SE449142B - KIT FOR AUTOMATIC RECOGNITION OF MARKINGS ON A MACHINE EXTENDABLE DOCUMENT EQUIPMENT FOR IMPLEMENTATION OF THE KIT - Google Patents

Description

10 15 20 25 30 35 40 449 142 2 . . sorterarel'Then the selection matrix can be in the same document review read together with an OCR (optical recognition) line. The information content of a mark is obtained from the mark the position of the ring within a specified document repression. Therefore must a device for automatic recognition of handwritten markings first carefully determine the pre-printed check box position in relation to its sensing frames. The more accurate one succeeds in achieving this, the less the risk of you coordinate the selection with one or more incorrect ones places ie. check boxes.

For this purpose, press for example from CH-PS 498,451 known marking documents, time marks in a parallel with the bar line arranged with the rows of the selection matrix. These rates: marks are placed flush with a column in the sensing matrix.

Since the selection matrix is usually read in the row direction, the position of the columns in the sensing grid is thus defined.

The line coordination takes place at known marking readers through the mode for the lower edge of the document with a determined raster distance- Difficulties arise in this inflexible coordination when a document to be read, by misaligning the document the transport distance is shifted in height or passed the optical sensor of the device with a certain inclination. But even with the correct transport of the document in height in height to the sensing device, a height shift is obtained. for the selection matrix, for example, when the document is not properly cut. Oblique positions can always occur when the document is at the transport is not exactly aligned at its edges. All these deviations from a standardized position lead despite that of the roof line given the column layout for the selection matrix to be incomplete accuracy, so that markings can, where appropriate, be an incorrect row and column position is arranged.

The object of the invention is therefore to provide one procedure of the kind mentioned in the introduction, which despite a such displacement or such an inclination of the displacement printed selection matrix in relation to the sensing the device's raster provides a high level of recognition security in one or both coordinate directions, whereby it is possible to smooth out the said error positions of the marking matrix in holding to the sensing grid. 10 15 20 25 30 35 40 449 142 3 According to the invention, this task is solved in one way the initially mentioned kind by a procedure according to with the features set out in claim 1. The special the advantage of this solution is that it enables pure electrical tronic correction of the sensing result by means of a before the selection matrix placed so-called code column. This contains in addition to the document type, characteristic code marks two positional marks, the displacement of which in the row direction, expressed in column distance in the sensing grid, is determined and evaluated on such that in the sensing result the positions of the marking the boxes for each column in the selection matrix are corrected.

Advantageous further developments of the principles of the invention thought are set out in claims 2 and 3.

The invention will be described in more detail in the following in connection to the embodiment shown in the accompanying drawing with Figs. 1-3 lead example. _ Fig. 1 shows a block diagram of the principle the construction of a device for the automatic recognition of rings.

Fig. 2 shows a document section of which the structure y of the selection matrix is shown.

Fig. 3 shows a block diagram of a coupling device for image correction skew for image data in each sense column.

Fig. 1 is a block diagram of the basic construction of a device for automatic recognition by hand inscribed markings on a machine-evaluable document ment. The recognition device consists of an optical marking device. sensors and electronic coupling devices for recognition marking. The selection sensor contains a sensor optical optics 10 and an optical transducer 11. It is for example placed in the document input part of a document sorter at a reading station location on the document transport route.

At the position stations, the documents (2) to be sensed are kept - in the chemically indicated way - of a suction drum (not shown) in the direction of the arrow 21.

The design of this document 2 is shown in more detail in Fig. 2. The document contains one of 17 lines Z1 to 217 and an arbitrary number of columns S existing selection matrix. IN the intersection points between rows Zn and columns S are marked 10 15 20 25 30 35 449 142 4 MK squares pre-printed with blind colors, which are to lay fixed the size and position of markings M. Those for printing of the check boxes MK use the blind colors are outside the sensitivity spectrum of the optical-electric sensing unit 10, 11 and therefore does not affect the recognition of the markings. The blind colors are light yellow, amber or red color tones. The MK check boxes are marked by drawing of a horizontal cross "X" with a soft pencil or ballpoint pen with the writing color black or bla. Also other markings M, for example standing cross "+" or vertical resp. diagonal dash can be detected. The marking with horizontal cross offers however, in the present case the greatest recognition security.

