Abstract:
A method for configuring parameter values for a plurality of cameras ( 100   a - 100   f ) is disclosed. In the first step of the method, image data from the plurality of cameras ( 100   a - 100   f ) is acquired. Secondly, the image data from the plurality of cameras ( 100   a - 100   f ) is buffered. Thirdly, the buffered image data from the plurality of cameras ( 100   a - 100   f ) is displayed. Fourthly, at least one parameter value for a first subset of said plurality of cameras is changed. Fifthly, the at least one parameter value is transmitted to said first subset of cameras. Sixthly, the changed image data from a second subset of said plurality of cameras is acquired. Seventhly, the buffered image data for said second subset of cameras is replaced with said changed image data for said second subset of cameras. Finally, the stored image data for said plurality of cameras ( 100   a - 100   f ) is displayed.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is claims the benefit of provisional application No. 60/830,963 filed on Jul. 14, 2006, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention generally relates to a method for configuring parameter values for a plurality of cameras, an apparatus comprising a processing device, a display adapted for showing image data, an input device, a memory adapted for holding a number of parameter values and for buffering image data, and a data communication interface adapted for communication through a data communications network with a plurality of cameras, a method for parameter value configuration of a camera, a camera having a processor device, a memory adapted for holding a number of parameter values, and a data communication interface adapted for communication through a data communications network, said camera stores parameter values which control the appearance of image data captured by said camera, a system for configuration of at least one parameter value in a plurality of cameras, comprising a camera and an apparatus, and a computer program. 
       BACKGROUND 
       [0003]    A modern security system often comprises a number of surveillance cameras. The surveillance cameras give the security personnel a possibility to monitor a large area, such as several floors in an office building. 
         [0004]    When having a number of cameras, the appearance of the images from the number of cameras should preferably be substantially similar with respect to brightness, sharpness, etc., since this makes the work of the operator less tiresome. More particularly, for a human eye, it is less tiresome analysing a number of images having similar appearance, than analysing a number of images with dissimilar appearance. 
         [0005]    When having a number of cameras, the cameras are most often placed at different places having different light conditions, which makes predetermined settings a non-optimal alternative. Further, the number of cameras may be different types of cameras with, for example, different types of image sensors, which even further make predetermined settings a non-optimal alternative. 
         [0006]    US 2003/0234866A1 describes a practical real-time calibration of digital omnidirectional cameras in the areas of de-vignetting, brightness, contrast and white balance control. Novel solutions for the colour calibration of an omnidirectional camera rig, and an efficient method for devignetting images are also presented. Additionally, a context-specific method of stitching images together into a panorama or a mosaic is provided. 
       SUMMARY 
       [0007]    In view of the above, an objective of the invention is to solve or at least reduce the problems discussed above. In particular, an objective is to provide a method for configuring parameter values for a plurality of cameras, wherein an image feedback is provided after a reconfiguration of the parameter values. 
         [0008]    The plurality of cameras may be all the cameras connected to a certain data communications network, but may also be a subset of cameras connected to the data communications network. 
         [0009]    Image data generated by the cameras may be analog or digital, but preferably digital. Further, the image data may be still pictures, as well as video sequences. In one embodiment, the plurality of cameras generate video sequences normally, but still pictures as image feedback. 
         [0010]    A first aspect of the invention is a method for configuring parameter values for a plurality of cameras, comprising acquiring image data from said plurality of cameras, said cameras store parameter values which control the appearance of image data captured by said cameras, buffering said image data from said plurality of cameras, displaying said buffered image data from said plurality of cameras, changing at least one parameter value for a first subset of said plurality of cameras, transmitting said at least one changed parameter value to said first subset of cameras to allow update of said at least one parameter value in each camera in said first subset, acquiring changed image data from a second subset of said plurality of cameras comprising at least the cameras of the first subset, replacing said buffered image data for said second subset of cameras with said changed image data for said second subset of cameras, and displaying said buffered image data for said plurality of cameras. 
