Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
  • B07C3/00—Sorting according to destination
  • B07C3/10—Apparatus characterised by the means used for detection ofthe destination
  • B07C3/14—Apparatus characterised by the means used for detection ofthe destination using light-responsive detecting means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
  • B07C3/00—Sorting according to destination
  • B07C3/20—Arrangements for facilitating the visual reading of addresses, e.g. display arrangements coding stations

Definitions

• Image processing method in particular in a postal sorting installation.
• the present invention relates to an image processing method, in particular in a postal sorting installation.
• the latter case corresponds to equipment of the "SIRCA” type (Integrated Address Recognition and Coding System).
• SIRCA Integrated Address Recognition and Coding System
• the images of the letters are subject to automatic recognition, and in the event of failure, they are presented to an operator on a video console (video coding).
• a modern treatment process includes:
• the image is "dirty", which means that it contains parasitic information, which has nothing to do with the address that one wishes to examine: it can be either spots of origins various, but also of inscriptions, such as postmarks or others, which are outside the address area proper, but which are however reproduced on the video screen. This spurious information is an additional cause of fatigue for the operator and requires an increase in the memory capacity necessary to store the image.
• the object of the present invention is to remedy these drawbacks, that is to say to provide an image processing method which makes it possible to obtain images as "clean" as possible, and in which the prior localization of the information to be examined on the screen is as regular and usable as possible, this process being specially adapted for the treatment of addresses which could not be read by an automatic reading device, for example handwritten addresses.
• the invention provides a method of processing, in particular in a postal sorting installation, of images comprising an address, this method comprising the following steps:
• processing of the image elements stored in memory comprising at least the sending of the image elements to the video screen of a reading station with a view to identifying an address which does not could be read by an automatic reading device.
• the blocks whose dimensions in the y direction, that is to say perpendicular to the direction of the address lines, are clearly less, or clearly greater, are not stored in memory. writing line determined beforehand on the image of the object.
• the signal density of each block is determined, that is to say the proportion of pixels (elementary spaces of the image) having the same binary value corresponding to the presence of a read sign, and the blocks whose density deviates too much from the average density of a block containing writing parts are not stored in memory.
• Elimination based on the density criterion makes it possible to ignore large spots, which lead to blocks of very high density, while elimination of blocks of low density, for example correspond to inscriptions or marks that are oblique to the reading lines. In both cases, it is again a question of eliminating parts of spurious images.
• the pixels (elementary parts) of the binary image are grouped in "rectangular blocks" each containing an equal number of pixels, this number being greater than one but at most equal to that which corresponds to the minimum dimension of the usual handwritten letters, and a first binary value is given to all the pixels of a block of which no pixel has the moaner corresponding to the presence of a read sign, and a second binary moaner opposite to all the pixels of the other adornments, and the blocks are delimited so that they contain all the blocks having this second binary moaner, which are joined to each other, and which may contain parts of address.
• the blocks leaving said second binary value and which are isolated or form an isolated assembly comprising a number of paries less than a fixed groover are left outside the blocks.
• the reconstructed image be subjected to a so-called "compression” treatment before it is stored and / or sent. at the reading station, preferably this compression treatment is done according to the Read method.
• This compression operation which is a conventional operation, is to reduce the amount of information to be stored and transmitted, and therefore to save transmission time, and to reduce the cost price of the installation. .
• Figure 1 is an overall diagram of the process.
• Figure 2 is a view of an envelope bearing a handwritten address.
• Figure 3 is a view of the envelope portion taken into account by the image capture machine.
• Figure 4 is an enlarged view of part of Figure 3, schematically creating a block.
• Figure 5 is a view similar to that of Figure 3, with indication of the blocks
• Figure 6 is a view similar to that of Figure 5, corresponding to the image that finally appears on the operator's screen.
• FIG. 1 is a block diagram showing the entire process of the invention.
• the reference 1 designates an image capture and automatic reading machine
• an interface 2 receives a binary video image from machine 1.
• the reference 3 designates a station for transforming columns into lines. The reason for this transformation is that the machine used in the practical example for capturing images operates in rertical lines, the letters scrolling in front of it horizontally. It is necessary, with this type of material, to transform the image into an image comprising horizontal lines, so as to be able to operate with a material of current type. It is clear that with other image capture equipment, this post 3 would possibly not have its raison d' scope.
• the images are then sent to an image buffer memory 4.
• the reason for this buffer memory is as follows: the image capture machine 1 supplies images of letters at a rate of 15 per second, in the practical example described.
• the input is made on a height of 64 mm on letters from 140 to 220 mm, with a resolution of 8 points to the millimeter in each dimension.
• the binary images provided have 512 x 1,760 dots, or 901,120 dots; the memory necessary to store such an image therefore has a capacity of 112,640 bytes.
• the automatic reading unit processes several images in parallel according to a "pipeline" structure, and can take up to a second to say if it has been able to recognize an address.
• the buffer memory 4 only ensures the storage of the images necessary for image processing as will be seen below. In fact, the memory 4 must only allow the storage of at least two images of 112 kilobytes, one of these images being in the process of acquisition, and the other being processed.
• the images coming from the interface 2 and from the transformer station 3 are sent to a station 5 for searching for information blocks, connected to a microprocessor 6 for image processing. All the operations carried out at stations 5 and 6 will be explained using figures 2 to 6.