Above the selection matrix is a barred TZ with i black printed beat marksTM. The position of the beat marks TM defines the position of the selection matrix columns S. A recognition races only take place when a beat mark TM is found. Basically of this arrangement, the selection matrix can, if desired broken by other information, when the roof line in these places is not contains nàgia tact land TM.

The selection matrix is read in the opposite direction to it indicated by the arrow 21 from the right at left. The first column read is a code column CS.

This contains two first, spanning two rows, in black color printed position marks CM1 in the first two rows Z1, 22 and at the height of the 13th and 14th rows Z13, 214.

As will be seen in more detail below, it will be by means of in these location marks CM1 a possible skewed transport of the document 2 to be detected the code column CS contains several preprints from a combination of and electronically equalized. In addition, for example 3 of 7 elements consisting of code marks CM2, which defines the nature of the selection matrix to be sensed and the nature of the document.

If the selection matrix is printed in blind colors, linearly throughout the matrix continuous dividing lines between columns respectively, rows are divided into fields, and if within each one of the fields shall be applied one dependent on the lighting, equal number of markings, so you can for all fields carry out a probability test of a certain number of rings. 10 15 20 25 30 35 40 449 142 5 Turning now to Fig. 1, such a document is depicted. 2 during the passage past the mark reading station over the sensing the optics 10 on an auto scan line, i.e. a row of 128 photodiodes in the optoelectric converter 11. Photodiodes extends in the direction S of the matrix columns. Through a sensing connection in the converter 11, the information is converted from the photodiodes of a series analog video signal VS.

To achieve safe sensing of well-drawn well-designed markings such as markings on dirty documents are taken into account to the brightness of the character background, i.e. the current maxi- grind the white value in the row of the pixel to be sensed, and this takes place in a signal conversion unit 3 at quantize1_ the video signal VS to one of the black-and-white values standing image pattern. From the specific brightness of the character the basis derives three vertically scattered black-threshold values, by means of which three different image patterns are generated from the original video signal VS. A fourth special threshold used for evaluation of the high-contrast pre-printed rates the TM marks on the roof line TZ as well as the position marks CM1 and the code marks CM2 in the code column CS. This derivation of threshold values from the established basic light values mean in the first hand taking into account the existing contrast between characters and background and at the same time compensate for any sensitivity to the various photodiodes in the optoelectric the transducer 11.

In the following steps, first process it further with the different threshold values quantified the image pattern. In doing so, kept out of position of the beat marks TM in a preprocessor 41 information regarding the position of the selection matrix rows Zn and columns S. In addition, an event is detected and smoothed. any existing skewed displacement of the document 2 by means of a in the following more detailed description of the coupling device for inclined position correction. Since the position of rows Z1 to Z17 there- after is carefully determined, the sensing information can without appreciable deterioration of the recognition security is reduced by factor 1: 2, i.e. to 64 image lines. Those for this information data required data is obtained from a such parameter memory 42 denoted constant value memory.

In a recognition unit 5, three now run through different evaluations. image patterns and the information 'concerning 10 15 20 35 40 6 449 142 the position of the image pattern in relation to the sensing matrix. May safe determination of whether in a certain position a marking present or not, all pixels are correlated depending in their locations with selected pixels in their environment. Here ~ for required control data is in parameter memory 42. Thus the arrangement of the markings for all image patterns is given.

In a subsequent evaluation unit 61, one is performed probability test for each field in the selection matrix. For For this purpose, pre-known information is used. appropriate marking fields as a criterion. This information is the known size of the selection fields and the number allowed markings M in the marking field. This criterion_is in the form of test programs for different types of documents stored in one additional constant value memory, the probability memory 62. Information the information in the code marks CM2 in the code column CS determines which test program to be used. The probability test now provides as a result, which of those with the three different thresholds certain marking devices that meet the probability criteria and to be used as an approved result. If no probability test can be performed, as none for this required criteria can be used, so it comes with the middle threshold digitized the image pattern to evaluated and given as selection results.