         [0011]    An advantage with this first aspect is that an image feedback is given after changing the parameter values. In this way the user of an apparatus, configured to perform the steps according to the method of the first aspect, will easily see if the change of parameter values produced the desired result or not. 
         [0012]    The first subset of the method may be a part of the second subset. 
         [0013]    Alternatively, the first subset may be equal to the second subset. 
         [0014]    Alternatively, the second subset may be equal to the plurality of cameras. 
         [0015]    The changing may involve receiving a user input from a user, and changing said at least one parameter value in accordance with said user input. 
         [0016]    An advantage of this is that the user of the apparatus, performing the steps of the method according to the first aspect, may determine for himself in which way the parameter values is to be changed. 
         [0017]    Alternatively, the changing may involve determining reference image data, calculating a correction value based on said reference image data, and changing said at least one parameter value in accordance with said correction value. 
         [0018]    An advantage of this is that no user interaction is required, which implies that the configuration of the parameter values may be made quickly. 
         [0019]    The step of acquiring image data according to the first aspect of the invention may involve transmitting an image data request to said plurality of cameras. 
         [0020]    The method according to the first aspect may further involve retrieving at least one parameter value from a predetermined set of parameter values. 
         [0021]    An advantage of this is that a number of sets of predetermined parameter values for different environments may be provided to the user of the apparatus, performing the steps according to the method of the first aspect, wherein each such set of predetermined parameter values will function as a selectable template. In this way a first approximation of suitable parameter values may be easily and quickly done by the user of the apparatus by selecting the desired set of predetermined parameter values. 
         [0022]    The set of predetermined parameter values may be selected from a group consisting of, but not limited to: a set of predetermined parameter values adapted for outdoor conditions, a set of predetermined parameter values adapted for indoor conditions, a set of predetermined parameter values adapted for fluorescent lighting conditions, a set of predetermined parameter values adapted for incandescent light conditions and a set of predetermined parameter values adapted for infrared light conditions. 
         [0023]    The step of retrieving may further involve receiving a user input from a user, and retrieving said set of predetermined parameter values in accordance with said user input. 
         [0024]    The at least one parameter value may be selected from a group consisting of, but not limited to: a white balance value, a contrast value, a rotation value, a compression value, a sharpness value and a colour balance value. 
         [0025]    Further, the parameter values may be acquired together with said image data from said plurality of cameras in said acquiring of image data and are displayed in said displaying of image data together with said image data. 
         [0026]    Moreover, acquiring of said image data, buffering of said image data, displaying of said image data, changing of at least one parameter value for said first subset, transmitting of said at least one parameter value, acquiring of changed image data from said second subset, replacing of said buffered image data for said second subset, and displaying of said buffered image data, may be repeated iteratively until a user acceptance signal is received from a user. 
         [0027]    A second aspect of the invention is an apparatus comprising a processing device, a display adapted for showing image data, an input device, a memory adapted for holding a number of parameter values and for buffering image data, and a data communication interface adapted for communication through a data communications network with a plurality of cameras, wherein the processing device being adapted to acquire image data from said plurality of cameras, buffer said image data from said plurality of cameras in said memory, display said buffered image data from said plurality of cameras on said display, change at least one parameter value for a first subset of said plurality of cameras based upon an actuation of said input device, transmit said at least one parameter value to said first subset of cameras through said data communications network, to allow update of said at least one parameter value in each camera in said first subset, acquire changed image data from a second subset of said plurality of cameras through said data communications network, replace said buffered image data for said second subset of cameras with said changed image data for said second subset of cameras in said memory, and display said buffered image data for said plurality of cameras on said display. 
         [0028]    The apparatus according to the second aspect may comprise a personal computer (PC). 
         [0029]    An advantage of this is that any PC connected to a LAN (Local Area Network) to which a plurality of cameras is connected may be used as the apparatus according to the second aspect of the invention. 
