技术领域technical field
本发明涉及一种测距系统，具体地，涉及一种具有动态曝光时间的光学测距系统。The invention relates to a ranging system, in particular to an optical ranging system with dynamic exposure time.
背景技术Background technique
光学测距系统可采用三角测量方法计算对象的距离。例如，光学测距器系统可包含光源以及照相机。所述光源朝向待测物投射光线，所述照相机接收来自所述待测物的反射光以形成图像帧。当所述光源与所述照相机的空间关系为已知时，根据所述图像帧中的对象图像位置即能够根据三角测量计算出所述待测物的距离。Optical ranging systems calculate the distance to objects using triangulation methods. For example, an optical rangefinder system may include a light source as well as a camera. The light source projects light toward the object under test, and the camera receives reflected light from the object under test to form an image frame. When the spatial relationship between the light source and the camera is known, the distance of the object under test can be calculated according to the position of the object image in the image frame according to triangulation.
然而，当空间中同时存在不同距离的多个待测物时，近距离的待测物可能会有过曝光(over exposure)的情形，而远距离的待测物可能会有曝光不足(under exposure)的情形，光学测距系统的计算精确度可能会因此而降低。尤其，当远距离待测物的曝光不足时，会出现无法计算远距离待测物的对象距离的问题。However, when there are multiple UUTs with different distances in the space at the same time, the near-distance UUTs may have over exposure, while the far-distance UUTs may have underexposure. ), the calculation accuracy of the optical distance measuring system may be reduced. In particular, when the exposure of the distant object under test is insufficient, there will be a problem that the object distance of the distant object cannot be calculated.
发明内容Contents of the invention
有鉴于此，本发明提出一种可在图像帧中同时保留远近待测物信息的光学测距系统，以增加计算精确度。In view of this, the present invention proposes an optical ranging system that can simultaneously retain the information of the far and near objects to be measured in the image frame, so as to increase the calculation accuracy.
本发明提供一种使用时间复用曝光机制的光学测距系统。The present invention provides an optical ranging system using a time-multiplexed exposure mechanism.
本发明提供一种使用时间复用曝光机制并可降低耗能的光学测距系统。The invention provides an optical ranging system which uses a time-multiplexed exposure mechanism and can reduce energy consumption.
本发明提供一种光学测距系统，包含光源、图像传感器以及处理单元。所述光源以操作频率发光。所述图像传感器以第一曝光时间在所述光源点亮时获取第一亮图像及在所述光源熄灭时获取第一暗图像并以第二曝光时间在所述光源点亮时获取第二亮图像及在所述光源熄灭时获取第二暗图像，其中所述第二曝光时间大于所述第一曝光时间。所述处理单元用于接收所述第一亮图像、所述第一暗图像、所述第二亮图像及所述第二暗图像，并根据所述第一暗图像的第一平均亮度调整所述第一曝光时间并根据所述第二暗图像的第二平均亮度调整所述第二曝光时间。The invention provides an optical ranging system, which includes a light source, an image sensor and a processing unit. The light source emits light at an operating frequency. The image sensor acquires a first bright image when the light source is turned on with a first exposure time and a first dark image when the light source is turned off, and acquires a second bright image when the light source is turned on with a second exposure time. image and acquire a second dark image when the light source is turned off, wherein the second exposure time is greater than the first exposure time. The processing unit is configured to receive the first bright image, the first dark image, the second bright image, and the second dark image, and adjust the adjusting the first exposure time and adjusting the second exposure time according to the second average brightness of the second dark image.
本发明还提供一种光学测距系统，包含光源、图像传感器以及处理单元。所述光源以操作频率发光。所述图像传感器以第一曝光时间在所述光源点亮时获取第一亮图像及在所述光源熄灭时获取第一暗图像并以第二曝光时间在所述光源点亮时获取第二亮图像及在所述光源熄灭时获取第二暗图像，其中所述第二曝光时间大于所述第一曝光时间。所述处理单元用于接收所述第一亮图像、所述第一暗图像、所述第二亮图像及所述第二暗图像，并根据所述第二暗图像中对象图像尺寸调整所述第二曝光时间。The invention also provides an optical ranging system, which includes a light source, an image sensor and a processing unit. The light source emits light at an operating frequency. The image sensor acquires a first bright image when the light source is turned on with a first exposure time and a first dark image when the light source is turned off, and acquires a second bright image when the light source is turned on with a second exposure time. image and acquire a second dark image when the light source is turned off, wherein the second exposure time is greater than the first exposure time. The processing unit is configured to receive the first bright image, the first dark image, the second bright image, and the second dark image, and adjust the object image size according to the second dark image. Second exposure time.
本发明还提供一种光学测距系统，包含图像传感器以及处理单元。所述图像传感器以参考曝光时间获取参考暗图像、以第一曝光时间获取第一图像并以第二曝光时间获取第二图像，其中所述第二曝光时间大于所述第一曝光时间。所述处理单元用于当判断所述参考暗图像中存在对象图像时，控制所述图像传感器交替地以所述第一曝光时间获取所述第一图像并以所述第二曝光时间获取所述第二图像；以及当判断所述参考暗图像中不存在任何对象图像时，控制所述图像传感器以所述参考曝光时间获取另一参考暗图像。The invention also provides an optical ranging system, which includes an image sensor and a processing unit. The image sensor acquires a reference dark image with a reference exposure time, a first image with a first exposure time, and a second image with a second exposure time, wherein the second exposure time is greater than the first exposure time. The processing unit is configured to control the image sensor to alternately acquire the first image with the first exposure time and acquire the image with the second exposure time when it is judged that there is an object image in the reference dark image. a second image; and when it is judged that there is no object image in the reference dark image, controlling the image sensor to acquire another reference dark image with the reference exposure time.
为了让本发明的上述和其它目的、特征和优点能更明显，下文将配合所附图示，详细说明如下。此外，在本发明的说明中，相同的元件以相同的符号表示，于此先述明。In order to make the above and other objects, features and advantages of the present invention more apparent, the detailed description is as follows with reference to the accompanying drawings. In addition, in the description of the present invention, the same components are denoted by the same symbols, and will be described earlier.
附图说明Description of drawings
图1为本发明一实施例的光学测距系统的框图。FIG. 1 is a block diagram of an optical ranging system according to an embodiment of the present invention.
图2为本发明一实施例的光学测距系统示意图。FIG. 2 is a schematic diagram of an optical ranging system according to an embodiment of the present invention.
图3为本发明第一实施例的光学测距系统的测距方法流程图。FIG. 3 is a flow chart of a ranging method of the optical ranging system according to the first embodiment of the present invention.
图4A为本发明第一实施例的光学测距系统的操作示意图。FIG. 4A is a schematic diagram of the operation of the optical ranging system according to the first embodiment of the present invention.
图4B为本发明第一实施例的光学测距系统的另一操作示意图。FIG. 4B is another schematic diagram of the operation of the optical ranging system according to the first embodiment of the present invention.
图5为本发明第二实施例的光学测距系统的操作示意图。FIG. 5 is a schematic diagram of the operation of the optical ranging system according to the second embodiment of the present invention.
图6为本发明第二实施例的光学测距系统中阈值设定的示意图。FIG. 6 is a schematic diagram of threshold setting in the optical ranging system according to the second embodiment of the present invention.
