CAMERA SYSTEM FOR A LABEL RECOGNITION DEVICE

Abstract

The invention relates to a camera system for a label recognition device, wherein the camera system is designed to recognize 1D and / or 2D label codes on objects that are moved in particular by a conveyor belt, wherein the camera system comprises a first camera unit with a first camera lens and a first image sensor and at least one processor. The camera system comprises at least a second camera unit with a second camera lens and a second image sensor. The first image sensor of the first camera unit is designed to record an image of an object in a first focus range and the second image sensor of the second camera unit is designed to record an image of an object in a second focus range, wherein the second focus range has a greater distance from the camera system than the first focus range.The processor is designed to process image data from the first image sensor and image data from the second image sensor.

Description

[0001] The invention relates to a camera system for a label recognition device, wherein the camera system is designed to recognize 1D and / or 2D label codes on objects that are moved in particular by a conveyor belt, wherein the camera system comprises a first camera unit with a first camera lens and a first image sensor and at least one processor.

[0002] Such camera systems are used, for example, to detect and identify objects such as packages on a conveyor belt in a logistics center. The distance between the object to be detected on the conveyor belt and the camera system can vary greatly. This can be caused by objects of significantly different heights when the camera system is positioned above the conveyor belt (i.e., a "top reading"). For camera systems positioned to the side of the conveyor belt (i.e., a "side reading"), wide conveyor belts and misaligned objects lead to significant differences in the distance.

[0003] The large differences in distance between the camera system and the object to be detected and identified place high demands on the depth of field and / or focus of the camera systems. The camera systems must be highly powerful and have a short response time, thus reacting quickly to ensure reliable reading and decoding of 1D and 2D label codes despite such diverse conditions.

[0004] Camera systems for such applications can be designed as line-scan cameras or as planar 2D cameras. Solutions for the above-mentioned requirements for line-scan cameras have so far aimed at combining very fast mechanical focus adjustment of the camera lens with a powerful processor. This enables reliable decoding and identification up to a conveyor belt speed of 4.5 m / s. Alternatively or additionally, an illumination device can be provided, whose strong illumination can achieve a large depth of field and thus compensate for different distances between the camera system and the object. In this case, the large depth of field is achieved by an aperture with a large f-number, which requires less light transmission.To increase the light transmission, the lighting devices therefore have a large number of powerful LEDs, which on the one hand increase the installation space of the camera system and on the other hand lead to high power consumption during operation of the camera system.

[0005] For reliable object detection and identification, camera systems with line scan cameras require mechanical focus adjustment and high computing power to process large amounts of data. However, mechanical focus adjustment is expensive, prone to defects, and complex to develop and integrate. Additionally, the inclusion of a high-power illumination device in the camera system may be necessary to increase and expand the depth of field. All of this makes these systems expensive, complex, prone to wear and tear, and prone to failure.

[0006] Dynamic focus adjustment has also been used in camera systems with 2D cameras to meet the above-mentioned requirements. However, the disadvantage here is that the focus adjustment occurs relatively slowly, which compromises the reliability of the camera system.

[0007] Another disadvantage, as with line scan cameras with mechanical focus adjustment, is that the distance between the camera system and the object must already be known in order to correctly adjust the focus. This distance information can be determined, for example, by a prior volume measurement of the object. The required distance information makes the setup and cabling of a system more complex and thus increases the system's costs. A further disadvantage arises from the need for object tracking to determine when the object is in the camera system's field of view.

[0008] It is therefore an object of the invention to provide an improved camera system for a label recognition device which is efficient, reliable, low-wear and cost-effective.

[0009] The object is achieved by a camera system having the features of claim 1 and in particular in that the camera system comprises at least a second camera unit with a second camera lens and a second image sensor, wherein the first image sensor of the first camera unit is designed to record an image of an object in a first focus range, wherein the second image sensor of the second camera unit is designed to record an image of an (e.g. the same and / or a different) object in a second focus range, wherein the second focus range has a greater distance from the camera system than the first focus range, and wherein the processor is designed to process image data of the first image sensor and image data of the second image sensor.