         [0030]    The apparatus according to the second aspect may alternatively comprise a mobile terminal. 
         [0031]    The apparatus according to the second aspect of the invention may be adapted to perform the method according to the first aspect of the invention. 
         [0032]    A third aspect of the invention is a method for parameter value configuration of a camera coupled to an apparatus through a data communications network, said camera stores parameter values which control the appearance of image data captured by said camera, whereby the steps, in said camera, of receiving an image data request from said apparatus, generating image data, using said parameter values, upon receiving said image data request, transmitting said image data to said apparatus, receiving a parameter value change request from said apparatus, changing at least one parameter value among said parameter values held in said camera based upon said parameter value change request, generating, using said parameter values as changed, changed image data, and transmitting said changed image data to said apparatus through said data communications network. 
         [0033]    A fourth aspect of the invention is a camera having a processing device, a memory adapted for holding a number a parameter values, and a data communication interface adapted for communication through a data communications network, said camera stores parameter values which control the appearance of image data captured by said camera, whereby the processing device being adapted to receive an image data request from an apparatus through said data communications network, generate image data, using said parameter values, upon receiving said received image data request, transmit said image data to said apparatus through said data communications network, receive a parameter value change request from said apparatus through said data communications network, change at least one parameter value among said parameter values held in said memory in accordance with said parameter value change request, generate, using said parameter values as changed, changed image data, with said parameter values being changed, upon said parameter value change request, and transmit said changed image data to said apparatus through said data communications network. 
         [0034]    A fifth aspect of the invention is a system for configuration of at least one parameter value in a plurality of cameras, comprising a data communications network, an apparatus according to the fourth aspect, connected to said data communications network, and a plurality of cameras configured for communication with said apparatus through said data communications network. 
         [0035]    A sixth aspect of the invention is a computer program, comprising computer program code for performing the steps of the method according to the first aspect. 
         [0036]    The third to sixth aspects of the invention may have substantially the same or corresponding features, whenever applicable, as the first and second aspects. 
         [0037]    Other objectives, features and advantages of the present invention will appear from the following detailed disclosure, from the attached dependent claims as well as from the drawings. 
         [0038]    Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the [element, device, component, means, step, etc]” are to be interpreted openly as referring to at least one in-stance of said element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein: 
           [0040]      FIG. 1  illustrates a general surveillance camera system comprising a plurality of cameras, a data communications network and an apparatus. 
           [0041]      FIG. 2  illustrates one of the plurality of cameras in the general surveillance camera system in more detail. 
           [0042]      FIG. 3  illustrates the apparatus in the general surveillance camera system in more detail. 
           [0043]      FIG. 4  illustrates a graphical user interface of the apparatus. 
           [0044]      FIG. 5  illustrates a flow chart describing a general method for configuring a number of cameras. 
           [0045]      FIG. 6  illustrates a first embodiment of the present invention. 
           [0046]      FIG. 7  illustrates a second embodiment of the present invention. 
           [0047]      FIG. 8  illustrates a third embodiment of the present invention. 
           [0048]      FIG. 9  illustrates a fourth embodiment of the present invention. 
           [0049]      FIG. 10  illustrates a method for configuring parameter values. 
           [0050]      FIG. 11  illustrates a method for parameter configuration of a camera. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    A General Surveillance Camera System 
         [0052]      FIG. 1  illustrates a general surveillance camera system with a plurality of cameras  100   a - 100   f . Each camera is connected to a data communications network  102 , such as a TCP/IP-based Local Area Network (LAN) or a TCP/IP-based Wireless Local Area Network (WLAN). An apparatus  104  for receiving and presenting image data from the cameras  100   a - 100   f  is also connected to the data communications network. 
         [0053]    Although it is a great advantage to use an established standard such as the TCP/IP, this is not a must. Actually, any data communications network adapted to pass information, analog as well as digital, from cameras to an apparatus may be utilised for realising the present invention. 