图7为本发明第二实施例的光学测距系统的另一操作示意图。FIG. 7 is another schematic diagram of the operation of the optical ranging system according to the second embodiment of the present invention.
图8为本发明第二实施例的光学测距系统中决定对象图像尺寸的示意图。FIG. 8 is a schematic diagram of determining the size of an object image in the optical ranging system according to the second embodiment of the present invention.
图9A～9B为本发明第三实施例的光学测距系统的操作示意图。9A-9B are schematic diagrams of the operation of the optical ranging system according to the third embodiment of the present invention.
具体实施方式detailed description
如图1所示，其为本发明一实施例的光学测距系统的框图。光学测距系统1包含图像传感器11以及处理单元13。所述图像传感器11优选为主动式图像传感器，例如互补金属氧化物半导体(CMOS)图像传感器，但并不限于此，其可改变获取图像F时的曝光时间(exposure time)(举例详述于后)。As shown in FIG. 1 , it is a block diagram of an optical ranging system according to an embodiment of the present invention. The optical ranging system 1 includes an image sensor 11 and a processing unit 13 . The image sensor 11 is preferably an active image sensor, such as a complementary metal-oxide-semiconductor (CMOS) image sensor, but is not limited thereto, and it can change the exposure time (exposure time) when the image F is acquired (for example, it will be described in detail later. ).
所述处理单元13例如可为数字信号处理器(DSP)、单片机(MCU)、中央处理器(CPU)、特定用途集成电路(ASIC)等，用于接收所述图像传感器11所输出的图像F以进行后续处理，并控制所述图像传感器11的图像获取。某些实施例中，所述处理单元13可包含曝光控制单元131、复用模块133以及距离计算单元135；其中，所述曝光控制单元131、所述复用模块133及所述距离计算单元135为所述处理单元13内的数据处理单元，其可以软件或硬件的方式实现，并无特定限制。可以理解的是，虽然图1中将所述处理单元13分割为不同工作模块以便于说明，所述处理单元13内的各工作模块所执行的所有功能，均可以说是由所述处理单元13所执行的。The processing unit 13 can be, for example, a digital signal processor (DSP), a single-chip microcomputer (MCU), a central processing unit (CPU), an application-specific integrated circuit (ASIC), etc., for receiving the image F outputted by the image sensor 11. to perform subsequent processing, and to control the image acquisition of the image sensor 11 . In some embodiments, the processing unit 13 may include an exposure control unit 131, a multiplexing module 133, and a distance calculation unit 135; wherein, the exposure control unit 131, the multiplexing module 133, and the distance calculation unit 135 It is a data processing unit in the processing unit 13, which can be implemented in the form of software or hardware, and there is no specific limitation. It can be understood that although the processing unit 13 is divided into different working modules in FIG. executed.
所述曝光控制单元131用于控制所述图像传感器11以不同曝光时间获取不同图像F的所有图像区域(即一张图像对应一个曝光时间)。所述复用模块133利用时间复用处理所述处理单元13所接收的图像F并产生待计算图像Fm(例如后述的组合图像)。所述距离计算单元135则利用预设算法根据所述待计算图像Fm计算至少一个对象距离，例如利用三角测量方法(triangulation)计算所述对象距离。The exposure control unit 131 is used to control the image sensor 11 to acquire all image regions of different images F with different exposure times (ie one image corresponds to one exposure time). The multiplexing module 133 uses time multiplexing to process the image F received by the processing unit 13 and generates an image Fm to be calculated (such as a combined image described later). The distance calculating unit 135 uses a preset algorithm to calculate at least one object distance according to the image to be calculated Fm, for example, uses a triangulation method (triangulation) to calculate the object distance.
如图2所示，其为本发明一实施例的光学测距系统的示意图。光学测距系统1还可包含光源15，用于投射二维光区域(例如具有预设宽度的光线条)至待测物9；其中，所述光源15例如可为相干光源、部分相干光源或非相干光源，并无特定限制，其用于发出可辨识光谱，例如可见光或不可见光。必须说明的是，虽然图2中所述光源15所投射的二维光区域显示为非连续，然其仅用以说明，并非用以限定本发明，所述光源15可以扫描的方式投射所述二维光区域或直接投射一个二维光区域。As shown in FIG. 2 , it is a schematic diagram of an optical ranging system according to an embodiment of the present invention. The optical ranging system 1 may also include a light source 15 for projecting a two-dimensional light area (such as a light line with a preset width) to the object 9 to be measured; wherein, the light source 15 may be, for example, a coherent light source, a partially coherent light source or An incoherent light source, without particular limitation, that emits a discernible spectrum, such as visible light or invisible light. It must be noted that although the two-dimensional light area projected by the light source 15 in FIG. 2D light area or directly cast a 2D light area.
所述图像传感器11接收来自所述待测物9的反射光后，产生包含反射光图像I9的图像F，并将该图像F传送至所述处理单元13。所述图像传感器11例如包含像素矩阵，其由多个像素排列而成，而所述图像F则为所述多个像素所输出的灰度值矩阵数据。After the image sensor 11 receives the reflected light from the object under test 9 , it generates an image F including the reflected light image I9 , and transmits the image F to the processing unit 13 . The image sensor 11 includes, for example, a pixel matrix, which is formed by a plurality of pixels, and the image F is the gray value matrix data output by the plurality of pixels.
所述处理单元13首先利用本发明的复用机制(举例详述于后)根据所述图像F产生待计算图像Fm，并根据所述待计算图像Fm计算至少一个对象距离D；其中，所述待计算图像Fm同样包含反射光图像I9。更具体地，所述待计算图像Fm的不同图像区域所对应的多个曝光时间的至少一部分可彼此不同(举例详述于后)，以使每一个图像区域中的反射光图像I9的亮度适于计算所述至少一个对象距离D。此外，在某些实施例中，所述处理单元13可有线或无线地输出所述待计算图像Fm以供外部装置进行后续处理，例如输出至外部主机(host)。The processing unit 13 first utilizes the multiplexing mechanism of the present invention (for example to be described in detail later) to generate an image Fm to be calculated according to the image F, and calculate at least one object distance D according to the image Fm to be calculated; wherein, the The image to be calculated Fm also includes the reflected light image I9. More specifically, at least a part of the multiple exposure times corresponding to different image regions of the image to be calculated Fm may be different from each other (for example, details will be described later), so that the brightness of the reflected light image I9 in each image region is suitable. for calculating the at least one object distance D. In addition, in some embodiments, the processing unit 13 may output the image Fm to be calculated by wire or wirelessly for subsequent processing by an external device, such as outputting to an external host (host).
在一实施例中，所述处理单元13可包含存储单元(未绘示)，用以储存对照表，其包含反射光图像I9的位置与对象距离D的关系。藉此，当所述处理单元13求得所述待计算图像Fm中反射光图像I9的位置后，即可直接对照所述对照表以求得至少一个对象距离D；其中，所述对照表根据所述光源15与所述图像传感器11的空间关系(例如距离L)以及所述光源15的照明角度所计算，并事先储存于所述存储单元中。在另一实施例中，所述处理单元13的存储单元可储存有距离算法而非对照表，当求得所述待计算图像Fm中反射光图像I9的位置后，即可利用所述距离算法计算出至少一个对象距离D。In one embodiment, the processing unit 13 may include a storage unit (not shown) for storing a comparison table, which includes the relationship between the position of the reflected light image I9 and the distance D of the object. In this way, after the processing unit 13 obtains the position of the reflected light image I9 in the image to be calculated Fm, it can directly compare the comparison table to obtain at least one object distance D; wherein, the comparison table is based on The spatial relationship between the light source 15 and the image sensor 11 (such as the distance L) and the illumination angle of the light source 15 are calculated and stored in the storage unit in advance. In another embodiment, the storage unit of the processing unit 13 may store a distance algorithm instead of a look-up table. After obtaining the position of the reflected light image I9 in the image Fm to be calculated, the distance algorithm can be used At least one object distance D is calculated.
