JPS5870379A - Optical picture reading method - Google Patents

Abstract

PURPOSE:To read a picture by a picture quality which resembles an original picture, by detecting the density of a ground of a form before reading the picture image, executing this detection at a position which is as near as possible to said picture image, and reading said picture image by a gradation characteristic being suitable for the detected ground density. CONSTITUTION:A picture to be read (impression shadow) 2 is positioned so that a frame 1a is superposed on a window frame of a positioning frame plate 3, by which density of a ground of a form in positions 7a, 7b which are as near as possible to said picture 2 is detected by a line sensor 6, it is detected as ground density of the form, is A/D-converted, and a digital (gradation) signal showing a density level is transferred to a gradation characteristic correcting memory 11. In said gradation characteristic correcting memory 11, ground density of the form is read as a parameter, and plural gradation informations to the same density level of the picture element are stored. Accordingly, the gradation information corresponding to ground density is outputted in order from said memory 11.

Description

[Detailed description of the invention] The present invention is a seal imprinted on unspecified paper.

The present invention relates to an optical image reading method for reading an image such as a fingerprint and generating gradation information thereof.

Recently, financial institutions such as banks have been required to mechanize seal verification operations, reduce the time and space required to manage seal stamps, and shorten search times. A system is being considered in which the image data of the seal is stored in a customer information file at a center, etc., managed collectively, and is visually output online to a terminal device at each branch as necessary.

The present invention is used in such a system to create image data of customers' seals, and its purpose is to use existing seal stamps with various background colors and stamping positions as they are. The goal is to read the image at a quality that is as close to the original as possible. The feature of the present invention that achieves this object is to align the image to be read, such as a seal imprint, with a reference position, and read a specific area of a paper such as a seal stamp using an optical sensor at a position fed a predetermined distance from this reference position. The output signal of this optical sensor is converted into a digital value, and the average value of the roughness level in the range where the density level above a certain density level is deleted from the specific area is calculated, and this average value is stored as the background density of the paper. , gradation information corresponding to each density is stored in memory in advance according to gradation characteristics with the background density as a parameter, and when reading the image to be read, gradation information corresponding to the background density is stored in advance. Reading the tone characteristics and the image I) The purpose is to read out the corresponding tone information from the memory depending on the acidity.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a perspective view schematically showing the configuration of an embodiment of the present invention, in which a frame 1a for specifying the position where a seal is affixed is printed, and a customer's notification seal is affixed within this frame la. 2, a seal imprint stamped in the frame la; 3, a positioning frame plate for aligning the seal imprint 2 with the reading reference position; 4, a light source that irradiates light to the reading position; 5, a lens; 6
is a line sensor that receives reflected light from the reading position via the lens 5 and converts it into an electrical signal, and is an optical sensor similar to those used in OCR (optical character reader) and facsimiles. .

Figure 2 shows the seal frame of the seal stamp 1 in detail.The vertical and horizontal dimensions of the frame 1a are assumed to be the maximum dimensions of a commonly used seal. Generally, the size is such that it remains in the area. In the figure, 7a and 7b are areas scanned by the line sensor 6 to detect the acidity of the base of the seal stamp 1 when reading the seal impression 2.The reason why these areas 7a and 7b are set at the positions shown in the figure is generally Many of the seals used in banks are round or oval, and even if the seal is stamped on the upper side of the frame la, this area often remains as a blank space, making it difficult to use the base material. This is because it is easy to detect the concentration of

FIG. 3 is a block diagram schematically showing the circuit configuration of an embodiment of the present invention, in which 8 is an amplifier circuit for amplifying the output signal of the density detection at each scanning position by the line sensor 6, and 9 is the output of the amplifier circuit 8. An A-D converter converts the signal into a digital signal; 10 is a transfer control case that switches the destination of the acidity detection digital signal output from the A-D converter 9; 11 is a transfer control case that sets the base density of the paper to 24 lameter; The gradation characteristic correction memory stores gradation information corresponding to each density in advance according to the gradation characteristics to be applied, and is composed of, for example, a ROM (read only memory).

Reference numeral 12 denotes a main control circuit that organically controls the operation of each of the above components and the operation of a feeding device (not shown) and also executes a given calculation, for example, executes a pre-stored program according to a predetermined procedure. It consists of a microcomputer, etc.

Next, the operation of the above configuration will be explained.

First, the seal stamp 1 to be read is positioned so that its seal imprint 20 frame 1a overlaps the window frame of the alignment frame plate 3. Seal stamps 1 of various sizes and materials are currently used, and the position of the frame 1a for stamping a single stamp also varies.

So, move the seal stamp 1 back and forth, left and right, and make the impression 2 like this.
to the reference position. The seal stamp 1 is read directly by a feeding device such as a feeding roller or (5) feeding belt, which will not be shown later.
send it to the department. When the seal stamp 1 advances by a certain distance tl, the base detection area 7a is reached.