         [0054]    Moreover, the apparatus  104  can also be utilised for configuring the parameter values for each camera  100   a - 100   f . This may, for instance, be to set the sharpness value for each of the camera to an appropriate value. 
         [0055]    In  FIG. 1 , only one apparatus is shown. It is only required one apparatus to realise the invention, however, there may be more than one apparatus present. 
         [0056]    The Camera 
         [0057]      FIG. 2  illustrates one of the cameras  100   a - 100   f  connected to the data communications network  102  shown in  FIG. 1  in more detail. 
         [0058]    The camera  100  comprises a lens  200 , an image sensor  202 , a processing device  204 , a memory  206 , a compression engine  208  and a data communication interface  210 . 
         [0059]    The lens  200  comprises optics adapted to focus incoming light onto the image sensor. Further, a number of associated devices for controlling the incoming light may be associated to the lens  200 , such as a shutter for adjusting the amount of light and an exposure time control device for controlling the exposure time of the camera. Hereinafter, when referring to the lens  200  the associated devices should be included as well. 
         [0060]    Generally, light is transferred via the lens  200  to the image sensor  202 . In the image sensor  202 , an image is captured by generating image data which is thereafter transferred to the processing device  204 . The processing device  204  can be one or several processors adapted to process the image data generated by the image sensor  202 . Such processing can be motion detection, adding a time stamp to the present image data, and changing the parameter values of the image sensor  202 . The processing device can, for instance, be an ETRAX 100LX 32-bit ASIC which is made commercially available by AXIS Communications AB. 
         [0061]    Further, the memory  206  is utilised by the processing device  204 , e.g. for storing parameter values. The memory can be divided into a RAM memory and a Flash memory. 
         [0062]    Thereafter, the image data is transferred to the compression engine  208 . In the compression engine the image data is compressed in accordance with a compression format, such as MPEG-4 or Motion-JPEG. 
         [0063]    Finally, the compressed image data is output to the data communications network  102  via the data communication interface  210 . The data communication interface can be Ethernet-compliant in the physical form of an RJ-45 connector. 
         [0064]    Additionally, the camera  100  is adapted to receive new parameter values via the data communications network  102  utilising the data network interface  210 . After having received new parameter values the present parameter values stored in the memory  206  can, by using the processing device  204 , be replaced by the received new parameter values. 
         [0065]    Moreover, the camera comprises some sort of power supply (not shown), such as a battery, or is connected to the mains via an electric cable or via an electric cable comprised within an Ethernet cable (known as Power over Ethernet (IEEE 802.3af)). 
         [0066]    The Apparatus 
         [0067]    The apparatus  104  connected to the data communications network  102  is further illustrated in  FIG. 3 . 
         [0068]    In  FIG. 3 , the apparatus  104  is illustrated as a PC generally comprising a display  300 , an input device  302 , illustrated as a keyboard, and a computing unit  304 , wherein the computing unit  304  further comprises a processing device  306 , a memory  308  and a data communication interface  310  communicating with the data communications network  102 . 
         [0069]    Data is received from and transmitted to the data communications network  102  via the data communications interface  310 , which can be similar to the data communication interface  210  of the camera  200 . 
         [0070]    The received data is transferred to the processing device  306 , in which the data is processed. This processing can comprise, if the received data is image data from the camera  300 , transferring the received image data to the display  300 . 
         [0071]    Data can also be received by the processing device  306  from the input device  302 . Such data can, for instance, be data describing changes, or new values, of the camera parameter values, input by the user of the input device  302  to be transferred through the data communications network  102  to the camera  100 . 
         [0072]    Although the apparatus  104  is illustrated as a PC, the apparatus can, in another embodiment, be a mobile terminal, a PDA or any other device having a display and processing capabilities. 
         [0073]    As an alternative to the wire-based keyboard illustrated in  FIG. 3 , the input device  302  can communicate wirelessly with the computing unit  304 . For instance, the input device  302  can be embodied as a remote control communicating with a computing unit  304  via IR light. 