[0010] The camera system therefore has at least two separate camera units, each with its own camera lens and image sensors. The first camera unit is designed to record an image of an object in a first focus range that is at a shorter distance from the camera system. The first camera unit therefore records images, for example, in the close range of the camera system and at shorter distances between the camera system and the object. The second camera unit is designed to record an image of an object in a second focus range that is at a greater distance from the camera system. The second camera unit therefore records images, for example, in the middle or long range of the camera system and therefore at greater distances between the camera system and the object. The focus range is understood here as the spatial area in front of and behind the focus orFocal plane, in which the object is sharply imaged by the respective lens within the focal range. The distance to a respective focal range can be measured, in particular, from the camera system to the focal plane of the respective focal range or from the camera system to the point of the focal range closest to the camera system.

[0011] The processor is configured to process image data from the first image sensor, which maps the close-up range of the camera system, and image data from the second image sensor, which maps the medium or long-range range. Processing occurs as soon as the image data from the first image sensor or the second image sensor is present and available for processing by the processor. The processing of the image data from the respective image sensors is preferably completely independent of one another. The processing of the image data from the first image sensor and the second image sensor can thus take place simultaneously in the processor.

[0012] The processor can, for example, comprise an FPGA (Field Programmable Gate Array), which has a dedicated processing pipeline for the image data for each image sensor. The processor can also comprise an application processor, which is coupled to the FPGA, for example, via PCI Express (PCIe). The application processor recognizes the label codes in the image data from the image sensors. The application processor can, for example, be a processor from the i.MX 6, i.MX 8, or i.MX 9 series from NXP.

[0013] Since the camera system has at least two image sensors, each covering, for example, the close-up range on the one hand and the medium or long-range range on the other, the camera system has a large depth of field, which results from the combination of the first focus range of the first camera unit and the second focus range of the second camera unit. The camera system thus very reliably captures objects and images them sharply, although large differences in the respective distances between the camera system and the object are possible.

[0014] Because the camera system does not have to react to different distances depending on the situation, no manual or mechanical adjustment of the focus or aperture in the respective camera lenses is necessary to achieve the large depth of field. Therefore, the camera system eliminates the need for moving parts for focus adjustment, which reduces the camera system's susceptibility to failure. Furthermore, the camera system does not require a high-intensity lighting device, as is necessary for camera systems that achieve a large depth of field and a large depth of field by increasing the aperture.

[0015] The camera system according to the invention is thus low-wear, efficient and cost-effective and enables reliable detection and identification of objects.

[0016] Advantageous embodiments of the invention can be found in the dependent claims, the description and the drawing.

[0017] According to one embodiment of the invention, the first focus range and the second focus range are preset. The presetting is selected such that the spatial position of the focus range and / or the size (i.e. the extent) of the first and second focus ranges are adapted to the distance relationships between the conveyor belt and the position of the camera system. In this case, the first focus range and the second focus range can be set such that the distance range of the first focus range is flush and without interruption with the distance range of the second focus range. Alternatively, the focus ranges can also be set such that the respective distance ranges have an overlap or intersection.As a further alternative, the first and second focus ranges may be set such that the respective distance ranges are not adjacent to each other and form two separate distance ranges separated by an interruption.

[0018] In addition to the options mentioned for the distance ranges of the focus areas, it is possible for the focus areas to be spatially spaced or partially or completely overlapping each other. Spatial spacing is possible (despite, for example, focus areas being adjacent to each other solely in terms of distance) if the camera units are spaced apart. The camera units can each be aligned so that they face in parallel directions.

[0019] According to one embodiment of the invention, the first focal range and the second focal range each remain unchanged during operation of the camera system and each have the preset value. During operation of the camera system, no adjustment of the focal ranges via an aperture or focus setting is necessary, since the camera system does not have to react situationally to different distances between the object and the camera system. The first and second camera lenses can thus each be designed as a fixed-focus & fixed-aperture camera lens. Such camera lenses can be designed very compactly and are also cost-effective. The compact camera lenses enable a compact design of the camera system, which reduces its space requirements and also enables a more compact design of the label recognition device.

[0020] According to one embodiment of the invention, the first focal region has a greater depth of field than the second focal region, or vice versa. This allows the second camera unit to capture sharp images of objects not only at greater distances, but also over a wider distance range, thus capturing objects in the medium and long range even more reliably.