7b reaches the reading position by the line sensor 6.

This is detected by the feeding amount by the feeding device or by a separately provided position sensor, and this detection signal s1 is supplied to the main control circuit 12. The main control circuit 12 thereby sends a switching command signal 82 to the transfer control case 10 so that the digital signal of the acidity detected at that time is transferred to the main control circuit 12.

In the background detection at the start of the above reading, the above area 7
Among the densities of each pixel of a and 7b, the density above a certain level is regarded as a stain or dirt and is deleted. Experimentally or empirically, this density level is clearly considered to be too low to be the density of the background, and the main control circuit 12 calculates the average value of the detected density of the deleted remaining pixels based on this threshold value, and calculates the average value of the detected density of the deleted pixels. It is regarded as the density of the base of seal stamp 1 and is stored. The detected density level, that is, the gradation (6
) is set to 32 gradations from O to 3 levels, for example.
A digital signal representing one of the 32 gradations is transferred to the main control circuit 12 in accordance with the magnitude of the detected density analog signal of each pixel. There is no particular restriction on the number of pixels that one-dimensionally constitute the areas 7a and 7b for detecting the background, but if it is too small, the detected background density will be ambiguous, and if it is too large, the density of the detected background will be ambiguous. There is a possibility that the detection rate of pixels other than the above will be high. Area 7
The digital signal representing the gradation of each pixel of a I 7b is temporarily stored in a memory (not shown) of the main control circuit 12 in order to calculate the above-mentioned average value, and is further read out and subjected to the above-mentioned calculation.

When the density level of the background of the seal stamp 1 is detected and stored in this way, the main control circuit 12 completely stops sending out the switching command signal S2, and 9, the digital signal representing the density level is transferred to the gradation characteristic correction memory 11. Do it like this. When the digital signal is applied to the gradation characteristic correction memory 1, it forms part of its read address information. Further, the main control circuit 12 simultaneously transfers address information corresponding to the average value of the density level of the base to the gradation characteristic correction memory 11,
A specific address area of the correction memory 1 to be read out is specified using the address information representing the density.

The gradation characteristic correction memory 11 stores a plurality of gradation information for the same density level of multiple read pixels using the paper background density as a parameter. FIG. 4 shows the relationship between the read density level and the gradation level. Gradation level is from O to 1
It is divided into 16 gradations up to 5, and the paper background detection density is A, B, C.

The gradation characteristics differ depending on the D as shown in the figure.

The gradation characteristic correction memory ll allocates a specific address area for each of these different gradation characteristics, stores the gradation information from 0 to 15 in the address corresponding to each reading accuracy in each address area, and One of the previous address areas is specified based on the base detection tension information from the main control circuit 12, and one address in that specific address area is selected based on the pixel reading sensitivity level information. The gradation information can be read out.

In this way, the preprocessing for reading the seal impression 2 is completed, and the reading of the seal impression 2 is finally started in response to the feeding of the seal stamp l.
The seal impression 2 and each pixel around it are stored in the memory 1 according to the gradation characteristics according to the base density of the seal stamp 1 and its reading density.
The corresponding gradation information is sequentially output from 1.

As explained above with reference to the embodiments, the present invention detects the density of the background of the paper before reading the image to be read, performs this detection at a position as close to the image as possible, and selects a gradation suitable for the detected background density. Since the image is read based on the characteristics, there is an effect that gradation information is generated with an image quality very close to that of the original image even if it is not an image on a specified paper.

It goes without saying that the present invention is applicable not only to reading seal impressions as in the above embodiments, but also to reading fingerprints, signatures, and various other images.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically illustrating the configuration of an embodiment of the present invention, FIG. 2 is a plan view showing a portion of FIG. 1 in detail, and FIG. FIG. 4 is a block diagram showing an outline of the circuit configuration, and is an explanatory diagram of an example of setting gradation characteristics in the present invention. 1... Seal stamp, 2... Seal imprint, 3... Frame board for positioning, 6... Line sensor, 7a, 7b... Area for base detection, 9... A-D converter, 10... Transfer control case 8-h, 11... Gradation characteristic correction memory, 12...
・Main control circuit. (10)

Claims (1)

[Claims] In an optical image reading method that optically reads images such as seal impressions or fingerprints stamped on unspecified paper and generates gradation information, the image is aligned with a reference position and the image is read a predetermined distance from this reference position. A specific area of the paper is read by an optical sensor at the feeding position, the read density output is converted to a digital value, and the average value of the density level in the range where the density level above a certain density level in the specific area is deleted is calculated. At the same time, this average value is stored as the background density of the paper, while gradation information corresponding to each density is stored in advance in a memory according to gradation characteristics with the background density as a parameter, and the gradation information corresponding to each density is stored in advance in the memory. An optical image reading method, characterized in that when reading the image, corresponding gradation information is read from the memory based on gradation characteristics according to the background density and the reading density of the image.