         [0074]    In another embodiment, the input device  302  can be a mobile terminal communicating with the computing unit  304  via a mobile terminal communications network, such as a GSM network. In this embodiment, a mobile terminal network communications interface may have to be added to the computing unit  304 . 
         [0075]    An Alternative Approach 
         [0076]    An alternative approach, based on that the changes are made in the cameras  100   a - 100   f , is that the apparatus  104  can be divided into an input sub-apparatus and an output sub-apparatus. 
         [0077]    The input sub-apparatus can be a mobile terminal, which communicates directly with the cameras  100   a - 100   f  via a mobile terminal communications network, such as a GSM network, which implies that a mobile terminal network communications interface have to be added to the cameras  100   a - 100   f.    
         [0078]    The output sub-apparatus can be a TV set, or other suitable equipment, adapted to show image data from a number of cameras simultaneously, which TV set is adapted to receive image data broadcasted from the cameras  100   a - 100   f , which implies that a broadcasting interface is, in this alternative approach, added to each of the cameras  100   a - 100   f.    
         [0079]    In order to relate the information transmitted from the input sub-apparatus to a specific function, references are added in the image data shown by the output sub-apparatus. 
         [0080]      FIG. 4  illustrates an example of a Graphical User Interface (GUI)  400  of the apparatus according to the present invention. 
         [0081]    The GUI comprises a parameter values part  402 . In this part, the available parameter values are indicated, and a control button for each of the parameter values is available for adjustment of the respective parameter values. In this example, the control button is embodied as a slider, where the rightmost position implies a high parameter value and the leftmost position implies a low parameter value. 
         [0082]    In an image data part  404 , the image data from a number of cameras is shown simultaneously. In this example, image data from four different cameras is shown in four different image data areas  420   a ,  420   b ,  420   c ,  420   d.    
         [0083]    For instance, the image data areas  420   a ,  420   b ,  420   c ,  420   d  may represent image data from the cameras  100   a ,  100   b ,  100   c  and  100   d , respectively. 
         [0084]    A frame  406   a ,  406   b ,  406   c ,  406   d  can be placed around each of the image data areas  420   a ,  420   b ,  420   c ,  420   d . The image data area can be activated  420   c , illustrated in the figures with dashed lines, or deactivated  420   a ,  420   b ,  420   d . When an image data area  420   c  is activated, the changes made in the parameter values part  402  will be applied to the camera represented by this activated image data area  420   c  when the new parameter values are transmitted to the cameras. 
         [0085]    The image data may comprise a text or symbol  407 , such as company name or a logo. The text  407  can be added to the image data by a user. When the text  407  is added to the image data from a specific camera, it can be shown in the image data part  404 . 
         [0086]    Advantageously, the text  407  is stored in the memory  206  of the camera  100 . In this way, regardless of which apparatus that is used for displaying the image data, the text will be shown. Further, the transparency of the text or logo may be one of the parameter values. 
         [0087]    Further, an update image data checkbox  422   a ,  422   b ,  422   c ,  422   d  may be associated to each of the image data areas  420   a ,  420   b ,  420   c ,  420   d . When the checkbox is activated  422   b ,  422   c  the image data in the associated image data area  420   b ,  420   c  is set to be updated with new image data when new image data is requested, i.e. the cameras corresponding to the image data areas  420   b ,  420   c  are set to belong to a second subset of cameras which will be further described in  FIGS. 6 ,  7 ,  8  and  9 . 
         [0088]    Advantageously, since an image feedback most often is preferred after having changed the parameter values, the checkbox  422   c  may be automatically activated when the frame  420   c  around a certain image data area  406   c  is activated. 
         [0089]    In order to facilitate and improve the parameter values, a number of templates, i.e. a set of parameter values for a certain environment, is available. The templates are presented in a template area  408 , and a current template  410  can be indicated as darker than the rest of the templates. 
