JPH04185077A - Image reader - Google Patents

Abstract

PURPOSE:To obtain clear image output by preparing the optimum gamma correction curve corresponding to several kinds of card from white to black and selecting the optimum gamma correction curve suitable for respective cards. CONSTITUTION:The density of an optical image of a cashing card 100 is digital- converted to be supplied to a frame memory 107 and a density detection part 108. The density detection part 108 accumulates and adds a digital signal to detect the average density of the cashing card 100, and a gamma correction curve selection part 109 outputs a control signal selecting the optimum gamma correction curve according to the average density to the gamma correction circuit 110. In the gammacorrection circuit 110, the optimum gamma correction curves suitable for from white to black cards are preliminarily prepared, and the gamma correction curve suitable for the card is selected. Thus, the clear image output for each card can be obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is an automatic transaction device (A
This invention relates to an image reading device for cashing cards and the like in TM).

(Conventional technology) Generally, ATMs and C
In D, a card with a magnetic stripe called a cash advance card is used to verify the identity of the customer at the time of withdrawal.

When a customer uses this card to operate an ATM, etc., based on the information stored on the card's magnetic stripe, the device performs the customer's desired transaction, i.e., deposits, deposits, etc.
Withdrawals, transfers, etc. will be made.

At that time, in addition to the transaction, we print the Enmes character area with information such as the account number and name on the cashing card and provide the customer with a copy of the card as a statement of transaction.
Financial institutions keep these coins as proof of transactions. Generally, the printing of these Endless characters used a pressure-sensitive method in which a pressure-sensitive paper was placed on the Endless characters and a roller or the like was pressed against the pressure-sensitive paper. As a result, the mainstream is to use an image reading device that prints out this data using a printer.

FIG. 2 shows a configuration diagram of a conventional image reading device. In the diagram, 200 is a cashing card, 20
1 is a light source such as an LED array that illuminates the card; 202 is a convergent rod lens array; 203 is a one-dimensional image sensor; 204 is a sensor drive unit; 205 is an amplifier circuit;
206 is an analog/digital conversion circuit (hereinafter referred to as an A/D conversion circuit); 207 is an r (gamma) correction circuit;
08 is a binarization processing section, and 209 is a printing section. Also, A
210 is a white level setting circuit connected to the /D conversion circuit 206, and 211 is a black level setting circuit.

When the card 200 is conveyed by some means in the direction of the arrow 212 and comes under the image sensor 203, the light source 201
The card is irradiated with the irradiation light from the card, and the reflected light from the card is imaged on the image sensor 203 via the rod lens array 202, and photoelectric conversion is performed under the control of the sensor drive unit 204.

The photoelectrically converted reading signal is amplified to a predetermined level by an amplifier circuit 205, and then sent to the next stage A/D conversion circuit 206.
supplied to In this A/D conversion circuit 206, -
The amplified reading signal (analog signal) is determined based on the relationship between the black and white reference voltages supplied from the white level setting circuit 210 and the black level setting circuit 211, for example, 8 pixels per pixel).
The digital signal is converted into a digital signal representing multi-level density (256 gradations), and is supplied to the r correction circuit 207 at the next stage.

This r correction circuit is a circuit for electrically correcting the difference in density balance between the print quality of the cashing card body used for reading and the quality of the print image obtained from the above-mentioned image reading device. It is.

A generally used r correction circuit uses a look-up table in an arithmetic ROM as shown in FIG. Correction processing is performed based on an r correction curve fixed to the device.

The r correction curve is a graph of the relationship between the output gradation level and the input gradation level of the arithmetic ROM.

In other words, a multi-signal reading with 8 pits per pixel (256 gradations) is input into the calculation ROM, and the corresponding output signal is a signal with 6 pits per pixel (64 gradations). Perform r correction processing at the expense of the number of gradations when converting to
Processing is performed so that the print image quality output from the printer comes closest to the print quality of the cashing card body used for reading.

The r-corrected signal is subjected to pseudo gradation processing, such as dither processing, error diffusion processing, etc., in the next-stage binarization processing unit 208, and then to the printing unit 209, for example, thermal It is printed by a printer using a recording method and used as an image output for the card.

(Problem to be solved by the invention) However, in recent years, cash cards used in financial institutions have started to come in a wide variety of designs, such as whitish cards and dark cards. Although the conventional image gun system can produce satisfactory image output for cards of the -m class, it is difficult to obtain clear image output for all other types of cards. A problem is occurring.

In other words, even if relatively good image quality can be obtained for medium-density design cards and cards, sufficient contrast cannot be obtained for whitish or dark cards. When reading a card, there was a problem with the dark areas of the print being crushed, and when using a card that was mainly white, there were problems such as the image of the white area appearing white (the printed output appeared blown out). .

SUMMARY OF THE INVENTION An object of the present invention is to provide an image shooting device that solves these conventional problems and makes it possible to obtain clear image output for a wide variety of design cards.

