GB2413422A - System for detecting coding marks on an item of mail - Google Patents

Abstract

A system for use in the detection of coding marks 103, 115 provided on the face of a mail piece 95, 107, the system comprising: at least two modules 87, 91 that are each operable to illuminate the face of a mailpiece, and to capture an image of the face of the mailpiece and any coding mark printed thereon, said two or more modules being configured to illuminate the mailpiece with different wavelengths, or ranges of wavelengths, of light.

Description

Improvements Relating to Postal Systems

Field of the Invention

This invention relates, in general terms, to improvements in postal systems, and in particular to improvements to optical detection systems employed in such systems for reading codes applied to postal items.

Background to the Invention

Aspects of the invention will now be described with particular reference, for illustration only, to the postal system operated by the Royal Mail on behalf of the United Kingdom postal authorities, to the role of integrated mail processing machines (known as IMPs) in that system, and to the coding marks applied to mailpieces by those IMPs to facilitate the automated sorting of mail.

It will be appreciated and should be noted that the teachings of the present invention are not limited to the particular postal system described, nor are they limited to the particular coding marks described herein, or indeed to the application of coding marks by IMPs (alternative coding marks, and coding machines being known in the art).

Figure 1 is a schematic illustration of the various components of a known postal system, such as that which has been operated successfully for many years by the Royal Mail on behalf of the United Kingdom postal authorities.

As shown in Figure 1, collection and delivery of postal items (such as letters, postcards, parcels etc.) in the postal system 1 is split into three general stages, a collection stage 3, a sorting stage 5, and a delivery stage 7.

At the collection stage 3 postal items are collected from a variety of different sources, such as from post boxes 9 dotted around the country, from post offices 11 where the postal items have been handed by the public to the postal authorities, and direct from businesses 13.

The collected postal items are gathered together at local nodes of the postal system and are then sent to one or more district collection hubs 15 where postal items from a number of local nodes are gathered together.

In the second stage 5 of the postal system, all the items sent to the district collection hubs 15 are sent to a so-called "outward" mail centre 17 for sorting. The outward mail centre 17 is so named because it deals with postal items that are, at least potentially, on their way out of the postal system to the addressee of the item.

At the outward mail centre 17, incoming postal items from the collection hubs are sorted into those items which are destined for delivery in designated districts surrounding the outward mail centre (local items), and those which are destined for delivery to other districts which are further afield (remote items).

Local items are finely sorted (for example into items for particular towns and/or streets) and are then sent on from the outward mail centre to appropriate local delivery offices 19 for delivery to the postal item addressees in the third stage 7 of the postal system 1.

Remote items are roughly sorted (for example into items for particular regions of the country) and are sent onto the appropriate inward mail centre 21 for each region of the country. At the inward mail centre (so named because it deals with postal items that are coming into the postal system prior to delivery) the items received from the outward mail centre 17, and from elsewhere, are finely sorted into, for example, items for particular towns and/or streets.

The third and final stage of the postal system 1 is the delivery stage 7 where postal items sorted by the inward mail centre 21 are transferred to local delivery offices 23 for delivery to the postal item addressees. At this stage of the process the local items sorted by the outward mail centre 17 are also delivered by the local delivery offices to the item addressees.

Figure 2 is a schematic illustration of the various processes which occur when postal items are sorted at one of the aforementioned mail centres for example the outward mail centre 17.

As shown in Figure 2, postal items of a variety of different types arrive at the mail centre from the collection hub 15. The arriving postal items 25 can be roughly split into those items 27 (meter pouches) which have been pre sorted into class pouches (red pouches for first class mail, green pouches for second class mail) by customers, those items 29 which have been collected from post boxes 9 and post offices 11, those items 31 which have been received from customers with Royal Mail accounts, and those priority service items 33 which have an additional payment for one of the many different types of priority service.

Typically, pre-sorted items in meter pouches 27 are those which have been collected from businesses in the collection stage 3 of the postal system shown in Figure 1. Account items are typically from businesses which send out a large amount of correspondence, for example direct mailing companies.

Account items are often known as PPI mail (or Printed Postage Impression mail) due to the fact that the envelopes used are usually pre-printed with the appropriate postage. Collection items 29 will typically not have been sorted for class of service (e.g. I st class or 2n class), or for size of mail.

In the next stage of the sorting process, postal items in meter pouches 27 are transferred to a meter table 35 where the postal items are manually removed from the pouches and either transferred to an IMP 37 or direct to a primary sortation facility 39 for further processing.