         [0090]    A button area  412  comprising a “set text/logo” button  414 , an “update images” button  416  and a “done” button  418  is presented. 
         [0091]    The “set text/logo” button  414  is utilised for setting the text or the logo  407 . When the button  414  is pressed a new window can be shown, where a set of tools is presented for creating a text or logo, or a dialog box can be shown where a file containing a text or logo can be chosen and thereafter be set as the text or logo  407 . After the text or logo  407  has been created or chosen, it may be stored temporarily in the apparatus  104  in order to be transmitted to the camera/cameras  100   a - 100   f  together with the parameter values. Alternatively, the text or logo  407  is transmitted instantly to the camera/cameras  100   a - 100   f.    
         [0092]    The “update images” button  416  is utilised for updating the parameter values in the camera/cameras  100   c  corresponding to the activated frame/frames  406   c  and for downloading new image data from the camera/cameras  100   b , 100   c  corresponding to the activated update image data checkboxes  422   b ,  422   c.    
         [0093]    More specifically, in a first step, the new parameter values, which are set with the sliders in the parameter values part, are transmitted to the camera/cameras being indicated via the frames  406   a - 406   d . Next, the new parameter values are received by the camera/cameras and the present parameter values stored in the memory of the camera  206  are replaced by the received new parameter values. In the case illustrated in  FIG. 4 , only the parameter values in the camera  100   c  is indicated to be updated. 
         [0094]    In a second step, new image data is retrieved from the cameras being indicated via the update image checkboxes  422   b ,  422   c . For instance, this may be made by sending an image request to the indicated camera/cameras, in this case the cameras  100   b ,  100   c.    
         [0095]    In this way, when a parameter value change is made, the “update images” button  416  can be pressed, and a result of the parameter value change is shown. Hence, an image feedback is automatically given for every change, which is an advantage. Moreover, image feedback may be given for every chosen camera connected to the data communications network, which means that if the appearance of the image data for a number of cameras is not similar, this will easily be noticed by the user. 
         [0096]    An appropriate way to work is to first set a template to each of the cameras, e.g. the two middlemost image data areas  420   b ,  420   c  in  FIG. 4  present image data from an outdoor environment and are hence related to a template corresponding to the an outdoor environment. Thereafter, based on the outdoor environment template, a fine adjustment of the parameter values can be made manually by adjusting the parameter value slides in the parameter values part  402 . 
         [0097]    When the image data areas  420   a ,  420   b ,  420   c ,  420   d  are considered to have a similar appearance, the “Done” button  418  is pressed, which can be seen as a user acceptance signal. 
         [0098]    A General Method for Configuring Parameter Values For a Number of Cameras 
         [0099]      FIG. 5  shows a flow chart illustrating the general steps of a method for configuring parameter values for a number of cameras according to the present invention, reference is also made to details of  FIGS. 1 and 3 . 
         [0100]    In a first step  500 , a connection is set up between the apparatus  104  and the cameras  100   a - 100   f . This connection can be set up through the data communications network  102 . 
         [0101]    In a second step  502 , test image data and parameter values are acquired by the apparatus  104  from the cameras  100   a - 100   f.    
         [0102]    In a third step  504 , the acquired test image data and parameter values are shown on the display  300  of the apparatus  104 . 
         [0103]    In a fourth step  506 , it is investigated whether the acquired image data from the cameras  100   a - 100   f  have a similar appearance, e.g. that a specific green object is represented with the same green colour in the image data from each of the cameras  100   a - 100   f.    
         [0104]    This fourth step  506  can be performed manually by the user of the apparatus  104 . For instance, by using a GUI as is described in  FIG. 4 . 
         [0105]    Alternatively, this fourth step  506  is made automatically, e.g. the apparatus determines a reference camera, and adjusts the remaining cameras in accordance with the reference camera. 