Via a fitting unit 7 the found markings are output as a binary bit pattern in a series of three 6-bit concerns for each column S, and thereby is a bit-place in the last word redundant, so that each row corresponds to a bit location. Interpreter- the output of the output selection information then takes place in the connected data processing facility_ Functional safety devices for this device are tested by means of internal control devices. After each connection of documents with the device for automatic recognition of handwritten markings and after error standardization are performed in it described recognition device recognition of a simulated document with filled selection matrix. All for this one simulation required data is obtained from an additional constant value memory, the simulation memory 8. Even during processing the simulation data are reviewed all described course. The obtained marking results are compared with i the simulation memory B stored setpoints. In the event of non-compliance 10 15 20 25 30 35 40 449 142 7 a fault signal is emitted.

In connection with the 1 fig. 3, the image should now be skewed for image data in each column is described. For this purpose, reference is again made in to the description given in connection with Fig. 2.

As mentioned, by means of the position marks CM1, any position of the document is determined to those in the sense grid the present sensing data must be correlated correctly with the selection matrix.

For this purpose, the coupling shown in Fig. 3 is used. the device. Also for this purpose, the starting points are data obtained from the signal conversion unit 3. Here, however already the number of sensing lines reduced in the ratio 2: 1.

Thus, only 64 image lines are used as a basis the further processing. The coupling device therefore has a row counter 401, which in an evaluation cycle with a 6-bit positions involving binary numbers address one of 64 lines. The output of this row counter 401 is connected to a encoder 402, a programmable cash value memory, which depends on end of the count of the row counter 401 at its outputs 403 to 408 emits line-dependent control signals. Control signal output 403 shall have a control signal Z9 / 245 as soon as the row counter 401 emits an area from the 9th to the 20th resp. from the den 45th to the 56th row. The control signal output 404 emits one positive control signal Z32 when the row counter 401 to the encoder 402 indicates the 32nd row of an evaluation cycle. Analogous applies for the additional control signal outputs 405, 406 and 407, which then have positive control signals, when the lines 64, 2 resp. 3 is indicated by the row counter 401 in the evaluation cycle. The the last control signal output 408 comprises five signal lines for skew correction, the significance of which will be apparent from the following. With this control signal from the encoder 402 synchronized the oblique correction for the image data in each individual case.

To determine the black center of gravity of the position marks CM1, one is used for the signal converter unit 3 connected shift register 409, which occupies image data that is quantized with the to the pre-printed rate resp. code marks W hearing threshold. In this shift register 409, continuous image data from vertically contiguous image 10 15 20 » 'l 30 35 40 449 142 8 element. These are evaluated in an accommodation designed as an AND gate. element 410 as soon as the control signal Z9 / Z45 via the signal control signal the output 403 is output from the encoder 402. This control signal is in this case restricts the triggering of the logic unit 410 to the both areas for sensing lines 9 to 20 and 45 to 56, in which the CM1 position marks are expected to appear.

If four vertically adjacent pixels are black, 1-set a first flip-flop 411. This flip-flop 411 is reset via an OR gate 412 by the control signals Z32 to Z64. The output of this first flip-flop 411 is connected in parallel with the input of two four-digit shift register 413 resp. 414, which for the data transfer from the flip-flop 411 is activated with the control signals Z32 resp. 264.

According to the shift registers 413 resp. 414 is an AND gate 415 resp. 416 connected. These gates are prepared by the control signal Z2 and evaluates the contents of the associated shift register 413 resp. 414. One to the output of these AND gates 415 and 416 connected additional marker switch 417 resp. 418 1-stands therefore as soon as a field of 4 x 4 pixels in one of the sensing lines 9 to 20 resp. 45 to S6 have been evaluated as black. The output signal from the second flip-flop 417 indicates thus whether the upper of the position marks CM1 is determined.