(Means for Solving the Problems) In order to solve the above problems, an image reading device according to the present invention photoelectrically converts an optical image of a medium to be read, such as a cash advance card, and further converts an optical image of a medium to be read, such as a cash advance card, into a digital image that represents a multi-value density. - means for converting into a zotal signal; a frame memory for storing the digital signal; a density detection means for detecting the average density over the entire surface of the read medium based on the digital signal; γ correction curve selection means that outputs a control signal for selecting an optimal γ correction curve according to the reading medium; The present invention is characterized by comprising a γ correction means for performing correction processing on the signal using a selected γ correction curve.

At this time, it is preferable that the density detection means is configured to detect the average density of the medium to be read by cumulatively adding the digital signals.

(Operation) In the image reading device configured as above,
The optical image of the medium to be read is photoelectrically converted and further converted into a digital signal representing multi-level density, which is then stored in a frame memory and also supplied to the density detection means. The density detection means detects the average density of the medium to be read by cumulatively adding the digital signals, and the γ correction curve selection means controls to select an optimal γ correction curve according to the detected average density. The signal is output to the γ correction means.

The γ correction means has several types of optimal γ correction curves corresponding to several types of cards, from whitish cards to dark cards, prepared in advance.The control signal selects the optimal γ correction curve suitable for the card. , optimal r correction processing is performed on the digital signal stored in the frame memory.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram of an embodiment of an image reading device according to the present invention. In the figure, 100 is a cash card as a medium to be read, and 101 is an LED that illuminates the card.
a light source such as an array; 102 is a convergent rod lens array;
103 is a one-dimensional image sensor, 104 is a sensor drive unit, 105 is an amplifier circuit, 106 is an A/D conversion circuit, 10
2 is a frame memory, 108 is a density detection unit, and 109 is γ.
A correction curve selection section, 110 is a γ correction circuit, 11 is a binarization processing section, and 112 is a printing section. Further, 113 connected to the 0 conversion circuit is a white level setting circuit, and 114 is a black level setting circuit. When the card 100 is conveyed by some means in the direction of the arrow 115 and comes under the image sensor 103, the light source The card is irradiated with light from the rod lens array 101, and the light reflected from the card is reflected from the rod lens array 102.
An image is formed on the image sensor 10g via the image sensor 10g. The imaged reflected light is photoelectrically converted in the image sensor under the control of the sensor driver 104, and the photoelectrically converted read signal is amplified to a predetermined level in the amplifier circuit 105.

The amplified reading signal (analog signal) is sent to the next stage A.
/ Supplied to the D conversion circuit 106 and white level setting circuit 1
13 and the black and white reference voltage supplied from the black level setting circuit 114, for example, one pixel has 8 pixels) (256
gradation) is converted into a digital signal representing the multi-value density.

The read data converted into a digital signal is supplied to the frame memory 107 before being subjected to r correction processing, and at the same time it is not written to the memory, a density detection unit 108 is used to detect the average density of the entire card. Also supplied.

A γ correction curve selection unit 109 is connected to the density detection unit 10B, and the γ correction curve selection unit 109 selects a plurality of γ correction curves in the next stage γ correction circuit 110 according to the detection result of the average density in the density detection unit 108. Control signal for selecting the optimal γ correction curve from among. generate a number.

When the reading of the entire card is completed, reading of the data written in the frame memory starts, and the read data is transferred to the γ correction circuit 110 in order to perform optimal γ correction processing
supplied to The data that has been subjected to optimal γ correction processing in the γ correction circuit 110 is subjected to binarization processing using pseudo gradation processing, such as dither processing, error diffusion processing, etc., in the next stage binarization processing section 111. After that, the printing unit 112 prints the image using, for example, a printer using a thermal recording method.
Use as image output for card.

Here, a method of performing optimal gamma correction processing according to the average density of the card, which is a feature of the present invention, will be explained in detail with reference to FIGS. 5 to 7.

FIG. 5 shows the concentration detection section 10B and the γ correction curve selection section 10.
9, the density detection section 10B is composed of a full adder circuit 108m and a latch circuit 108b, and the r correction curve selection section 109 is composed of a decoder circuit 109h.
, OR circuit 109b.

It is composed of an encoder circuit 109c.

The upper 3 bits of the visual reading signal output from the A/D conversion circuit 106 are input to the A terminal of the full adder circuit 108a constituting the concentration detection section 10B, and the upper 3 bits of the visual reading signal output from the A/D conversion circuit 106 are input to the B terminal. The cumulative addition value up to the read signal is fed back. As a result, the cumulative addition value up to the visual reading signal appears at the output of the full adder circuit 108a, and this is input to the next stage latch circuit 108b. The latch circuit 108b receives latch signals corresponding to the reading* and b signals to hold the cumulative addition value from the visual reading to the shi signal, and feeds it back to the B terminal of the full adder circuit 108a. This signal processing is repeated from the start to the end of card reading. That is, the cumulative addition value of the density over the entire reading plane of the card can be determined at the time when the latch signal resulting from the last reading signal of the card is input.