         [0106]    This can be done by choosing reference image data originating from the reference camera, calculating a number of characteristic values for the reference image data, such as the mean red value, comparing the characteristic values of the reference image data with the corresponding characteristic values of the image data originating from one or several of the other cameras, calculating a correction value, or values, based on the comparison, and changing the parameter values in the one or several other cameras in accordance with the correction value. 
         [0107]    If the image data from the cameras  100   a - 100   f  is considered to have a similar appearance, the parameter values are configured correctly, and conversely, if the image data from the cameras  100   a - 100   f  are not considered to have a similar appearance, the method enters a fifth step  508 . 
         [0108]    In the fifth step  508 , the parameter values are changed. This can be made by choosing a template, or by configuring each of the parameter values separately. 
         [0109]    In a sixth step  510 , the updated parameter values are transmitted to the cameras  100   a - 100   f.    
         [0110]    Thereafter, in a seventh step  512 , the parameter values of the cameras are updated in accordance with the received changed parameter values. 
         [0111]    Next, the method is repeated from the second step  502 , i.e. test image data are acquired once again, and so on, until the image data from the cameras is considered to have a similar appearance. 
         [0112]    Since the changed parameter values are transmitted from the apparatus  104  to the cameras  100   a - 100   f  in the sixth step  510 , the changed parameter values does not necessarily have to be acquired from the cameras  100   a - 100   f  when the second step  502  is repeated. However, if many users are able to change the parameter values of the cameras  100   a - 100   f , there may be a good reason to acquire the changed parameter values. 
         [0113]    To sum up, the method is an iterative method, which means that the steps of the method will be repeated until the user, or the apparatus, considers the image data from the cameras to have a similar appearance. Essentially, an unlimited number of iterations can be made. 
       Four Embodiments 
       [0114]      FIGS. 6 ,  7 ,  8  and  9  illustrate a first, a second, a third and a fourth embodiment of the present invention, respectively. In all the embodiments, six different cameras  100   a - 100   f  are available and connected to the apparatus  104  in accordance with  FIG. 1 . The actual number of cameras may be less than or more than six in other embodiments. 
         [0115]    Generally, in all of the embodiments, image data is initially received from all of the cameras  100   a - 100   f  and is shown on the display  300 . Then, a first subset comprising some of the cameras is not considered to have image data with the same appearance as the image data of the remaining cameras, whereas the parameter values of the cameras included within the first subset are changed. Thereafter, changed image data is acquired from a second subset comprising at least the cameras of the first subset. 
         [0116]    In the first embodiment, illustrated in  FIG. 6 , the first subset  600  comprises the cameras  100   a - 100   b  and the second subset  602  comprises the cameras  100   a - 100   d.    
         [0117]    By including more cameras in the second subset than in the first subset, image data from cameras with changed parameter values as well as image data from cameras with unchanged parameter values are generated at the same point of time. This implies that the conditions are improved for the decision whether the image data is similar or not. 
         [0118]    For instance, if the cameras  100   a - 100   d , i.e. the second subset, are monitoring a room, and a light is being lit in the room, the configuration of parameter values will not be disturbed, since all sets of image data from cameras  100   a - 100   d  are generated at the same point of time, either before the light is being lit or after the light is being lit. 
         [0119]    The reason for not including the cameras  100   e - 100   f  in the second subset can be that the lighting conditions of the environments being monitored by the cameras  100   e - 100   f  differ strongly from the environments being monitored by the cameras  100   a - 100   d  included in the second subset  602 . 
         [0120]    For instance, the environments being monitored by the cameras  100   a - 100   d  included in the second subset  602  may be indoor environments, and the environments being monitored by the cameras  100   e - 100   f  may be environments illuminated by an IR light. 
         [0121]      FIG. 7  illustrates the second embodiment. In this embodiment a first subset  700 , as well as a second subset  702 , comprises the cameras  100   a - 100   b.    