• Figure 2 is a complete image of the back of a letter.
• the image capture machine 1 retains on this letter only a strip 64 mm high, which makes it possible to obtain the image of FIG. a circular stamp which constitutes a parasitic image element, and it is also observed that the left ends of the address lines are not aligned vertically.
• Figure 4 corresponds to a partial street, greatly enlarged, of Figure 3.
• a grid materializes the limits of the "trimmed" between which the image is distributed; in practice, the size of a trim is of the order of 1 mm by 4 mm. Hatching has been applied to the trim 22 which contains a part of the reading element, that is to say at least one pixel of which has a binary moan different from that of the background.
• FIG. 5 shows all of the blocks which have been formed on the image represented in FIG. 3. It can be seen that these blocks correspond to all of the address elements, with however two parasitic blocks 30, 31, one corresponding to the circular stamp 20 located at the top left of the image, and the other to a horizontal line located at the bottom of the image, below the address. The microprocessor then eliminates these blocks by a comparison of their dimensions arec the height of the lines as it emerges from the other trimmed,
• Figure 6 shows the reconstructed image after it has undergone an additional cropping operation consisting in moving the blocks with respect to each other, and with respect to the limits of the image, so that the block which contains the code postal 32, that is to say the first from the bottom and from the left, is troure in the location which was recognized the most serious during the preliminary studies, and the other blocks were placed at suitable distances from each other, both vertically and horizontally.
• this last operation of placing the blocks selected according to the ergonomic criteria is done in an image reconstruction unit.
• This unit receives on the one hand, from the image processing microprocessor 6, the coordinates of the blocks which have been retained for the rest of the operations, to the exclusion of the other blocks, and on the other hand, it receives memory buffer 4 the information concerning the content of these blocks. From the information coming from these two sources, and according to the program of the microprocessor 6, the unit 7 for reconstructing the images proceeds to the positioning of blocks according to the criteria defined above.
• the image reconstruction unit 7 also proceeds, on the order of the microprocessor 6, to reduce or dilate the blocks, so that the reconstructed or "cropped" image occupies in a memory space approximately 50,000 bytes, Let us call that the initial image occupies in a memory a space ranging between 71,680 and 112,640 bytes, these numbers corresponding respectfully to letters of 140 mm and 220 mm long.
• the processing operations to be carried out in the image reconstruction unit 7 relate to a number reduced blocks, 10 to 15 blocks in general.
• the use of a fast microprocessor, of the "68000" type from the company THOMSON / EFCIS is possible, it leads to a calculation time which can be estimated at around thirty milliseconds, which is compatible with the rate 15 frames per second.
• the images leaving the image reconstruction unit are sent to a buffer memory 8. From this buffer memory, they are sent to a clear image compression unit.
• This compression unit consists of two integrated circuits of the "AMD 7970" type from the company ADYANCED MICRO DEVICES, operating as a flip-flop. The reason for this arrangement is that the compression time of an AMD 7970 circuit is approximately order of 100 milliseconds, higher than the expected rate of 65 milliseconds per image. The compression ratio provided by this circuit is from 15 to 30. This results in compressed images having a size of the order of 3 kilobytes.
• the memory 8, which powers a compression unit 9 must make it possible to store at least three images of 50 kilobytes: one being received, the other two being processed by each of the two AMD 7979 circuits, the allocation of these memories being made by circular permutation.
• the images leaving the compression circuit are sent to a compressed image buffer 10, which too must allow the storage of three images but of a smaller size: only three kilobytes each, two of these images being loading by the AMD 7970 circuits, and the third being in the process of transfer by the aral.
• the three memories are also assigned by circular permutation.
• the compressed images leaving the buffer memory 10 are sent to the system management computer 11. This computer is connected via a link 12 to twenty reading stations 13, of which only three were represented.
• Each reading station comprises on the one hand a keyboard-screen assembly 14 and a decompression unit 15.
• This unit consists of a circuit of the "AMD 7970" type, already mentioned above; it ensures the decompression of the 3 kilobytes of the compressed image into the 50 kilobytes of the image restored on the screen.
• This restored image indeed includes 400 x 1000 points.
• the link 12 between the management computer and the reading stations is a "ETHERNET" type link.
• the arrangement according to which the images are decompressed at the reading station, and not at the level of the management computer makes it possible to reduce in a very considerable proportion the load of the "ETHERNET" connection system.
• the management computer 11 is also connected on the one hand to a disk memory unit 16, and on the other hand to the "ELIT" machine (Indexing and Sorting Reading Equipment) 17 so as to transmit to it either the routing code which was determined at the reading station for printing on the letter itself or the street delivery code for immediate sorting of the letter.
• ELIT Indexing and Sorting Reading Equipment
• the present invention made for postal sorting is directly adaptable by the skilled person to other cases of applications that may require other ergonomic criteria for the presentation of images. It should also be noted that the inention can be part of an automatic character recognition system, advantageously constituting a preprocessing step of such a system.
• the method according to the invention is implemented by the collaboration of hardware means and software means. If we accept longer operating times, we can envisage a fully software implementation.

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• Sorting Of Articles (AREA)
• Character Discrimination (AREA)
• Character Input (AREA)

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• 1985
  • 1985-10-25 FR FR8515868A patent/FR2589267B1/fr not_active Expired - Lifetime
• 1986
  • 1986-10-24 WO PCT/FR1986/000369 patent/WO1987002602A1/fr not_active Ceased
  • 1986-10-24 EP EP19860906351 patent/EP0245330A1/de not_active Withdrawn

Non-Patent Citations (1)

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