本发明说明中，由于所述光源15用于投射二维光区域，因此所述图像传感器11所输出的图像F中包含线性反射光图像I9，所述处理单元13可同时计算多个对象距离(例如，不同待测物对应不同的反射光图像的区段且位于不同位置)，故具有较好的适用性。最后，所述处理单元13将所计算的所述至少一个对象距离D输出以进行相应控制，例如输出至主机或计算机系统；其中，所述对象距离D对应的控制功能则根据不同应用而定。In the description of the present invention, since the light source 15 is used to project a two-dimensional light area, the image F output by the image sensor 11 includes a linear reflected light image I9, and the processing unit 13 can simultaneously calculate multiple object distances ( For example, different objects to be tested correspond to different sections of the reflected light image and are located at different positions), so it has better applicability. Finally, the processing unit 13 outputs the calculated at least one object distance D for corresponding control, for example, to a host computer or a computer system; wherein, the control function corresponding to the object distance D depends on different applications.
如图3所示，其为本发明第一实施例的光学测距系统的测距方法流程图，包含下列步骤：以第一曝光时间获取第一图像(步骤S31)；以第二曝光时间获取第二图像(步骤S32)；将所述第一图像分割为多个第一图像区域并计算所述多个第一图像区域中每一者的第一信号特征(步骤S33)；将所述第二图像分割为多个第二图像区域并计算所述多个第二图像区域中每一者的第二信号特征(步骤S34)；比较所述多个第一信号特征与所述多个第二信号特征(步骤S35)；以及将所述第一信号特征大于所述第二信号特征的所述多个第一图像区域与所述第二信号特征大于所述第一信号特征的所述多个第二图像区域组合成组合图像(步骤S36)。As shown in Figure 3, it is a flowchart of the ranging method of the optical ranging system according to the first embodiment of the present invention, comprising the following steps: acquiring the first image with the first exposure time (step S31); acquiring with the second exposure time The second image (step S32); the first image is divided into a plurality of first image regions and the first signal feature of each of the plurality of first image regions is calculated (step S33); the first image region is divided into The second image is divided into a plurality of second image regions and calculates the second signal characteristics of each of the plurality of second image regions (step S34); compare the plurality of first signal characteristics with the plurality of second Signal characteristic (step S35); The second image regions are combined into a combined image (step S36).
如图1～3以及图4A～4B所示，接着说明本发明第一实施例的详细实施方式。在一实施例中，所述处理单元13控制所述光源15在所述图像传感器11获取图像F时点亮，以使所述图像传感器11所获取的图像F中包含来自所述待测物9的反射光图像I9，藉以计算所述待测物9的对象距离D。As shown in FIGS. 1 to 3 and FIGS. 4A to 4B , the detailed implementation of the first embodiment of the present invention will be described next. In one embodiment, the processing unit 13 controls the light source 15 to light up when the image sensor 11 acquires an image F, so that the image F acquired by the image sensor 11 includes The reflected light image I9 is used to calculate the object distance D of the object under test 9 .
步骤S31：所述图像传感器11受控于所述处理单元13的所述曝光控制单元131，以第一曝光时间ETL获取第一图像FL。Step S31: The image sensor 11 is controlled by the exposure control unit 131 of the processing unit 13 to acquire a first imageFL with a first exposure time ETL.
步骤S32：接着，所述图像传感器11受控于所述处理单元13(或所述曝光控制单元131)，以第二曝光时间ETH获取第二图像FH；其中，所述第一图像FL与所述第二图像FH可为所述图像传感器11所连续或者相隔至少一张图像所获取的两张图像F，且所述第一曝光时间ETL不同于所述第二曝光时间ETH；其中，所述相隔的至少一张图像例如为暗图像(即取像时所述光源15不点亮)，用于与所述第一图像FL及所述第二图像FH相减以消除环境光。必须说明的是，虽然图4A中显示所述第一曝光时间ETL小于所述第二曝光时间ETH，但本发明并不以此为限。在某些实施例中，所述第一曝光时间ETL大于所述第二曝光时间ETH。在一实施例中，所述处理单元13控制所述图像传感器11交替地以所述第一曝光时间ETL及所述第二曝光时间ETH进行图像获取。Step S32: Next, the image sensor 11 is controlled by the processing unit 13 (or the exposure control unit 131), and acquires a second image FH with a second exposure time ET H; wherein, the first image FL and the second image FH can be two images F acquired continuously by the image sensor 11 or separated by at least one image, and the first exposure time ETL is different from the second exposure time ETH ; wherein, the at least one image that is separated is, for example, a dark image (that is, the light source 15 is not turned on when taking an image), and is used to subtract the first imageFL and the second image FH to eliminate ambient light. It must be noted that, although it is shown in FIG. 4A that the first exposure time ETL isshorter than the second exposure timeETH , the present invention is not limited thereto. In some embodiments, the first exposure timeETL is greater than the second exposure timeETH . In one embodiment, the processing unit 13 controls the image sensor 11 to acquire images alternately with the first exposure time ETL and the second exposure time ETH.
步骤S33：所述处理单元13接收所述第一图像FL后，所述复用模块133以预设方式将所述第一图像FL分割为多个第一图像区域，例如A1～A4(图4B)，并计算所述多个第一图像区域A1～A4中每一者的第一信号特征C1～C4(图4B)；其中，所述多个第一图像区域A1～A4中每一者可为所述第一图像FL的一个列像素区域、多个列像素区域、一个行像素区域、多个行像素区域或矩形像素区域，并不限于图4B所示。在一实施例中，所述多个信号特征C1～C4分别为所述多个第一图像区域A1～A4的信噪比(SNR)；例如，所述复用模块133根据所述多个第一图像区域A1～A4中每一者的动态阈值区分信号数据(signal data)及噪声数据(noise data)，并根据所述信号数据及所述噪声数据计算所述信噪比，例如计算所述多个第一图像区域A1～A4中每一者所有信号数据的能量值总合与所有噪声数据的能量值总合的比值(ratio)，以作为所述信噪比。在一实施例中，所述动态阈值例如选择为一个第一图像区域中的最大能量值与平均能量值总合的平均值，但本发明并不以此为限，因此所述多个第一图像区域A1～A4中每一者均可求得一阈值。由于所述多个第一图像区域A1～A4中每一者的阈值是根据所获取的当前图像数据所计算，因此彼此可能不同，故本发明说明中称之为动态阈值。Step S33: After the processing unit 13 receives the first imageFL , the multiplexing module 133 divides the first imageFL into a plurality of first image regions in a preset manner, such as A1-A4( FIG. 4B ), and calculate the first signal features C1-C4 (FIG. 4B) of each of the plurality of first image regions A1-A4; wherein, each of the plurality of first image regions A1-A4 It can be one column pixel area, multiple column pixel areas, one row pixel area, multiple row pixel areas or rectangular pixel area of the first imageFL , and is not limited to that shown in FIG. 4B. In an embodiment, the multiple signal features C1-C4 are signal-to-noise ratios (SNR) of the multiple first image regions A1-A4 respectively; for example, the multiplexing module 133 A dynamic threshold for each of the image areas A1-A4 distinguishes signal data and noise data, and calculates the signal-to-noise ratio based on the signal data and the noise data, such as calculating the A ratio (ratio) of the sum of energy values of all signal data and the sum of energy values of all noise data in each of the plurality of first image areas A1 - A4 is used as the signal-to-noise ratio. In one embodiment, the dynamic threshold is selected as the average value of the sum of the maximum energy value and the average energy value in a first image region, but the present invention is not limited thereto, so the plurality of first Each of the image areas A1-A4 can obtain a threshold. Since the thresholds of each of the plurality of first image areas A1 - A4 are calculated according to the acquired current image data, they may be different from each other, so they are called dynamic thresholds in the description of the present invention.