Collection postal items 29 once received by the mail centre 17 are transferred to the IMP 37 for further processing. Account postal items 31 are passed first to a revenue protection facility 41 before also being passed to the IMP 37.

As mentioned above, all of the collection items 29, some or all of the meter pouch items 29, and the account items 31 are passed to the IMP 37 for sorting. Any mail unsuitable for sorting via the IMP 37 is rejected and sent to the primary sortation facility 39.

The operation of the IMP will later be described, but at this juncture it suffices to mention that the IMP operates (for those items which can be automatically sorted): (i) to detect the class of the postal items (i.e. whether first or second class); (ii) to cancel postage applied to the postal items; (iii) to apply at least one machine readable code (which identifies both the class and the destination) to the postal items, and (iv) to sort the postal items by destination, for example by means of the aforementioned machine readable code.

Any items which cannot be processed by the IMP 37 (or meter pouch items 27 not routed via the IMP), for example because they have an unusual shape or because the address cannot be read, are passed to the primary sortation facility 39 where they are fine sorted by hand into mail for local regions and rough sorted into mail for remote regions. The items for the remote regions are then passed to a secondary sortation facility 47 where they are more finely sorted. Either or both of these sortation facilities can employ machinery, such as coding machinery, to facilitate the sorting process.

Once the postal items have been sorted; either by the IMP 37 or by the primary and secondary sortation facilities 39, 47; they are passed to a despatch facility 49 where they are despatched to local delivery facilities or to an inward mail centre 21 such as that described above with reference to Figure 1.

Figure 3 provides an illustrative schematic view of the various components and manner of operation of the IMP 37.

In a first step S1, the IMP 37 is manually loaded with postal items with obviously outsize (or otherwise objectionable) postal items being rejected by the individuals loading the machine.

The postal items entering the IMP pass up a conveyor belt to a curler 53 where the postal items are spun in a rotating drum. The sides of the drum are slotted so that postal items which are suitable for automatic processing fall through the slots. Postal items which are too large for automatic processing are rejected (in step 57), and move through the drum and fall out the end.

These outsize, or otherwise unsuitable, items are collected and taken to the primary sortation facility 39 for hand sorting. Typically, the IMP will reject any postal items which have a thickness that is greater than 6mm or so.

Postal items falling through the slots in the drum in the curler 53 are passed to a facing and classing unit 55 where the items are appropriately orientated, and the postal class of the items is determined. Again, any items which cannot be classed, or which cannot be faced are rejected (in step 57) and passed to the primary sortation facility 39 for hand sorting.

Correctly faced and classed postal items are then passed to a cancelling unit 59 which cancels postage applied to the items by overprinting the postage with a post mark, for those items with postage that has not already been cancelled.

Once the postage has been cancelled the items are passed to a optical code reader 61 which is configured to read coding marks (as will subsequently be described) applied to postal items which have already been rough sorted into regions by IMPs or other automated sorting machines at other locations in the postal network, or indeed which have already been passed through some other kind of coding machine. If a coding mark is detected and successfully read, the postal item in question is sorted in accordance with that code in step 69. If a code is detected, but cannot be read (for reasons to be described below), the postal item is rejected in step 57 and passed for primary sortation in step 39.

In one such previously proposed coding device used in particular by the UK postal authorities, the coding mark is printed onto the front of the postal item in substantially the same location with an ink which, on illumination with appropriate radiation, is capable of both fluorescing and phosphorescing. As is no doubt well known by those persons skilled in the art, fluorescent materials only fluoresce whilst being illuminated by a light source. Phosphorescent materials, on the other hand, will continue to phosphoresce for a short while after illumination has ceased.

If no coding mark is detected on the postal item, the postal item passes to an OCR device 63 where an image is taken of the address block on the item and an optical character recognition process is employed to attempt to determine the postal code of the address block.

If the postal code can be determined by the OCR device 63, then a coding mark is applied to the front of the postal item by a coding device in step 65 and the associated item is sorted in step 69.

If the postal code cannot be read for any of these items, the image of the address block is sent to a remote post code determining suite and the items in question are passed to a delay line 67 which sidelines the postal item in question for a predetermined period of time. Whilst a given item is in the delay line, an operator in the postcode determining suite is presented with the image of the address block and that operator is provided with a short period of time to determine and input the correct postcode from the image presented.