[0021] According to one embodiment of the invention, the first image sensor has a first image resolution that is lower than a second image resolution of the second image sensor. The first image sensor for the close range thus has a lower image resolution than the second image sensor for the medium and long range, which has a higher image resolution due to the greater distance between the object and the camera system. Due to the lower image resolution of the first image sensor, the camera system only requires a small camera lens, which meets low resolution requirements. Secondly, the low-resolution image data of the first image sensor also place lower demands on the computing power of the processor for processing this image data. Both of these factors contribute significantly to reducing the costs of the camera system.

[0022] According to one embodiment of the invention, the first image sensor has a first light-sensitive area that is the same size as a second light-sensitive area of ​​the second image sensor. The first image sensor can thus image a larger aperture angle in the near field than the second image sensor, which images the medium and far field. The light-sensitive area can be formed, for example, by a CMOS and / or CCD image sensor.

[0023] Alternatively, it is also possible for the first image sensor to have a first light-sensitive area that is smaller than a second light-sensitive area of ​​the second image sensor. Since the first image sensor images the near field, its light-sensitive area can be selected to be smaller than the light-sensitive area of ​​the second image sensor, which images the medium and far field.

[0024] According to one embodiment of the invention, the first camera unit has a first frame rate that is higher than a second frame rate of the second camera unit. The first camera unit for the close-range runs at a higher frame rate in order to be able to capture all objects with a small distance between the object and the camera system at a fast conveyor belt speed. Since the first image sensor can have a lower image resolution, the image data from the first camera unit can be processed with low demands on the processor's computing power. The second camera unit for the medium and long-range can run at a low frame rate because the objects are in the camera unit's field of view for longer. This also results in low demands on the processor's computing power for processing the image data from the second image sensor for the medium and long-range.

[0025] Furthermore, the computing power required to search for and identify label codes in the image data is reduced, which can be very challenging for the system when dealing with large images and correspondingly large data volumes. The two camera units with different image resolutions also simplify and facilitate this process.

[0026] According to one embodiment of the invention, the first camera unit has a first frame rate that is equal to a second frame rate of the second camera unit. In other words, image capture between the first camera unit and the second camera unit is synchronized, with the two camera units capturing images simultaneously using the respective image sensors. In particular, the first camera unit and the second camera unit can run at a low frame rate, resulting in low computing power requirements of the processor for processing the image data from the first and second image sensors.

[0027] According to one embodiment of the invention, the camera system additionally comprises an illumination device configured to illuminate the object. The illumination device serves solely to illuminate the object and does not need to compensate for the light loss caused by a high-f-number aperture for the purpose of increasing the depth of field. The illumination device can therefore have a moderate luminous intensity, thereby reducing its power consumption and the cost of the camera system.

[0028] According to one embodiment of the invention, the illumination device periodically emits light according to a clock rate, wherein the clock rate is synchronized with the first frame rate and / or the second frame rate. Particularly in the case of synchronized image recordings with identical frame rates, synchronizing the clock rate with the then single frame rate offers the advantage that a single light pulse from the illumination device is sufficient to simultaneously illuminate an object captured by the first camera unit and an object captured by the second camera unit. This further reduces the costs of the camera system.

[0029] According to one embodiment of the invention, the camera system additionally comprises a third camera unit with a third camera lens and a third image sensor, wherein the third image sensor of the third camera unit is designed to capture an image of an object in a third focal range, wherein the third focal range has a greater distance from the camera system than the second focal range, and wherein the processor is designed to process image data from the third image sensor. In this embodiment, for example, the near range can be covered by the first camera unit, the middle range by the second camera unit, and the far range by the third camera unit. This may enable better coordination of the respective focal ranges and easier coverage of the entire relevant distance range between the object and the camera system.

[0030] According to one embodiment of the invention, the third focus range is preset and remains unchanged during operation of the camera system. Like the first and second camera lenses, the third camera lens can also be designed as a fixed-focus and fixed-aperture lens. The third focus range can be set such that the distance ranges of the first focus range, the second focus range, and the third focus range are each flush with one another. However, overlaps of the respective distance ranges or interruptions between adjacent distance ranges are also possible.

[0031] According to one embodiment of the invention, the third focal region has a depth of field that is at least equal to the depth of field of the second focal region. The third camera unit can thus sharply image objects at greater distances and within a wide distance range, making it particularly suitable for capturing objects in the far field of the camera system. Alternatively, the first, second, and third focal regions can each have different depths of field, in particular, greater depths of field with increasing distance from the camera system.