步骤S34：同理，所述处理单元13接收所述第二图像FH后，所述复用模块133以所述预设方式(与步骤S33相同)将所述第二图像FH分割为多个第二图像区域，例如A1'～A4'(图4B)，并计算所述多个第二图像区域A1'～A4'中每一者的第二信号特征C1'～C4'(图4B)；其中，所述多个第二图像区域A1'～A4'中每一者可为所述第二图像FH的一个列像素区域、多个列像素区域、一个行像素区域、多个行像素区域或矩形像素区域，并不限于图4B所示。同理，所述多个信号特征C1'～C4'可分别为所述多个第二图像区域A1'～A4'的信噪比(SNR)；例如，所述复用模块133根据所述多个第二图像区域A1'～A4'中每一者的动态阈值区分信号数据及噪声数据，并根据所述信号数据及所述噪声数据计算所述信噪比，例如计算所有信号数据的能量值总合与所有噪声数据的能量值总合的比值，以作为所述信噪比。所述动态阈值的决定方式如步骤S33所述，故于此不再赘述。Step S34: Similarly, after the processing unit 13 receives the second image FH , the multiplexing module 133 divides the second image FH into multiple parts in the preset manner (same as step S33). A second image area, such as A1'～A4' (Figure 4B), and calculate the second signal features C1'～C4' (Figure 4B) of each of the plurality of second image areas A1'～A4'; Wherein, each of the plurality of second image areas A1'-A4' can be a column pixel area, a plurality of column pixel areas, a row pixel area, or a plurality of row pixel areas of the second image FH or a rectangular pixel area, and is not limited to that shown in FIG. 4B. Similarly, the multiple signal features C1'-C4' may be the signal-to-noise ratios (SNRs) of the multiple second image areas A1'-A4'respectively; for example, the multiplexing module 133 The dynamic threshold of each of the two second image areas A1'～A4' distinguishes signal data and noise data, and calculates the signal-to-noise ratio based on the signal data and the noise data, for example, calculates the energy value of all signal data The ratio of the sum to the sum of energy values of all noise data is used as the signal-to-noise ratio. The manner of determining the dynamic threshold is as described in step S33, so it will not be repeated here.
步骤S35：接着，所述复用模块133比较相对应的所述多个第一图像区域A1～A4与所述多个第二图像区域A1'～A4'的信号特征，例如比较所述第一图像区域A1的第一信号特征C1与所述第二图像区域A1'的第二信号特征C1'；比较所述第一图像区域A2的第一信号特征C2与所述第二图像区域A2'的第二信号特征C2'；比较所述第一图像区域A3的第一信号特征C3与所述第二图像区域A3'的第二信号特征C3'；以及比较所述第一图像区域A4的第一信号特征C4与所述第二图像区域A4'的第二信号特征C4'。Step S35: Next, the multiplexing module 133 compares the signal characteristics of the corresponding plurality of first image areas A1-A4 and the plurality of second image areas A1'-A4', for example, comparing the first The first signal characteristic C1 of the image area A1 and the second signal characteristic C1' of the second image area A1'; comparing the first signal characteristic C2 of the first image area A2 with the second signal characteristic C2 of the second image area A2' second signal characteristic C2'; comparing the first signal characteristic C3 of the first image area A3 with the second signal characteristic C3' of the second image area A3'; and comparing the first signal characteristic C3' of the first image area A4 The signal characteristic C4 is related to the second signal characteristic C4' of the second image area A4'.
步骤S36：接着，所述复用模块133利用时间复用机制(time multiplexingmechanism)将所述第一图像FL(此处显示为先获取图像)的部分图像区域与所述第二图像FH(此处显示为后获取图像)的部分图像区域进行重组以产生组合图像以作为所述待计算图像Fm。在一实施例中，所述复用模块133将信号特征较大的所述多个第一图像区域与信号特征较大的所述多个第二图像区域结合为组合图像。例如，假设所述多个第一信号特征C1及C4分别大于所述多个第二信号特征C1'及C4'，表示所述多个第一图像区域A1及A4相较于所述多个第二图像区域A1'及A4'较适用于计算正确的对象距离；并假设所述多个第一信号特征C2及C3分别小于所述多个第二信号特征C2'及C3'，表示所述多个第二图像区域A2'及A3'相较于所述多个第一图像区域A2及A3较适用于计算正确的对象距离。所述复用模块133则重组组合图像(即所述待计算图像Fm)，其包含图像区域A1、A2'、A3'及A4，如图4B所示。Step S36: Next, the multiplexing module 133 uses a time multiplexing mechanism (time multiplexing mechanism) to combine the partial image area of the first imageFL (here shown as the first acquired image) with the second image FH ( Part of the image area shown here as a post-acquisition image) is recombined to generate a combined image as the image to be calculated Fm. In an embodiment, the multiplexing module 133 combines the plurality of first image regions with larger signal characteristics and the plurality of second image regions with larger signal characteristics into a combined image. For example, assuming that the plurality of first signal features C1 and C4 are respectively greater than the plurality of second signal features C1' and C4', it means that the plurality of first image areas A1 and A4 are larger than the plurality of first image areas A1 and A4 The two image areas A1' and A4' are more suitable for calculating the correct object distance; and assuming that the plurality of first signal features C2 and C3 are respectively smaller than the plurality of second signal features C2' and C3', it means that the plurality of The second image areas A2' and A3' are more suitable for calculating the correct object distance than the plurality of first image areas A2 and A3. The multiplexing module 133 reassembles the combined image (ie, the image to be calculated Fm), which includes image areas A1 , A2 ′, A3 ′ and A4 , as shown in FIG. 4B .
可以理解的是，虽然图4B显示组合图像Fm分别包含了所述第一图像FL的部分图像区域(例如A1、A4)并包含了所述第二图像FH的部分图像区域(例如A2'、A3')，但本发明并不以此为限。根据所述图像传感器11实际获取的图像F，所述组合图像Fm可能与所述第一图像FL或所述第二图像FH相同。此外必须说明的是，图3中步骤S32并不限定为早于步骤S33，步骤S32可位于步骤S33之后而位于步骤S34之前。It can be understood that although FIG. 4B shows that the combined image Fm respectively includes partial image areas (for example, A1, A4) of the first imageFL andincludes partial image areas (for example, A2') of the second image FH , A3'), but the present invention is not limited thereto. According to the imageF actually captured by the image sensor 11, the combined image Fm may be the same as the first imageFL or the second image FH. In addition, it must be noted that step S32 in FIG. 3 is not limited to be earlier than step S33, and step S32 may be located after step S33 but before step S34.