The correct inputted postcode, once inputted, is assigned to the associated postal item, and an appropriate coding mark is applied to the item (in step 65) and the item is sorted (in step 69).

If the operator cannot identify the correct postcode from the image presented, then the item concerned is rejected (in step 57) and passed to the primary sortation facility 39 for hand sorting.

As shown in Figure 2, items which have been correctly coded and sorted by the IMP 37 are passed directly to the despatch facility 49 where they are despatched to local delivery facilities or to an inward mail centre 21 such as that described above with reference to Figure 1.

Figure 4a is a schematic illustration of a coding mark 68 of the type typically applied by the coding unit 65, and read by the code reader 61 of the IMP 37 shown in Figure 3.

The coding mark shown in Figure 4a is a so-called "four state bar code" or "four state tag code", and is sometimes referred to as the Royal Mail 4-State Customer Code (RM4SCC). The RM4SCC was specially developed by the Royal Mail for automated mail sortation processes, and is used to print for example - the postcode and delivery point suffix (DPS) which identifies both the destination point of the postal item and the identity of the post office from which delivery of the item will be made. Four State Barcodes are also used, amongst others, by the Dutch and Canadian postal authorities.

The RM4SCC is based on 36 barcodes which are capable of representing alphanumeric characters O to 9 and A to Z. and start and stop characters "(" and ")" respectively. As shown in Figure 4a, in the barcode a small black bar extends upwards, downwards or in both directions, and any one alphanumeric symbol is encoded by four bars - two of which have an upward extension and two of which have a downward extension.

Figure 4b illustrates in graphical form the bar combinations and corresponding alphanumeric symbols. In Figure 4b, the symbols to the left of the slash represent upward bar extensions and the symbols to the right of the slash represent downward bar extensions. In each case, a plus symbol means that the bar is extended and a minus symbol means that the bar is not extended.

A particular feature of the four state bar code is that it includes error detection elements which allow a determination to be made not only as to whether a given read code has been read correctly, but also the extent to which a given code has or has not been read correctly.

These elements are read by the aforementioned code reader 61 and used by the IMP 37 to provide an automated determination of whether a given code has been read successfully.

Fig. 5is a schematic illustration of a typical previously proposed code reader 71 which is configured to illuminate and detect codes printed on postal items, as those postal items are passed through the reader 71 by a system of motorised belts (illustrated schematically at 73).

The code reader 71 comprises a first optical illumination and detection system that comprises an ultraviolet light source 75, and a means 77 (such as a video camera) for capturing an image of the mail piece, or at least the part of the mail piece where the coding mark should be, as it is illuminated by the light source and hence as the coding mark, if present, is fluorescing. The code reader 71 further includes a second illumination source 79 (also an ultraviolet light source) that is configured to illuminate passing postal items to cause any coding marks printed on the postal item to phosphoresce, and immediately thereafter in the direction of travel along the belts 73 a means 81 (again such as a video camera) for capturing an image of the postal item, or at least the part of the postal item where the coding mark should be, whilst any coding marks applied thereto are still phosphorescing.

The images of a given postal item or part of a given postal item captured by the first and second image capture means (77, 81) are passed to a computing system 83 which invokes an algorithm that automatically decodes for each image - any coding mark applied to the postal item. Using the inbuilt error detection facility of the four state code, the algorithm then determines for each decoded coding mark (if any) the degree of accuracy of the image obtained and hence the mark decoded, and selects - for further processing (such as sorting in step 59) - whichever of the two decoded marks is determined to be the most accurate.

In the event that the marks derived from, and decoded for both images are determined to be insufficiently accurate for further processing, the postal item in question is rejected in step 57 and passed to the primary sortation facility 39 for manual sorting.

Clearly, the efficiency with which a given IMP, or other automated mail processing machine, can operate (and by inference the efficiency of the entire mail sorting process) is dependent to a large extent on the machines being able to accurately read, and hence decode, the aforementioned four state bar code or similar coding marks.

In the case of a postal item where the coding mark is printed on a part of a white envelope that is devoid (or substantially devoid) of any coloured material (such as advertising or promotional material for example), the machines of the type aforementioned are typically able to obtain reasonably accurate images and hence accurate decoded codes for the postal item as it passes through the code reader 61.

However, as one moves away from this ideal situation, so the accuracy of the images acquired, and hence decoded codes, reduces relatively rapidly to a point where it is not possible to obtain an accurate code and hence is not possible to automatically sort the postal item for delivery.