[0032] According to one embodiment of the invention, the third image sensor has a third image resolution that is greater than the first image resolution of the first image sensor, in particular, the third image resolution is at least equal to the second image resolution of the second image sensor. In particular, the third image sensor can be designed identically to the second image sensor.

[0033] According to one embodiment of the invention, the third image sensor has a third light-sensitive area that is at least as large as the second light-sensitive area of ​​the second image sensor. In particular, the third image sensor can be designed identically to the second image sensor.

[0034] According to one embodiment of the invention, the third camera unit has a third refresh rate that is lower than a first refresh rate of the first camera unit, in particular, the third refresh rate being at most equal to the second refresh rate. The third camera unit, for example for long-range applications, captures objects at greater distances between the object and the camera system. The third camera unit can therefore run at a lower refresh rate because the objects remain in the camera unit's field of view for a longer period.

[0035] According to one embodiment of the invention, the third camera unit has a third refresh rate that is equal to the first refresh rate of the first camera unit and the second refresh rate of the second camera unit. In other words, image recording between the first camera unit, the second camera unit, and the third camera unit is synchronized, with all three camera units recording images on the respective image sensors simultaneously.

[0036] According to one embodiment of the invention, the clock rate of the illumination device is synchronized with the first refresh rate and / or the second refresh rate and / or the third refresh rate. Particularly in the case of synchronized image recordings with identical refresh rates, synchronizing the clock rate with the then single refresh rate offers the advantage that a single light pulse from the illumination device is sufficient to simultaneously illuminate an object captured by the first camera unit, an object captured by the second camera unit, and an object captured by the third camera unit. This further reduces the costs of the camera system.

[0037] According to one embodiment of the invention, the respective camera unit is designed as a line-scan camera or a 2D camera. The camera system can be implemented with both line-scan cameras and 2D cameras and enables cost-effective and reliable object detection and identification for both camera types.

[0038] The object is further achieved by a label recognition device configured to identify and decode 1D and / or 2D label codes on objects moving along a conveyor belt, comprising an above-mentioned camera system. The 1D and / or 2D label codes can be, for example, barcodes, QR codes, destination codes (for letters), Data Matrix 2D codes, or the like. The conveyor belt can be a component of the label recognition device.

[0039] The camera system is designed to capture images of the objects moving on the conveyor belt in particular on the respective image sensors and to process them in a processor.

[0040] Furthermore, the statements regarding the camera system according to the invention apply accordingly to the label recognition device according to the invention, especially with regard to advantages and embodiments. It is also understood that all features mentioned herein can be combined with one another, unless explicitly stated otherwise.

[0041] The invention is explained below merely by way of example with reference to the figures. Fig. 1 shows a schematic side view of a label recognition device with an embodiment of a camera system according to the invention, Fig. 2 shows a schematic bottom view of the embodiment of the camera system of the Fig.1, Figs. 3 to 8 show different embodiments of the processor of the camera system.

[0042] Fig. 1 shows a schematic side view of a label recognition device 10 with an embodiment of a camera system 12 according to the invention. The camera system 12 is arranged above a conveyor belt 14 on which several packages 16 (ie objects) are moved in the conveying direction 18.

[0043] The camera system 12 comprises a first camera unit 20 with a first image sensor 22 and a first camera lens (not shown), and a second camera unit 24 with a second image sensor 26 and a second camera lens (not shown). The first camera unit 20 and the second camera unit 24 are each oriented in the direction of the conveyor belt 14. The camera system 12 further comprises a processor 28, which is configured to process image data from the first image sensor 22 and the second image sensor 26. The first and second camera lenses are each configured as a fixed-focus and fixed-aperture lens, wherein the respective focus and the respective depth of field are preset and retain the preset values ​​unchanged during operation of the label recognition device 10 and the camera system 12.

[0044] The first image sensor 22 of the first camera unit 20 is configured to capture an image of a package 16 in a first focus area 30, while the second image sensor 26 of the second camera unit 24 is configured to capture an image of a package 16 in a second focus area 32. The second focus area 32 is at a greater distance from the camera system than the first focus area 30. The first camera unit 20 thus captures an image of a package 16 in a close-up range, whereas the second camera unit 24 captures an image of a package 16 in a medium and long-range range. Near, medium, and long-range each refer to the distance between the camera system 12 and the respective packages 16 moving on the conveyor belt 14. As in Fig. 1As shown, the distance range of the first focus range 30 in the near range is flush with the distance range of the second focus range 32 in the middle and far range. However, embodiments are also possible that provide an overlap of the distance ranges or an interruption between the respective distance ranges.