最后，所述处理单元13的距离计算单元135则根据所述组合图像Fm计算至少一个对象距离D。必须说明的是，本实施例中的至少一个对象距离的个数例如可根据组合图像Fm的像素列的数目决定，例如每一像素列均求得相对应的对象距离或每多个像素列(例如2～5列)均求得相对应的对象距离，视其判断分辨率而定。所述距离计算单元135并可根据所求出的多个对象距离判断待测物个数并将关于相同待测物的对象距离合并为同一对象距离，因此所述距离计算单元135最后仅输出与待测物数目相对应数目的对象距离D。Finally, the distance calculation unit 135 of the processing unit 13 calculates at least one object distance D according to the combined image Fm. It should be noted that the number of at least one object distance in this embodiment can be determined according to the number of pixel columns of the combined image Fm, for example, the corresponding object distance can be obtained for each pixel column or every multiple pixel columns ( For example, 2 to 5 columns) can obtain the corresponding object distance, depending on the judgment resolution. The distance calculation unit 135 can judge the number of objects to be tested according to the obtained multiple object distances and combine the object distances about the same object to be measured into the same object distance, so the distance calculation unit 135 only outputs the same object distance at last. The number of objects to be tested corresponds to the number of object distances D.
此外，虽然图4A及图4B中显示所述处理单元13是比较两张图像FL及FH的不同图像区域的信号特征并产生组合图像Fm，但本发明并不以此为限。某些实施例中，所述处理单元13可比较两张以上的图像F的不同图像区域的信号特征并产生组合图像，其实施方式只需于步骤S36中选择所述两张以上的图像中，相对应图像区域中信号特征最大者以产生组合图像Fm即可，其它步骤S31～S35则与上述第一实施例相类似，仅另需增加以不同的至少一曝光时间获取图像F即可，故于此不再赘述。换句话说，本实施例的复用模块133将所述图像传感器11所获取的每张图像F区分为相同的(例如相同位置及相同尺寸)图像区域，以使组合图像Fm与图像F具有相同尺寸。此外，所述组合图像Fm还可为所述图像F中的欲处理图像区域(window ofinterest)，其可仅包含所述图像F的一部分。In addition, although it is shown in FIG. 4A and FIG. 4B that the processing unit 13 compares the signal characteristics of different image regions of the two imagesFL andFH to generate the combined image Fm, the present invention is not limited thereto. In some embodiments, the processing unit 13 can compare the signal characteristics of different image regions of two or more images F and generate a combined image. The implementation method only needs to select the two or more images in step S36, Corresponding to the one with the largest signal feature in the image area, it is enough to generate the combined image Fm, and the other steps S31-S35 are similar to the above-mentioned first embodiment, only need to add at least one different exposure time to obtain the image F, so No more details here. In other words, the multiplexing module 133 of this embodiment divides each image F acquired by the image sensor 11 into the same (for example, the same position and the same size) image area, so that the combined image Fm and the image F have the same size. In addition, the combined image Fm may also be an image area to be processed (window of interest) in the image F, which may only include a part of the image F.
综而言之，在第一实施例中，所述处理单元13可根据不同部分图像区域的图像质量，将不同图像帧中的不同部分图像区域重新组合为组合图像，以根据所述组合图像计算至少一个对象距离D，其中，所述部分图像区域的形状与尺寸并无特定限制。例如，处理单元13可根据图像质量(例如信号特征)，将所述第一图像FL中的部分图像区域，例如A1～A4的一部分，与所述第二图像FH中的部分图像区域，例如A1'～A4'的一部分，重新组合为组合图像Fm。To sum up, in the first embodiment, the processing unit 13 can recombine different partial image regions in different image frames into a combined image according to the image quality of different partial image regions, so as to calculate At least one object is at a distance D, wherein the shape and size of the partial image area are not limited. For example, the processing unit 13 may combine a part of the image area in the first imageFL , such as a part of A1 to A4, with a part of the image area in the second image FH according to the image quality (such as signal characteristics), For example, a part of A1' to A4' is recombined into a combined image Fm.
此外，为了进一步消除环境光的影响，所述处理单元13还可用于控制所述光源15以一操作频率相对所述图像传感器11的图像获取而点亮及熄灭，例如在所述光源15点亮时获取一张亮图像并在所述光源15熄灭时获取一张暗图像。所述处理单元13还可计算所述亮图像及所述暗图像的差分图像以作为上述第一实施例的所述第一图像FL及所述第二图像FH；也即，上述第一实施例中，所述第一图像FL可为第一差分图像而所述第二图像FH可为第二差分图像。In addition, in order to further eliminate the influence of ambient light, the processing unit 13 can also be used to control the light source 15 to be turned on and off with respect to the image acquisition of the image sensor 11 at an operating frequency, for example, when the light source 15 is turned on A bright image is acquired when the light source 15 is turned off and a dark image is acquired when the light source 15 is turned off. The processing unit 13 can also calculate the difference image of the bright image and the dark image as the first imageFL and the second image FH of the first embodiment; that is, the first In an embodiment, the first imageFL may be a first differential image and the second image FH may be a second differential image.
在某些实施例中，由于环境亮度变化与对象反射系数差异皆会导致侦测的动态范围改变，为了能让本发明说明的光学测距系统1实现更广的动态范围侦测，可进一步分别改变所述第一曝光时间ETL及所述第二曝光时间ETH。In some embodiments, since changes in ambient brightness and differences in object reflectance will result in changes in the dynamic range of detection, in order to enable the optical distance measuring system 1 described in the present invention to achieve wider dynamic range detection, it can be further divided The first exposure timeETL and the second exposure timeETH are changed.
如图5所示，其为本发明说明第二实施例的光学测距系统的操作示意图。在第二实施例中，所述光学测距系统同样包含所述图像传感器11、所述处理单元13以及所述光源15，如图1～2。本实施例与上述第一实施例的差异在于，上述第一实施例中，所述第一曝光时间ETL与所述第二曝光时间ETH为固定；而第二实施例中，所述第一曝光时间(例如显示为L1～L5)与所述第二曝光时间(例如显示为H1～H5)可调，或者所述第一曝光时间为固定而所述第二曝光时间可调；其中，所述第二曝光时间仍显示为大于所述第一曝光时间。As shown in FIG. 5 , it is a schematic diagram illustrating the operation of the optical distance measuring system according to the second embodiment of the present invention. In the second embodiment, the optical ranging system also includes the image sensor 11 , the processing unit 13 and the light source 15 , as shown in FIGS. 1-2 . The difference between this embodiment and the above-mentioned first embodiment is that, in the above-mentioned first embodiment, the first exposure time ETL and the second exposure time ETH are fixed; while in the second embodiment, the first An exposure time (for example, displayed as L1-L5) and the second exposure time (for example, displayed as H1-H5) are adjustable, or the first exposure time is fixed and the second exposure time is adjustable; wherein, The second exposure time is still shown to be greater than the first exposure time.
本实施例中，以差分图像来进行说明。如前所述，本实施例的差分图像也可适用于上述第一实施例的第一图像FL及第二图像FH。In this embodiment, a difference image is used for description. As mentioned above, the differential image in this embodiment can also be applied to the first imageFL and the second image FH in the above-mentioned first embodiment.