With the recent predilection, particularly on the part of corporate bulk mail customers, for the use of coloured envelopes or indeed white envelopes with coloured elements (such as advertising material) located where one would normally print a coding mark, the proportion of postal items where the coding marks cannot effectively be decoded, and hence which cannot readily be sorted automatically has been found to be increasing steadily to the detriment of the efficiency of the overall sorting process.

In the light of the above, it would be advantageous if one could devise a more robust code reader that enabled a greater proportion of coding marks to be accurately read, and thereby helped to reduce the detrimental effect of inaccurate code reading on the efficiency of the sorting process.

Object & Statement of Invention

It is an object of the present invention to avoid, or at least alleviate, the problems outlined above, and in particular to provide a more robust code reader. In pursuance of this object, various aspects of the present invention are defined in the accompanying claims. Particular embodiments of those aspects, which are currently preferred, are set out in the accompanying dependent claims.

It should also be noted that whilst particular features have been selected as being of interest, the invention is not so limited and can comprise any combination or permutation of features set out herein whether or not that combination or permutation has been explicitly enumerated in the accompanying claims.

Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of the various components of a known postal system; Figure 2 is a schematic illustration of the various processes which occur when postal items are sorted at one of the outward mail centres shown in Figure 1; Figure 3 is a schematic illustration of the various components of an IMP such as that shown in Figure 2.

Figure 4a is a schematic illustration of a coded indicia of the type typically applied by the IMP shown in Figure 3; Figure 4b illustrates, in graphical form, the bar combinations and corresponding alphanumeric symbols of the coded indicia shown in Figure 4; Fig. 5 is a schematic illustration of a typical previously proposed code reader; Fig. 6 is a schematic illustration of a code reader in accordance with a preferred embodiment of the invention; Figs. 7a to 7d are schematic illustrations of a test postal item and the images resulting from each part of the code reader illustrated in Fig. 6; and Figs. 8a to 8d arc schematic illustrations of a second test postal item and the images resulting from each part of the code reader illustrated in Fig. 6.

Detailed Description of the Preferred Embodiment

As mentioned above, Fig. 6 is a schematic illustration of a code reader in accordance with a preferred embodiment of the invention.

The code reader 85 of this embodiment comprises a first illumination and image capture module 87, followed in the direction of motion of a postal item transport belt 89 by a second illumination and image capture module 91.

The modules 87, 91 are coupled to a computer system 93 of the type mentioned above which is operable to invoke a least errors algorithm to arbitrate between the two images and decode the coding mark, if the coding mark can indeed be determined from the images captured.

The first illumination and image capture module comprises, in this embodiment, a conventional ultraviolet light source and an image capture device such as a video camera. In use, the light source is arranged to illuminate a passing postal item (or at least a part of the postal item on which one might expect to find a coding mark) and the video camera is arranged to capture an image of the illuminated postal item as it passes the module. The first ultraviolet light source is configured to emit light of a wavelength that is suitable for illuminating coding marks printed on a mail piece - generally in the order of 400 to 500 nm, more preferably 400 to 450 nm.

The second illumination and image capture module comprises a series of light emitting diodes, in the preferred arrangement blue light emitting diodes and a second image capture device such as a video camera, preferably an autogain CCD camera. In the preferred arrangement the LED light source is configured to emit light of a wavelength selected from the region of 350 to 380 nm, preferably 365 nm.

In use, the light sources are arranged to illuminate a passing postal item (or at least a part of the postal item on which one might expect to find a coding mark) and the video cameras are each arranged to capture an image of the illuminated postal item as it passes their module. The two captured images, in a similar manner to that mentioned above, are then compared by a computing system which invokes a least errors algorithm to arbitrate between the two images and attempt to decode the coding mark.

The system of the present invention offers advantages over the system previously proposed by increasing the likelihood of a given coding mark being accurately imaged, and subsequently decoded. By increasing the proportion of mail that can be automatically decoded, so the proportion of mail that can be automatically sorted can be correspondingly increased to thereby improve the efficiency of the overall sorting process.

In general terms, the conventional ultraviolet illumination module is provided for illuminating the face of those mailpieces which are whiter in colour, and which have faces that are relatively unobstructed by printed material such as advertising material, or company logos. These mailpieces are generally relatively highly reflective, and as a consequence the intensity of light generated by the LED light source and reflected off the face of the mailpiece for capture by the CCD camera is generally of such a magnitude that the image captured by the aforementioned second image capture module is adversely affected by bloom. In most cases the extent of that bloom is such that any coding marks applied to the face of the mailpiece cannot be deciphered.