[0045] Fig. 2 shows a schematic view from below of the embodiment of the camera system 12 of the Fig. 1 . The shown underside of the camera system 12 is in the label recognition device 10 of the Fig. 1 aligned in the direction of the conveyor belt 14. The first image sensor 22 for the near range has a lower image resolution and a smaller light-sensitive area than the second image sensor 26 for the medium and long range. Alternatively, the light-sensitive areas of the first image sensor 22 and the second image sensor 26 can also be the same size. As shown in Fig. 2As shown, the camera system 12 also includes an illumination device 34 formed by LEDs 36 arranged rectangularly around the first image sensor 22 and the second image sensor 26 on the underside of the camera system 12.

[0046] In order to be able to capture all packages 16 with a small distance between the package 16 and the camera system 12 at a fast belt speed of the conveyor belt 14, the first camera unit 20 has a first frame rate that is higher than a second frame rate of the second camera unit 24. Since the first image sensor 22 has a lower image resolution than the second image sensor 26, the image data from the first camera unit 20 can be processed with low demands on the computing power of the processor 28 despite the higher frame rate. The second camera unit 24, which captures and images the medium and long-range areas, runs at a low frame rate because the packages 16 are in the field of view of the second camera unit 24 for a longer period of time. This also results in low demands on the computing power of the processor 28 for processing the image data from the second image sensor 26 in the medium and long-range areas.To illuminate the packages 16 on the conveyor belt 14, the LEDs 36 of the lighting device 34 periodically emit light according to a clock rate, wherein the clock rate can be synchronized with the first refresh rate and / or the second refresh rate.

[0047] The processor 28 is configured to process image data from the first image sensor 22 and image data from the second image sensor 26. Processing occurs as soon as the image data from the first image sensor 22 or the second image sensor 26 is present and available for processing by the processor 28. The image data from the respective image sensors 22 and 26 are preferably processed completely independently of one another, allowing the image data from the first image sensor 22 and the second image sensor 26 to be processed simultaneously in the processor 28.

[0048] Since the camera system 12 has two image sensors 22 and 26, each covering the near range and the medium or far range, the camera system 22 has a large focal range resulting from the combination of the first focal range 30 of the first camera unit 20 and the second focal range 32 of the second camera unit 24. The camera system 12 thus very reliably detects packages 16 that exhibit large differences in the respective distances between the camera system 12 and the package 16.

[0049] Since the camera system 12 does not have to react to different distances depending on the situation, no manual or mechanical adjustment of the focus or aperture of the respective camera lenses is necessary to achieve the large depth of field. The camera system 12 therefore has no moving parts for focus adjustment, which reduces the susceptibility of the camera system 12 to defects.

[0050] The camera system 12 according to the invention is thus low-wear, efficient and cost-effective and enables reliable detection and identification of objects such as those in the Fig. 1 packages shown 16.

[0051] Fig. 3 shows a first embodiment of a processor 28 of the camera system 12 of the Fig. 1 and 2 The processor 28 comprises an FPGA (Field Programmable Gate Array), which has a separate processing pipeline for the image data for each image sensor 22, 26. The processor 28 further comprises an application processor, which is coupled to the FPGA, for example, via PCI Express (PCIe), wherein the application processor detects the label codes in the image data from the image sensors 22, 26.

[0052] Fig. 4 shows a second embodiment of a processor 28 of the camera system 12 of the Fig. 1 and 2 In contrast to the design of the Fig. 3This embodiment has two FPGAs (FPGA1 and FPGA2), each with its own processing pipeline for the image data for each image sensor 22, 26. The two FPGAs are each coupled via PCIe to one of two application processors for recognizing the label codes in the image data from the image sensors 22, 26. The application processors can be configured to exchange the respective results of the label code recognition with each other.

[0053] Figs. 5 and 6 show a third and fourth embodiment of a processor 28 of the camera system 12 of the Fig. 1 and 2 , in which the FPGA and the application processor are combined in a Multi-Processor System on Chip (MPSoC) module.