如图5所示，所述光源15以一操作频率发光。所述图像传感器11以第一曝光时间(例如显示为L1～L5)在所述光源15点亮(on)时获取第一亮图像Fb1及在所述光源15熄灭(off)时获取第一暗图像Fd1并以第二曝光时间(例如显示为H1～H5)相对所述光源15点亮时获取第二亮图像Fb2及相对所述光源15熄灭时获取第二暗图像Fd2。与上述第一实施例类似，所述处理单元13用于接收所述第一亮图像Fb1、所述第一暗图像Fd1、所述第二亮图像Fb2及所述第二暗图像Fd2，以计算所述第一亮图像Fb1与所述第一暗图像Fd1的第一差分图像、计算所述第二亮图像Fb2与所述第二暗图像Fd2的第二差分图像、将所述第一差分图像分割为多个第一图像区域(如图4B A1～A4)、将所述第二差分图像分割为多个第二图像区域(如图4B A1'～A4')、比较相对应的所述多个第一图像区域与所述多个第二图像区域的信号特征；以及将所述信号特征较大的所述多个第一图像区域与所述信号特征较大的所述多个第二图像区域组合为组合图像。本实施例中，除了计算所述第一差分图像及所述第二差分图像外，其它部分均与上述第一实施例相类似，故于此不再赘述。在一实施例中，所述差分图像将亮图像与暗图像进行像素对像素(pixel-by-pixel)的减法而得。As shown in FIG. 5 , the light source 15 emits light at an operating frequency. The image sensor 11 acquires the first bright image F b1 when the light source 15 is turned on (on) and acquires the first bright image Fb1 when the light source 15 is turned off (off) with a first exposure time (for example, shown as L1-L5). The dark image Fd1 and the second bright image Fb2 are obtained when the light source 15 is turned on with a second exposure time (for example, shown as H1 to H5 ), and the second dark image Fd2 is obtained when the light source 15 is turned off. Similar to the first embodiment above, the processing unit 13 is configured to receive the first bright image Fb1 , the first dark image Fd1 , the second bright image Fb2 and the second dark image Fd2 , to calculate the first differential image of the first bright image Fb1 and the first dark image Fd1 , and calculate the second differential image of the second bright image Fb2 and the second dark image Fd2 1. Divide the first difference image into multiple first image regions (as shown in Figure 4B A1-A4), and divide the second difference image into multiple second image regions (as shown in Figure 4B A1'～A4') , comparing the corresponding signal characteristics of the plurality of first image regions and the plurality of second image regions; and comparing the plurality of first image regions with larger signal characteristics with the larger signal characteristics The plurality of second image regions are combined into a combined image. In this embodiment, except for calculating the first differential image and the second differential image, other parts are similar to the above-mentioned first embodiment, so details will not be repeated here. In one embodiment, the difference image is obtained by subtracting the bright image and the dark image pixel-by-pixel.
在第二实施例中，可利用两种实施方式调整曝光时间。In the second embodiment, the exposure time can be adjusted using two implementations.
在一种实施方式中，所述处理单元13例如计算所述第一暗图像Fd1的第一平均亮度及所述第二暗图像Fd2的第二平均亮度。如前所述，第二实施例的目的是通过调整曝光时间来消除环境光的影响，因此利用暗图像(即光源熄灭时所获取者)的平均亮度评价环境光。所述处理单元13根据所述第一暗图像Fd1的第一平均亮度(例如图5的BL1～BL4)调整所述第一曝光时间(例如图5的L1～L5)并根据所述第二暗图像Fd2的第二平均亮度(例如图5的BH1～BH4)调整所述第二曝光时间(例如图5的H1～H5)。In one implementation manner, the processing unit 13 calculates, for example, a first average brightness of the first dark image Fd1 and a second average brightness of the second dark image Fd2 . As mentioned above, the purpose of the second embodiment is to eliminate the influence of ambient light by adjusting the exposure time, so the average brightness of the dark image (that is, the one acquired when the light source is turned off) is used to evaluate the ambient light. The processing unit 13 adjusts the first exposure time (such as L1 to L5 in FIG. 5 ) according to the first average brightness of the first dark image Fd1 (such as BL1 to BL4 in FIG. The second average brightness of the second dark image Fd2 (eg, BH1 -BH4 in FIG. 5 ) adjusts the second exposure time (eg, H1 - H5 in FIG. 5 ).
例如图5中，所述处理单元13根据所述第一暗图像Fd1的第一平均亮度BL1将第一曝光时间L1调整为L2，根据所述第一暗图像Fd1的第一平均亮度BL2将第一曝光时间L2调整为L3，依此类推；所述处理单元13根据所述第二暗图像Fd2的第二平均亮度BH1将第二曝光时间H1调整为H2，根据所述第二暗图像Fd2的第二平均亮度BH2将第二曝光时间H2调整为H3，依此类推。必须说明的是，虽然图5中显示第一曝光时间与第二曝光时间每次均被调整，然其仅用以说明，并非用以限定本发明，依实际所获取的图像F，第一曝光时间与第二曝光时间可能不被调整。For example, in FIG. 5, the processing unit 13 adjusts the first exposure time L1 to L2 according to the first average brightness BL1 of the first dark image Fd1 , and adjusts the first exposure time L1 to L2 according to the first average brightness B L1 of the first dark image Fd1 . BL2 adjusts the first exposure time L2 to L3, and so on; the processing unit 13 adjusts the second exposure time H1 to H2 according to the second average brightness BH1 of the second dark image Fd2 , according to the The second average brightness BH2 of the second dark image Fd2 adjusts the second exposure time H2 to H3, and so on. It must be noted that although the first exposure time and the second exposure time are adjusted each time shown in FIG. 5 , it is only used for illustration, not to limit the present invention. According to the actually acquired image F, the first exposure time Time and second exposure times may not be adjusted.
参考图6所示，其为本发明说明第二实施例的光学测距系统中阈值设定的示意图。所述处理单元11用于将所述第一平均亮度(例如BL1～BL4)与第一上阈值及第一下阈值比较以调整所述第一曝光时间(例如L1～L5)；其中，当所述第一平均亮度大于所述第一上阈值时调短获取下一张图像时的所述第一曝光时间，当所述第一平均亮度小于所述第一下阈值时调长获取下一张图像时的所述第一曝光时间，否则维持所述第一曝光时间。所述处理单元11用于将所述第二平均亮度(例如BH1～BH4)与第二上阈值及第二下阈值比较以调整所述第二曝光时间(例如H1～H5)；其中，当所述第二平均亮度大于所述第二上阈值时调短获取下一张图像时的所述第二曝光时间，当所述第二平均亮度小于所述第二下阈值时调长获取下一张图像时的所述第二曝光时间，否则维持所述第二曝光时间。在一实施例中，所述第一上阈值可设定为大于所述第二下阈值，以避免暗图像的平均亮度位于阈值附近时的振荡。Referring to FIG. 6 , it is a schematic diagram illustrating the threshold setting in the optical ranging system of the second embodiment of the present invention. The processing unit 11 is configured to compare the first average brightness (eg, BL1-BL4 ) with a first upper threshold and a first lower threshold to adjust the first exposure time (eg, L1 -L5); wherein, When the first average brightness is greater than the first upper threshold, shorten the first exposure time for acquiring the next image; The first exposure time for one image, otherwise maintain the first exposure time. The processing unit 11 is configured to compare the second average brightness (eg BH1 -BH4 ) with a second upper threshold and a second lower threshold to adjust the second exposure time (eg H1 - H5 ); wherein, When the second average brightness is greater than the second upper threshold, shorten the second exposure time for acquiring the next image; The second exposure time for one image, otherwise maintain the second exposure time. In an embodiment, the first upper threshold may be set to be greater than the second lower threshold, so as to avoid oscillation when the average brightness of the dark image is near the threshold.