In contrast, for those mailpieces of which the relevant face is relatively darkly coloured or which have logos (or other material) in the region where the aforementioned coding marks would normally be printed (i. e. those mailpieces which are generally of relatively poor reflectivity - at least in the region of the mailpiece where any coding marks might be applied), the intensity of light generated by the ultraviolet light source and reflected off the face of the mailpiece for capture by the video camera is typically of an insufficient magnitude to permit a good discrimination of any coding marks applied to the mailpiece, and hence a reliable decoding of the mark. IN such circumstances, however, the intensity of light emitted by the second LED image capture module is often sufficiently high to enable enough light to be captured by the associated camera for a good discrimination, and hence reliable decoding, of any coding mark applied to the mailpiece.

Of course, there will doubtless be circumstances where the face of the mailpiece is so poorly reflective or is so encumbered with advertising or other material that each of the aforementioned modules are unable to provide an image of any coding mark which can reliably be decoded. However, in the majority of cases at least one of the two modules will be able to provide an image of sufficient quality, or both modules will be able to provide an image which whilst not being of the highest quality when viewed in isolation nevertheless enables the coding mark to be determined and deciphered by comparison as between one image and the other.

By way of illustration as to the types of problems experienced, and the advantages provided by the system of the preferred embodiment, reference will now be made to two illustrative mailpieces, and coding mark images obtained from those mailpieces by a system as described herein.

Fig. 7a is a schematic representation of the face of a mailpiece 95 of the type which might be used by a corporate customer. As shown, the majority 97 of the mailpiece is generally white, unobstructed by coloured material, and hence relatively highly reflective.

The face of the mailpiece does, however, include several coloured markings 99, and as chance would have it some of those markings lie in a significant part of a region 101 of the mailpiece in which a coding mark 103 has been applied. Fig. 7b is an enlarged view of this region 101 of the mailpiece 95, and the coding mark 103 applied is clearly visible outside of the coloured markings, and in some of the uncoloured lettering.

Fig. 7c is an enlarged segment of an image of the face of the mailpiece captured using the aforementioned first image capture module (the ultraviolet module) of the system as disclosed herein. As is clearly visible in Fig. 7c, significant proportions 105 of the coding mark 103 are of relatively poor brightness and/or contrast, and as a result, the mark would probably not be decipherable by the aforementioned computer system.

Fig. 7d is an enlarged segment of an image of the same mailpiece 95 captured using the aforementioned second image capture module (the LED module) of the system as disclosed herein. As is immediately apparent from Fig. 7d, the coding mark is much more readily distinguishable as compared to the image depicted in Fig. 7c. Of particular note is that those aforementioned significant proportions 105 of the coding mark depicted in Fig. 7c are now of a sufficient brightness and contrast to enable the mark to be decoded by the aforementioned computer system. That decoding could, in principle and depending on the particular algorithm employed, be accomplished solely on the basis of the image shown in Fig. 7d. However, for better accuracy it is preferred, as aforementioned, for the discrimination to be conducted on a least errors basis.

Figs. 8a to ad are schematic illustrations of another test postal item 107 and the images resulting from each part of the code reader illustrated in Fig. 6.

As shown in Fig. 8a, the face of the mailpiece depicted is much improved (from the point of view of coding mark detection and discrimination) as compared to that of the mailpiece depicted in Fig. 7a in that the majority 109 of the face of the mailpiece is uncoloured, and clear of coloured printing.

However, the face of the mailpiece is not entirely clear of printing, and includes a printed message 111 which happens to partly overlie the region 113 of the mailpiece in which coding marks are normally printed - that region 113 being shown enlarged in Fig. 8b. As is visible from Fig. 8b, a coding mark has been printed on the mailpiece such that it partly overlies the message 11 I printed on the mailpiece.

Fig. 8c is an enlarged segment of an image of the face of the mailpiece 107 captured using the aforementioned first image capture module (the ultraviolet module) of the system as disclosed herein. The coding markimage depicted in Fig. 8c. is much improved, in terms of quality, as compared with that depicted in Fig. 7c., but there are still regions of the mark which are obscured by the printed message - although in this instance it is more the case that segments of individual bars of the mark are missing from the image, whereas in Fig. 7c entire sections of the mark were missing entirely from the Image.