The same applies to the output signal from the third flip-flop 418 regarding the lower of the position marks CMI. Éill de bada with 1 ~ scaffolding entrances coordinated the outputs of the second and third markers 417, 418 are an EXELLER gate 419 connected. This thus reacts as soon as only one of the two connected outputs of the flip-flops 417, 418 have a signal, i.e. that one of the two the position marks CM1 have been determined before the second; The output of this gate 419 is connected to a first binary counter 420 which during the duration of the output signals from the gate in question by means of a control signal Z3 is enumerated. Functionally, this means the following.

The binary counter 420, which includes 3 bit positions, is enumerated to a calculation that corresponds to the column offset for the two position marks CM1. As soon as both position marks have been set, the EXELLER gate 419 locks the binary counter 420. It achieved the counting position of the first binary counter 420 remains unchanged during the document review and is restored 10 15 20 25 30 35 40 449 142 9 at the beginning of the next document through a standardization signal 429.t There is also one for the two markers 417 and 418 additional AND gate 421 connected in such a way that it to a fourth marker flip-flop 422 1-position input emits a 1-position signal as soon as the upper of the two position marks CMI is what has first been established. Also this branded rocker 422 1-position by means of the standardization signal 429. Its to 1-position the output hearing output thus shows a positive signal when the upper of the position marks CM1 has first been determined, i.e. when the detected document is tilted to the right, while it the opposite applies to the output assigned to the reset.

Thus, of the condition of the fourth flip-flop 422, the direction of the document served is derived, under that the arithmetic of the first binary counter 420 defines the column shift of the position marks CM1.

The coupling device shown in Fig. 3 also has for the sole purpose of reading out those stored in an image memory 425 image data in column sections that are offset taking into account to the established inclination, ie. stepped. For this purpose, primarily a first multiplexer 423 is provided.

The current content of the first binary counter 420. Accordingly, the multi- plexer through one of six data inputs to its output. Five of these inputs are connected to the control signal outputs 408 for the encoder 402 oblique correction ring and the sixth input is connected to zero level. The first multiplexer 423 connects thereby depending on the calculation of the first binary counter 420 position through one of the five emitted from the encoder 402, by row counter depending on the instructions such as counting pulse for it the second binary counter 424. The ascent of the second binary the counter 424 is repeated in each row count cycle. From the binary counter 425 counting position shows which column in the image memory is shall be output.

This image memory 425 consists of 20 series-connected shifts. rsgister with 64 elements each. It can thus store inside ~ held in 20 scan columns. When the ideal case at one scanned document there is no skewed deviation, read out : from this image memory in a row cycle the 64 begging data for the same memory column, i.e. the contents of a shift register. According with an established inclination to the left or to the right must 10 15 20 25 30 35 10 449 142 however, the cached image data after a certain number of erasure the displacement of a column is read. Two are used for this purpose additional multiplexers 426 resp. 427, which are connected to part of the image memory's 425 outputs. These bathe further multiplexers 426 resp. 427 is activated selectively by the fourth switch 422. Which of the connected outputs from the image the memory 425 in the respective multiplexer selected is determined by the arithmetic of the second binary counter 424, the 3 positions of which extensive output is connected to the multiplexers 426 resp. 427 elections. The two outputs from the multiplexers 426 resp. 427 is then subjected to logical operation in an OR gate 428, the output of which is connected to the recognition unit 5 and via which the obliquely corrected images are data is forwarded.

In summary, the described coupling the device first the appearance of the two position marks CM1 and then determines how many sensing columns these possibly have are offset from each other. Depending on the size the play of such a column displacement, which size determines the count for the first binary counter, is increased via the encoder 402 and the multiplexer 423 the count for it the second binary counter 424 in each row cycle with one step when after a certain number of rows, depending on the column offset the subsequent pixels from the image memory 425 shall be read a sensing column on the left resp. to the right, which is determined by the line-dependent control signals for diagonal correction of the encoder 402.