在另一实施方式中，所述处理单元13根据所述第二暗图像Fd2中对象图像尺寸调整所述第二曝光时间(例如H1～H5)。In another embodiment, the processing unit 13 adjusts the second exposure time (for example, H1 to H5 ) according to the object image size in the second dark image Fd2 .
例如参考图7所示，所述处理单元13根据所述第二暗图像Fd2的对象图像尺寸IS1将所述第二曝光时间H1调整为H2，根据所述第二暗图像Fd2的对象图像尺寸IS2将所述第二曝光时间H2调整为H3，依此类推。本实施例中，所述第一曝光时间(例如L1～L5)维持固定。同理，虽然图7中显示第二曝光时间每次均被调整，然其仅用以说明，并非用以限定本发明，依实际所获取的图像F，第二曝光时间可能不被调整。For example, as shown in FIG. 7, the processing unit 13 adjusts the second exposure time H1 to H2 according to the object image size IS1 of the second dark image Fd2 , and adjusts the second exposure time H1 to H2 according to the object image size IS1 of the second dark image Fd2 . Image size IS2 adjusts said second exposure time H2 to H3 and so on. In this embodiment, the first exposure time (for example, L1 - L5 ) remains constant. Similarly, although it is shown in FIG. 7 that the second exposure time is adjusted each time, it is only for illustration and not for limiting the present invention. According to the actual acquired image F, the second exposure time may not be adjusted.
如图8所示，其为本发明第二实施例的光学测距系统中决定对象图像尺寸的示意图。本实施方式中，所述对象图像尺寸可为二维尺寸，也即对象图像的像素数目；或者，所述对象图像尺寸可为一维尺寸，也即对象图像的宽度W1和/或高度W2。图8中，可将像素序列中，灰度值大于灰度阈值I_TH的像素设为”1”，而将灰度值小于所述灰度阈值I_TH的像素设为”0”，藉以计算对象图像的有效宽度W1_eff和/或有效高度W2_eff，以作为所述对象图像尺寸。此外，为节省资源，可不处理整张暗图像F的数据而仅处理欲处理图像区域WOI范围内的像素数据，并忽略所述欲处理图像区域WOI以外的像素数据；其中，所述欲处理图像区域WOI的范围可根据实际量测时对象图像可能出现的位置而定。As shown in FIG. 8 , it is a schematic diagram of determining the image size of an object in the optical ranging system according to the second embodiment of the present invention. In this embodiment, the size of the object image may be two-dimensional, that is, the number of pixels of the object image; or, the size of the object image may be one-dimensional, that is, the width W1 and/or the height W2 of the object image. In Figure 8, in the pixel sequence, the pixels whose grayscale value is greater than the grayscale threshold I_TH can be set to "1", and the pixels whose grayscale value is smaller than the grayscale threshold I_TH can be set to "0", so as to calculate the target image The effective width W1_eff and/or the effective height W2_eff is used as the target image size. In addition, in order to save resources, the data of the entire dark image F may not be processed, but only the pixel data within the WOI of the image area to be processed can be processed, and the pixel data outside the WOI of the image area to be processed can be ignored; wherein, the image to be processed The scope of the region WOI may be determined according to the possible positions of the object image during actual measurement.
本实施方式中，所述处理单元13可当所述对象图像尺寸大于上阈值时，调短所述第二曝光时间(例如H1～H5)；而当所述对象图像尺寸小于下阈值时，调长所述第二曝光时间(例如H1～H5)。In this embodiment, the processing unit 13 may shorten the second exposure time (such as H1-H5) when the size of the object image is greater than the upper threshold; Longer the second exposure time (for example H1-H5).
参考图9A及9B所示，其为本发明说明第三实施例的光学测距系统的操作示意图。相对于公知技术，上述第一实施例及第二实施例利用长短不同曝光时间获取的两张图像F重新组合一张待计算图像Fm，所以具有较高的帧率(frame rate)。因此，第三实施例是用于节省系统耗能及资源，并可应用于上述第一实施例及第二实施例中。Referring to FIGS. 9A and 9B , they are schematic diagrams illustrating the operation of the optical distance measuring system according to the third embodiment of the present invention. Compared with the known technology, the above-mentioned first embodiment and the second embodiment use two images F obtained with different exposure times to recombine an image Fm to be calculated, so they have a higher frame rate. Therefore, the third embodiment is used to save system power consumption and resources, and can be applied to the above-mentioned first and second embodiments.
本实施例中，所述光学测距系统同样包含所述图像传感器11、所述处理单元13以及所述光源15，如图1～2。In this embodiment, the optical ranging system also includes the image sensor 11 , the processing unit 13 and the light source 15 , as shown in FIGS. 1-2 .
所述图像传感器11可以一参考曝光时间ETr获取参考暗图像Frd(即光源熄灭时所获取)、以第一曝光时间ETL获取第一图像FL并以第二曝光时间ETH获取一第二图像FH；其中，所述参考暗图像Frd用于判定是否开始进入上述第一实施例或第二实施例的操作模式。如前所述，所述第一图像FL及所述第二图像FH可为差分图像，以消除环境光的影响。在一实施例中，所述参考曝光时间ETr可与所述第二曝光时间ETH相同，如图9A所示。在另一实施例中，所述参考曝光时间ETr可与所述第二曝光时间H1～H5不相同，如图9B所示。The image sensor 11 can acquire a reference dark image Frd (acquired when the light source is turned off) with a reference exposure time ETr, acquire a first image FL with a first exposure time ETL and acquire a second imageFL with a second exposure time ETH Image FH ; wherein, the reference dark image Frd is used to determine whether to enter the operation mode of the first embodiment or the second embodiment above. As mentioned above, the first imageFL and the second image FH can be differential images to eliminate the influence of ambient light. In an embodiment, the reference exposure timeETr may be the same as the second exposure time ETH, as shown in FIG. 9A . In another embodiment, the reference exposure time ETr may be different from the second exposure times H1 - H5 , as shown in FIG. 9B .
所述处理单元13则用于当判断所述参考暗图像Frd中存在对象图像时，控制所述图像传感器11交替地以所述第一曝光时间ETL获取所述第一图像FL并以所述第二曝光时间ETH获取所述第二图像FH；而当判断所述参考暗图像Frd中不存在任何对象图像时，控制所述图像传感器11以所述参考曝光时间ETr获取另一参考暗图像Frd以重新进行判断。更具体地，当所述处理单元13判断根据所述参考曝光时间ETr(例如第二曝光时间ETH)获取的所述参考暗图像Frd中存在对象时，才开始进入上述第一实施例或第二实施例之光学测距方法；否则，所述光学测距系统1进入一闲置模式；其中，判断图像中是否存在对象的方式已为公知，例如判断是否有预设数目的像素灰度值大于预设阈值，故于此不再赘述。The processing unit 13 is configured to control the image sensor 11 to alternately acquire the first imageFL with the first exposure time ETL and to obtain the first image FL with the determined reference dark image Frd when it is determined that there is an object image in the reference dark image Frd. The second exposure time ETH is used to obtain the second image FH ; and when it is judged that there is no object image in the reference dark image Frd, the image sensor 11 is controlled to obtain another reference image with the reference exposure time ETr Darken the image Frd to redo the judgment. More specifically, when the processing unit 13 judges that there is an object in the reference dark imageFrd acquired according to the reference exposure time ETr (for example, the second exposure time ETH), it starts to enter the above-mentioned first embodiment or the second embodiment. The optical distance measuring method of the second embodiment; otherwise, the optical distance measuring system 1 enters an idle mode; wherein, the method of judging whether there is an object in the image is known, such as judging whether there is a preset number of pixels whose gray value is greater than The threshold is preset, so it will not be repeated here.