Here, the maximum value of the cumulative addition value to be processed is related to the number of gradations of the read signal to be handled (here, 3 pits = 8 gradations) and the number of sampling pixels in the main scanning and sub-scanning directions. Needless to say.

The r correction curve selection section 109 outputs a control signal for selecting the most suitable gamma correction curve for the card used from the cumulative sum of the entire reading plane of the card detected by the density detection section 108. . Here, in consideration of the scale of the circuit, the binary signal (dat-ds3) of the upper three bits of the cumulative addition value detected by the density detection section 108 is treated as the average density.

The decoder circuit 109a converts the average density of the upper three bits of the cumulative addition value into eight density levels (d1 to da).
), and the next OR circuit 109b divides the 8 density levels into 5 density levels (densities D1 to D5).
5 types of γ correction curves (rx-rs) assigned to the address space of the r correction calculation ROM.
A selection signal (sl~
85) This selection signal is converted into a 3-bit control signal (C1 to as) for controlling the address space of the arithmetic ROM in the encoder circuit 109c at the next stage,
The signal is supplied to the arithmetic ROM of the γ correction circuit 110.

FIG. 6 shows the calculation RO used in the γ correction circuit 110.
FIG. 7 shows the input/output relationship of the data of the γ correction curves (γ1 to γ5) stored in the arithmetic ROM. In the figure, the input of the calculation ROM (A!~As)
is an input terminal for a read signal having a gradation level of 8 bits per pixel from the frame memory, and A! + AIO
+All is a ROM in which the data of the γ correction curve is stored.
It is connected to the r correction curve selection section 109 at an input terminal for a control signal for switching the address space of the . ODo%
ODs is an output terminal for output data subjected to γ correction processing.

γ1 to r5 of the γ correction curve are the average density of commonly used cards, such as a whitish card (density D1), a slightly whitish card (density D2),
When the cards are classified into five levels, such as intermediate cards (density D3), slightly dark cards (density D4), and dark cards (density D5), the settings are made so that the optimum print quality cannot be obtained for each card. There is. These γ correction curves are
The control signal (ct
By switching the address space of the calculation ROM by ~Ca), for example, if the average density of the card is D1 or more, rl, if D1zD2, r2, if D2-D3, r3, if D3-D4, r4, D4. If it is below, γ5 is selected, and the optimum γ correction curve for the read card is automatically selected and γ correction processing is performed.

Note that the number of classifications based on the average density of the cart 9 and the types of γ correction curves corresponding thereto are not limited to the five types listed here.

Consisting of an encoder circuit 109c, the density detection means 10
From the 3-bit binary signal (ds1 to dss) representing the average density of the medium to be read output from
The control signal (el"-e3) was created, but
The above 3-bit binary signal can also be used as a control signal for the arithmetic ROM. In this case, the contents of the arithmetic ROM may be configured to store, for example, eight types of γ correction curve data in each address space, corresponding to the binary numbers O to 7 represented by the three bits. Preferably, the density detection means 108 also functions as the γ correction curve selection section 109 described above.

(Effects of the Invention) As described above in detail, the image reading device according to the present invention can handle a wide variety of design cards, from whitish cards to black cards. By detecting the average density of the card from the set γ correction curve, the γ that matches the card is determined.
Since the optimum γ correction process is performed by selecting the correction curve, there is an advantage that clear image reading can be obtained for all cards. Further, the concentration detection section according to the present invention has a simple structure of cumulative addition means for multivalued digital signals, and has the advantage that the amount of jihad can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an image reading device of the present invention, Fig. 2 is a block diagram of a conventional image reading device, Fig. 3 is a block diagram of an arithmetic ROM in the conventional device, and Fig. 4 is a gamma correction in the conventional device. The curve diagram, FIG.
The figure is a block diagram of the arithmetic ROM in the device of the present invention, and FIG. 7 is a diagram of five types of γ correction curves in the device of the present invention. In the diagram, 100...Cashing card, 101...
Light source, 102... Convergent rod lens array, 103
...-dimensional image sensor, 104... sensor drive unit, 105... amplifier circuit, 106... A/D
Conversion circuit, 107... Frame memory, 108...
Concentration detection unit, 109...γ correction curve selection unit, 110.
...γ correction circuit, 111...binarization processing unit, 112.
...Printing section, 113...White level setting circuit, 114.
...Black level setting circuit. Conformity /) Mll: # “Keru r゛ correction kakuzuen J ROM

Claims (2)

[Claims] (1) A means for photoelectrically converting an optical image of a medium to be read, such as a cash card, and further converting it into a digital signal representing multi-level density; a frame memory for storing the digital signal; and a frame memory for storing the digital signal; , a density detection means for detecting the average density over the entire surface of the medium to be read; a γ correction curve selection means for outputting a control signal for selecting an optimal γ correction curve according to the detected average density; A gamma correction means that holds a plurality of gamma correction curve data corresponding to the average density of the medium and performs correction processing on the digital signal stored in the frame memory using the selected gamma correction curve. image reading device. (2) The image reading device according to claim 1, wherein the density detection means detects the average density of the medium to be read by cumulatively adding the digital signals.