In Fig. 3 it is further indicated that the signal converter unit 3 has two outputs for evaluated after different thresholds and each pixel encoded representing image data. According herewith are dotted lines next to what is shown image memory 425 an additional such image memory with corresponding output connections indicated. As previously described, written, this is necessary because image data is quantized with a plurality of thresholds to enable off markings with different contrasts obtain an optimal nings data pattern.

Claims (3)

11 449 142 Patent claims Method for automatically recognizing marks on a machine-evaluable document (2) using an optical sensing device (10, 11) and a coupling device for determining the vertical and horizontal positions for in the form of a matrix printed on the document (2) marking squares in relation to the sensing gratings of the sensing devices, the position determination of the columns (S) of the marking matrix (Zn, S) deriving from the position of clock marks (TM) preprinted in the row in such a way that for each marking column a radial assignment of a memory (425) is performed quantized image data to the lines of the marking matrix, characterized in that in order to smooth the inclination of a document (2) against the sensing gratings of the sensing device (10, 11), the position of position markers (CM1), which are pre-printed on the document (2) in the direction of the column (S) of the selection matrix (Zn, S); that the occurring column displacement between the position marks direction, and that in the image memory (425) stored image data is directed to smooth the oblique position depending on said binary number value in the image memory storage locations corresponding to the rows (Zn) and the columns (S) of the marking matrix. Method according to claim 1, characterized in that for determining the position markings (CM1) mainly in prescribed sensing areas in which a position marking (CM1) must lie, several adjacent sensing columns of the sensing grid are sensed one after the other, within the prescribed sensing area. each sensing column has several adjacent black sensing elements for at least one position marker (CM1), it is determined that when a position marker (CM1) determined in one of the two sensing areas appears, a marker switch (417) assigned to a position marker (CM1) is placed. 418), whose positive output signal characterizes the behavior of 449 142 a position mark (CM1) in the upper and lower sensing areas, respectively, that the direction of inclination of the marking matrix (Zn, S) of the document (2) is derived from that of the position marks (CM1) first appears in this column-wise raster sensing, that when evaluating an additional sensing column, a binary counter '(420) is counted with one in its counter state as long as only one of the two position marks can be determined, and that the counter condition for the entire scanning of the document is maintained as long as both position marks (CM1) are determined. Device for carrying out the method according to claim 1 or 2, characterized in that a multi-digit shift register (409), to which sensing data is supplied in series, is connected with its outputs to a subjunctive logic gate activated during the passage of sensing data from predetermined sensing ranges ( 410), that a first control flip-flop (411), which is arranged to be restored after passing through one of the predetermined sensing areas, is arranged between the subjunctive logic gate and two shift registers (413, 414), the inputs of which are arranged to be activated alternately immediately before the reset of the control flip-flop, that the outputs from these shift registers are connected in parallel to their respective additional subjunctive logic gates (415 and 456, respectively) and their outputs are connected to a second resp. a third control switch (417 and 418, respectively), the positive output signals of which characterize the appearance of a code mark in one of the two predetermined sensing areas, that the 1-position input (J) assigned the outputs of the second and the third control switch ( 417 and 418, respectively) via an EXELLER logic gate (419) are arranged to be connected to an input of a binary counter (420) at the beginning of a column cycle, the parallel outputs of the binary counter being connected to the selection input of a first multiplexer (423), in which, depending on the signal combination thus supplied, one of the data inputs is selected and switched to a connected additional binary counter (424), that the data inputs of the first multiplexer (423) are connected to a line-dependent control signal output control signal output (408) for oblique correction ), and that an image data memory 449 142 I3 (425) is provided, which stores image data for a plurality of sensing columns and has a sense echo lumn coordinated outputs are connected to the data inputs of two additional multiplexers (426 resp. 427), the selection inputs for selecting one of the column outputs of the image data memory are connected to the additional binary counter (424) and also to one of the two outputs of an additional atyr flip-flop (422), which in turn is thus connected to on the appearance of a code mark (CM1) 1-set etyr flip-flops (417 and 416, respectively), that its two coupling teeth indicate the inclination direction of the single position of the document (2).