此外，此处所谓闲置模式可为熄灭光源、在所述第一曝光时间(例如短曝光时间)停止获取图像、不根据两张图像F重组一张待计算图像Fm、不计算对象距离等至少其中的一者，藉以降低系统耗能及资源。In addition, the so-called idle mode here can be to turn off the light source, stop acquiring images at the first exposure time (for example, short exposure time), not reconstruct an image Fm to be calculated according to the two images F, not calculate the object distance, etc. at least among them One of them, so as to reduce system energy consumption and resources.
如图9A所示，当第三实施例应用于第一实施例时且当离开闲置模式而进入操作模式(即如图4A所示)后，若所述处理单元13根据所述第二暗图像(即以所述第二曝光时间ETH相对所述光源15熄灭时所获取的图像)判断不存在对象图像(例如对象离开所述图像传感器11的视野范围)，所述光学测距系统1再进入所述闲置模式。As shown in FIG. 9A , when the third embodiment is applied to the first embodiment and after leaving the idle mode and entering the operation mode (as shown in FIG. 4A ), if the processing unit 13 according to the second dark image (that is, the image obtained when the light source 15 is turned off with the second exposure time ETH ) determines that there is no object image (for example, the object leaves the field of view of the image sensor 11), and the optical distance measuring system 1 again Enter the idle mode.
如图9B所示，当第三实施例应用于第二实施例时且当离开闲置模式而进入操作模式(即如图5所示)后，若所述处理单元13根据所述第二暗图像(例如Fd2)判断不存在对象图像(例如对象离开所述图像传感器11的视野范围)，所述光学测距系统1再进入闲置模式。As shown in FIG. 9B , when the third embodiment is applied to the second embodiment and after leaving the idle mode and entering the operation mode (as shown in FIG. 5 ), if the processing unit 13 according to the second dark image (for example, Fd2 ) it is judged that there is no object image (for example, the object leaves the field of view of the image sensor 11 ), and the optical distance measuring system 1 enters the idle mode again.
上述各实施例中，所述处理单元13的复用模块133用于分割多个图像F并计算不同图像区域(如图4B所示)的信号特征，例如信噪比或平均亮度，以输出待计算图像Fm供所述距离计算单元135计算至少一个对象距离D。第一实施例中，所述曝光控制单元131以预设的曝光时间控制所述图像传感器11获取不同图像(例如FL及FH)，且所述曝光控制单元131控制所述图像传感器11获取不同图像的曝光时间为预设的固定值(例如图4A的ETL、ETH)。第二实施例中，所述曝光控制单元131控制所述图像传感器11获取不同图像(例如Fb1、Fd1、Fb2、Fd2)的短曝光时间(例如L1～L5)及长曝光时间(例如H1～H5)为可变值，以进一步增加可侦测动态范围。第三实施例中，当一参考曝光时间ETr所获取的参考暗图像Frd未包含对象图像时，所述光学测距系统1则操作于闲置模式，或者在操作模式时未侦测到以长曝光时间(例如第二曝光时间ETH或H1～H5)所获取的暗图像包含对象图像时，所述光学测距系统1则再度进入所述闲置模式，以节省系统耗能及资源。In each of the above embodiments, the multiplexing module 133 of the processing unit 13 is used to divide a plurality of images F and calculate signal characteristics of different image regions (as shown in FIG. 4B ), such as signal-to-noise ratio or average brightness, to output The calculated image Fm is used for the distance calculation unit 135 to calculate at least one object distance D. In the first embodiment, the exposure control unit 131 controls the image sensor 11 to acquire different images (such asFL and FH ) with a preset exposure time, and the exposure control unit 131 controls the image sensor 11 to acquire The exposure time of different images is a preset fixed value (such as ETL andETH in FIG.4A ). In the second embodiment, the exposure control unit 131controls the short exposure time (such asL1 -L5 ) and the longexposure time ( For example, H1-H5) are variable values to further increase the detectable dynamic range. In the third embodiment, when the reference dark image Frd acquired by a reference exposure time ETr does not contain the object image, the optical distance measuring system 1 operates in the idle mode, or does not detect the long exposure in the operating mode When the dark image acquired at a certain time (such as the second exposure time ETH or H1˜H5) contains an object image, the optical ranging system 1 enters the idle mode again to save system energy consumption and resources.
综上所述，现有的光学测距系统存在无法精确测量不同位置的多个待测物距离的问题，尤其在测量远距离待测物时可能出现无法测量的情形。因此，本发明提供一种光学测距系统(图1、2)及光学测距方法(图4A～4B、5、7、9A～9B)，其通过时间复用曝光机制以同时保留不同距离的待测物的图像数据，藉以增加计算精确度。To sum up, the existing optical distance measuring system has the problem of being unable to accurately measure the distances of multiple objects under test at different locations, especially when measuring distant objects under test. Therefore, the present invention provides an optical ranging system (Fig. 1, 2) and an optical ranging method (Fig. The image data of the object under test is used to increase the calculation accuracy.
虽然本发明已通过上述实例公开，但是其并非用于限定本发明，任何本发明所属技术领域的技术人员，在不脱离本发明的精神和范围内，当可作各种的更动与修改。因此本发明的保护范围当以所附权利要求书所限定范围为准。Although the present invention has been disclosed through the above examples, they are not intended to limit the present invention. Any person skilled in the art to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope defined by the appended claims.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811433990.2ACN109905610B (en) | 2015-01-23 | 2015-01-23 | Exposure time adjustment method of optical ranging system |
| CN201510033318.4ACN105872392B (en) | 2015-01-23 | 2015-01-23 | Optical ranging system with dynamic exposure time |
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| CN201510033318.4ACN105872392B (en) | 2015-01-23 | 2015-01-23 | Optical ranging system with dynamic exposure time |
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| CN201811433990.2ADivisionCN109905610B (en) | 2015-01-23 | 2015-01-23 | Exposure time adjustment method of optical ranging system |
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| CN105872392Atrue CN105872392A (en) | 2016-08-17 |
| CN105872392B CN105872392B (en) | 2019-01-04 |
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| CN201510033318.4AActiveCN105872392B (en) | 2015-01-23 | 2015-01-23 | Optical ranging system with dynamic exposure time |
| CN201811433990.2AActiveCN109905610B (en) | 2015-01-23 | 2015-01-23 | Exposure time adjustment method of optical ranging system |
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| CN201811433990.2AActiveCN109905610B (en) | 2015-01-23 | 2015-01-23 | Exposure time adjustment method of optical ranging system |
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