes into consideration that the reflectance is lowered as a whole due to dirt and the like.

FIG. 5 shows an embodiment of the judging section 5 for carrying out the above judgment. The comparator 50 uses a predetermined constant K ₁
And the IR sensor output IR ₁ at 800 nm are compared, and when the reflected light is smaller than the constant K ₁ , that is, when the ink is absorbed, 1 is output to the AND circuit 53. On the other hand, the divider 51 obtains a ratio of IR ₂ / IR _1, the results were compared with the constant K ₂ by the comparator 52 (K _2> 1), and outputs 1 to the AND circuit 53 if the K ₂ or more .

The output of the AND circuit is the final determination result, and when it is "1", the characteristics of the ink in FIG. 1 are detected.

Second Embodiment Further, in order to accurately detect the infrared characteristics of the ink, the spectral output IR ₃ at λ ₃ = 1000 nm may be obtained.

That is,

[0024]

[Outside 2] When the condition (here, K ₂ > 1 K ₃ > K ₂ ) is satisfied, it is assumed that there is a specific pattern formed by the transparent ink.

<Embodiment 3> In this embodiment, in order to detect more accurately, λ ₄ ≈700, λ ₁ ≈800, and λ ₂ ≈90.
The output value is set to 0, so-called masking processing is performed on each output value using the mutual values, and the profiles of the detection filters of IR ₄ , IR ₁ , and IR ₂ are also corrected.

IR ′ ₄ = a ₁₁ IR ₄ + a ₁₂ IR ₁ + a ₁₃ IR ₂ · IR ′ ₁ = a ₂₁ IR ₄ + a ₂₂ IR ₁ + a ₂₃ IR ₂ · IR ′ ₂ = a ₃₁ IR ₄ + a ₃₂ IR ₁ + A ₃₃ IR ₂ (a _{11 to} a ₃₃ are coefficients) Further, IR ′ ₁ is I
R a _'4, IR' ₂ normalized,

[0027]

[Outside 3] When, it is assumed that there is a specific pattern.

FIG. 6 shows an example of the configuration for implementing the above-mentioned determination algorithm. The masking circuit composed of a multiplier and an adder is a sensor output value which is spectrally separated by filters having center wavelengths of 700 nm, 800 nm and 900 nm, and the correction calculation of the above equation is performed using the data of the coefficient memory 55.

Among the results, IR ' ₄ and IR' ₂ are output values obtained by normalizing with IR ' ₁ in dividers 56 and 57.

[0030]

[Outside 4] Is input to the determination ROM 58. The ROM 58 is a so-called LUT (look-up table), and the determination result is written in advance based on l ₁ to l ₄ in the above equation.

That is, by normalizing with IR ' _1, it is possible to determine the infrared absorption characteristics by removing the influence of dirt.

<Other Embodiments> In the description, the judgment is made at one point for each pixel, but the input infrared image data may be calculated as the average value of a plurality of pixels, or conversely, the judgment result for each point. The final determination may be made based on the fact that a predetermined number has been accumulated.

According to the above embodiment, since pattern matching is not used, it is possible to make a determination in the infrared region without the need for focusing. Since there are few processing operations, the device can be realized at low cost. Since the pattern matching is not used, it is not necessary to allocate the sensor cells to the same pixel by IR, IR ₂ , and IR ₃ , and it is not necessary to correct the deviation of the reading position of the sensor, and the device can be constructed at low cost. Also, it is not necessary to consider the relationship between the pattern size and the resolution of the sensor.

[0034]

As described above, according to the present invention, a highly accurate recognition function can be realized with a simple structure based on information other than visible information.

[Brief description of drawings]

FIG. 1 is a diagram showing reflectance characteristics of transparent ink used in an example of the present invention.

FIG. 2 is a diagram showing a pattern formed by transparent ink used in an example of the present invention.

FIG. 3 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a sensor according to an embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a determination unit 5 according to the embodiment of this invention.

FIG. 6 is a diagram showing another configuration example of the determination unit 5 according to the embodiment of the present invention.

[Explanation of symbols]

 50 Comparator 51 Divider 52 Comparator

Claims (2)

[Claims] 1. An infrared image is detected, comprising image reading means for color-separating an infrared region with at least two kinds of wavelengths, and means for comparing an output signal of the reading means with a preset reference value. An image processing device characterized by: 2. The image processing apparatus according to claim 1, further comprising means for correcting the color separation signals by mutually using the plurality of color separation signals.