Fig. ad is an enlarged segment of an image of the same mailpiece 107 captured using the aforementioned second image capture module (the LED module) of the system disclosed herein. From a comparison of Figs. 8c and ad, it is apparent that the segments of individual bars of the mark which are missing from the image depicted in Fig. 8c (because they are obscured by the printed message) have been revealed in the image captured by the LED imaging module.

What is also apparent, however, is that those elements of the mark which were printed over the white, and hence relatively highly reflective, part of the mailpiece have caused a degree of blooming (as above described) in the image capture device of the LED imaging module.

As a consequence, whilst it may be possible for the computer system aforementioned to decode the coding mark solely from the image depicted in Fig. ad, a much greater degree of accuracy is likely to be obtained by implementing the aforementioned least errors algorithm to at least notionally form a representative image comprised of the best parts of the two images depicted in Figs. 8c and 8d.

It will be apparent from the above that the teachings of the present invention provide a mechanism for improving the detection and discrimination of coding marks applied to mailpieces. As aforementioned, marks such as the four state bar code, or indeed any other type of mark, may be applied by IMPs in the course of a mailpiece sorting operation, or may alternatively be applied by any one or more of a number of different coding mark application devices.

In this connection, it should be noted that the detailed description provided herein is given by way of illustrative example only, and that modifications may be made without departing from the scope of the invention.

For example, it may be appropriate - having regard to the ink used to print the aforementioned coding marks - to use optical illumination and detection modules which operate at a different wavelength or range of wavelengths, or indeed to provide additional optical illumination and detection modules to the two disclosed above. In this context it should be noted that the scope of the invention pertains generally to the provision of at least two modules that are operable respectively to illuminate the face of a mailpiece and capture an image of a coding mark printed thereon, said two or more modules being configured to illuminate the mailpiece with different wavelengths or ranges of wavelengths of light.

It should also be noted that the teachings of the present invention are particularly useful when used to detect coding marks that have been provided on mailpieces using ink of the type disclosed in co-pending United Kingdom Patent Application No.0407330.0 (attorney reference: J45892GB)- the entire contents of which are incorporated herein by reference.

Claims (16)

1. A system for use in the detection of coding marks provided on the face of a mailpiece, the system comprising: at least two modules that are each operable to illuminate the face of a mailpiece, and to capture an image of the face of the mailpiece and any coding mark printed thereon, said two or more modules being configured to illuminate the mailpiece with different wavelengths, or ranges of wavelengths, of light.

2. A system according to Claim 1, further comprising means for locating and decoding coding marks included one or more of said captured images.

3. A system according to Claim 2, wherein said means comprises a computer system operable to compare an image of a coding mark derived from one said image with an image of a coding mark derived from another said Image.

4. A system according to Claim 3, wherein the computing system is operable to implement a least errors algorithm to generate, at least notionally, a composite image of the coding mark consisting of parts of the two images, as compared one with the other, which include the least errors.

5. A system according to any preceding claim, wherein a first of said modules includes an ultraviolet illumination means that is operable to illuminate the face of the mailpiece with ultraviolet light of 400 to 500 nm, more preferably 400 to 450 nm.

6. A system according to Claim 5, wherein said first module includes image capture means, such as a video camera, that is operable to capture an image of the face of the mailpiece.

7. A system according to any preceding claim, wherein a second of said modules includes an illumination means which is operable to illuminate the face of the mailpiece with light of substantially one wavelength.

8. A system according to Claim 7, wherein said second of said modules includes an LED light source as said illumination means.

9. A system according to Claim 8, wherein said LED light source comprises a plurality of LEDs.

10. A system according to any of claims 7 to 9 wherein the illumination means of said second module comprises a blue LED light source operable to illuminate the face of the mailpiece with light of a wavelength selected from 350 to 380 nm, preferably 365 nm.

11. A system according to any of Claims 7 to 10, wherein the second of said modules includes image capture means configured for capture of light substantially of said one wavelength.

12. A system according to Claim 11, wherein said image capture means comprises a CCD video camera.

13. A system according to Claim 12, wherein the video camera includes means for automatically adjusting the gain of the camera.

14. A sorting machine comprising a system as claimed in any of claims 1 to 13, including means for transporting mailpieces past each of said modules, preferably in turn, and means for sorting mailpieces in accordance with detected and decoded coding marks.

15. A sorting machine according to Claim 14 implemented as part of an integrated Mail Processing machine.

16. A system substantially as hereinbefore described with reference to the accompanying drawings.