         [0122]    This embodiment can be relevant if the cameras  100   a - 100   b  are the only ones monitoring a certain lighting environment and none of the cameras  100   a - 100   b  have proper parameter values. 
         [0123]      FIG. 8  illustrates a third embodiment. In this embodiment, a first subset  800  comprises the cameras  100   a - 100   b  and a second subset  802  comprises all of the cameras  100   a - 100   f.    
         [0124]    This embodiment can be relevant if all of the cameras are monitoring environments with the same lighting conditions and the cameras  100   a - 100   b  are the only ones not having proper parameter values. 
         [0125]      FIG. 9  illustrates a fourth embodiment. In this embodiment, a first subset  900 , as well as a second subset  902 , comprises all of the cameras  100   a - 100   f.    
         [0126]    If all of the cameras are not having proper parameter values, this embodiment can be relevant. 
         [0127]    An advantage of having the first subset  600 / 700 / 800 / 900  and the second subset  602 / 702 / 802 / 902 , respectively, is that only the required image data is transmitted from the cameras  100   a - 100   f  to the apparatus  104  during the configuration of parameter values. This implies less unnecessary usage of the datacommunications network  102 . 
         [0128]    If the present invention is realised as a computer program, it can be made in such a way that it is possible for the user to determine the first and second subset easily. For instance, this can be realised by having checkboxes  422   a ,  422   b ,  422   c ,  422   d  associated to each of the cameras  100   a - 100   d , which checkbox indicates whether each camera is associated to the second subset  602 / 702 / 802 / 902  or not. If the parameter values for a camera is changed, the camera can be automatically associated to the first subset  600 / 700 / 800 / 900 , as well as the second subset  602 / 702 / 802 / 902 . 
         [0129]    A Method for Configuring Parameter Values 
         [0130]    According to another aspect, the method for configuring parameter values for a plurality of cameras may be described with reference to  FIG. 10 . The steps of this method may be performed in the apparatus  104 . 
         [0131]    In a first step  1000 , image data is acquired from the plurality of cameras  100   a - 100   f.    
         [0132]    In a second step  1002 , the image data is buffered. 
         [0133]    In a third step  1004 , the image data is displayed. 
         [0134]    In a fourth step  1006 , at least one parameter value is changed for a first subset of cameras  600 / 700 / 800 / 900 . 
         [0135]    In a fifth step  1008 , the at least one parameter value is transmitted to the first subset of cameras  600 / 700 / 800 / 900 . 
         [0136]    In a sixth step  1010 , changed image data is acquired from a second subset of cameras  602 / 702 / 802 / 902 . 
         [0137]    In a seventh step  1012 , the buffered image data for the second subset of cameras  602 / 702 / 802 / 902  is replaced with the changed image data for the second subset of cameras  602 / 702 / 802 / 902 . 
         [0138]    Finally, in an eighth step  1014 , the image data for the plurality of cameras  100   a - 100   f  is displayed. 
         [0139]    A Method for Parameter Configuration of a Camera 
         [0140]    A method for parameter value configuration of a camera  100  coupled to an apparatus  104  through a data communications network  102  will now be described with reference to  FIG. 11 . The steps of this method will be performed in the camera. 
         [0141]    In a first step  1100 , an image data request from the apparatus  104  is received by the camera  100 . 
         [0142]    In a second step  1102 , image data is generated by the camera  100 . 
         [0143]    In a third step  1104 , the image data is transmitted from the camera  100  to the apparatus  104 . 
         [0144]    In a fourth step  1106 , a parameter value change request from the apparatus  104  is received by the camera  100 . 
         [0145]    In a fifth step  1108 , the parameter values are changed based upon the parameter value change request. 
         [0146]    In a sixth step  1110 , new image data based on the changed parameter values is generated by the camera  100 . 
         [0147]    Finally, in a seventh step  1112 , the new image data is transmitted to the apparatus  104  through the data communications network  102 . 
         [0148]    The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.