[0054] Figs. 7 and 8 show a fifth and sixth embodiment of a processor 28 of the camera system 12 of the Fig. 1 and 2, in which the combination of FPGA and application processor was replaced by an Artificial Intelligence (AI) processor. Reference symbol

[0055] 10Label recognition device 12Camera system 14Conveyor belt 16Package 18Conveying direction 20First camera unit 22First image sensor 24Second camera unit 26Second image sensor 28Processor 30First focus area 32Second focus area 34Illumination device 36LED

Claims

1. Camera system (12) for a label recognition device (10), wherein the camera system (12) is designed to recognize 1D and / or 2D label codes on objects (16) which are moved in particular by a conveyor belt (14), wherein the camera system (12) comprises a first camera unit (20) with a first camera lens and a first image sensor (22) and at least one processor (28), characterized in thatthe camera system (12) comprises at least a second camera unit (24) with a second camera lens and a second image sensor (26), wherein the first image sensor (22) of the first camera unit (20) is designed to record an image of an object (16) in a first focus area (30), wherein the second image sensor (26) of the second camera unit (24) is designed to record an image of an object (16) in a second focus area (32), wherein the second focus area (32) has a greater distance from the camera system (12) than the first focus area (30), and wherein the processor (28) is designed to process image data from the first image sensor (22) and image data from the second image sensor (26).

2. Camera system (12) according to claim 1, wherein the first focus range (30) and the second focus range (32) are preset.

3. Camera system (12) according to claim 2, wherein the first focus range (30) and the second focus range (32) each remain unchanged during operation of the camera system (12) and each have the preset value.

4. Camera system (12) according to one of the preceding claims, wherein the first focus area (30) has a greater depth of field than the second focus area (32).

5. Camera system (12) according to one of the preceding claims, wherein the first image sensor (22) has a first image resolution which is smaller than a second image resolution of the second image sensor (26).

6. Camera system (12) according to one of the preceding claims, wherein the first image sensor (22) has a first light-sensitive area which is the same size as a second light-sensitive area of ​​the second image sensor (26).

7. Camera system (12) according to one of the preceding claims, wherein the first camera unit (20) has a first refresh rate that is greater than a second refresh rate of the second camera unit (24), or wherein the first camera unit (20) has a first refresh rate that is equal to a second refresh rate of the second camera unit (24).

8. Camera system (12) according to one of the preceding claims, additionally comprising an illumination device (34) which is designed to illuminate the object (16), wherein the illumination device (34) periodically emits light according to a clock rate which is synchronized with the first frame rate and / or the second frame rate.

9. Camera system (12) according to one of the preceding claims, additionally comprising a third camera unit with a third camera lens and a third image sensor, wherein the third image sensor of the third camera unit is designed to record an image of an object (16) in a third focus range, wherein the third focus range has a greater distance from the camera system (12) than the second focus range (32), and wherein the processor (28) is designed to process image data of the third image sensor, in particular wherein the third focus range is preset and remains unchanged during operation of the camera system (12) and has the preset value.

10. Camera system (12) according to claim 9, wherein the third focus area has a depth of field that is at least equal to the depth of field of the second focus area (32), and / or wherein the third image sensor has a third image resolution that is greater than the first image resolution of the first image sensor (22), in particular wherein the third image resolution is at least equal to the second image resolution of the second image sensor (26).

11. Camera system (12) according to claim 9 or 10, wherein the third light-sensitive area is at least as large as the second light-sensitive area of ​​the second image sensor (26).

12. Camera system (12) according to one of claims 9 to 11, wherein the third camera unit has a third refresh rate which is smaller than a first refresh rate of the first camera unit (20), in particular wherein the third refresh rate is at most equal to the second refresh rate of the second camera unit (24), or wherein the third camera unit has a third refresh rate which is equal to the first refresh rate of the first camera unit (20) and the second refresh rate of the second camera unit (24).

13. Camera system (12) according to one of claims 9 to 12, wherein the clock rate of the illumination device (34) is synchronized with the first refresh rate and / or the second refresh rate and / or the third refresh rate.

14. Camera system (12) according to one of the preceding claims, wherein the respective camera unit (22, 24) is designed as a line camera or as a 2D camera.

15. A label recognition device (10) configured to identify and decode 1D and / or 2D label codes on objects (16) being moved by a conveyor belt (14), comprising a camera system (12) according to any one of claims 1 to 18.