Patent Publication Number: US-2023156141-A1

Title: Vehicular vision system with multiple cameras

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a division of U.S. Pat. Application Ser. No. 17/247,488, filed Dec. 14, 2020, now U.S. Pat. No. 11,553,140, which is a continuation of U.S. Pat. Application Ser. No. 15/899,105, filed Feb. 19, 2018, now U.S. Pat. No. 10,868,974, which is a continuation of U.S. Pat. Application Ser. No. 13/990,902, filed May 31, 2013, now U.S. Pat. No. 9,900,522, which is a 371 national phase application of PCT Application No. PCT/US2011/062834, filed Dec. 1, 2011, which claims the priority benefit of U.S. Provisional Applications, Ser. No. 61/482,786, filed May 5, 2011, and Ser. No. 61/418,499, filed Dec. 1, 2010. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to multi-camera systems for use in vehicles, and more particularly multi-camera systems for use in vehicles wherein image manipulation is carried out on the images prior to displaying the images to a vehicle occupant. 
     BACKGROUND OF THE INVENTION 
     There are few multi-camera systems currently available in vehicles. Such systems incorporate four cameras typically, and provide a vehicle occupant with a composite image that is generated from the images taken by the four cameras. However, such systems can require a relatively large amount of processing power to generate the image that is displayed to the vehicle occupant, particular in situations where there is manipulation of the images being carried out. Such manipulation of the images may include dewarping, among other things. 
     It would be beneficial to provide a multi-camera system for a vehicle that requires relatively little processing power. 
     SUMMARY OF THE INVENTION 
     In a first aspect, the invention is directed to a method of establishing a composite image for displaying in a vehicle, comprising: 
     [0006] a) providing a first camera and a second camera, each camera having a field of view;   [0007] b) positioning the cameras so that the fields of view of the cameras overlap partially, wherein the cameras together have a combined field of view;   [0008] c) recording preliminary digital images from the cameras, each preliminary digital image being made up of a plurality of pixels; and   [0009] d) generating a final composite digital image that corresponds to a selected digital representation of the combined field of view of the cameras by remapping selected pixels from each of the preliminary digital images into selected positions of the final composite digital image.   

     In a second aspect, the invention is directed to a method of establishing a composite image for displaying in a vehicle, comprising: 
     [0011] a) providing a first camera and a second camera, a third camera and a fourth camera, each camera having a field of view, wherein the cameras together have a combined field of view that is a 360 degree field of view around the vehicle;   [0012] b) positioning the cameras so that the field of view of each camera overlaps partially with the field of view of two of the other cameras;   [0013] c) recording preliminary digital images from the cameras, each preliminary digital image being made up of a plurality of pixels; and   [0014] d) generating a final composite digital image that corresponds to a selected digital representation of the combined field of view of the cameras by remapping selected pixels from each of the preliminary digital images into selected positions of the final composite digital image,   
   wherein the preliminary digital images each have associated therewith a preliminary apparent camera viewpoint and the final composite digital image has associated therewith a final apparent camera viewpoint,   and wherein the selected pixels from the preliminary digital images are selected so that the final apparent camera viewpoint associated with the final composite digital image is higher than the preliminary apparent camera viewpoints associated with the preliminary digital images,   and wherein the selected pixels from the preliminary digital images are selected so that any misalignment between the overlapping portions of the preliminary digital images is substantially eliminated,   and wherein the selected pixels from the preliminary digital images are selected so that the final composite digital image is dewarped as compared to each of the preliminary digital images.   

     In a third aspect, the invention is directed to a system for establishing a composite image for displaying in a vehicle, comprising a first camera and a second camera and a controller. Each camera has a field of view that overlaps partially with the field of view of the other camera. Each camera has an imager for generating a preliminary digital image. The cameras together have a combined field of view. The controller is programmed to generate a final composite digital image that corresponds to a selected digital representation of the combined field of view of the cameras by using a remapping table to remap selected pixels from each of the preliminary digital images into selected positions of the final composite digital image. 
     In a fourth aspect, the invention is directed to a method of generating a remapping table for use in mapping pixels from a plurality of preliminary digital images into a final composite image, comprising: 
     [0021] a) driving a vehicle having a first camera and a second camera thereon, each camera having a field of view that overlaps partially with the field of view of the other camera, each camera having an imager for generating one of the preliminary digital image, wherein the cameras together have a combined field of view, wherein the vehicle further includes a controller;   [0022] b) detecting a target feature along the path of the vehicle during driving, using the controller;   [0023] c) providing a first preliminary digital image from the first camera, wherein the first preliminary digital image contains a first representation of the target feature at a first point time;   [0024] d) determining the position of the first representation of the target feature in the first preliminary digital image;   [0025] e) providing a second preliminary digital image from the second camera, wherein the second preliminary digital image contains a second representation of the target feature at a second point time;   [0026] f) determining the position of the second representation of the target feature in the second preliminary digital image;   [0027] g) comparing the positions of the first and second representations of the target feature; and   [0028] h) generating at least one value for the remapping table based on the result of the comparison in step g).   

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described by way of example only with reference to the attached drawings, in which: 
         FIG.  1    is a plan view of a vehicle with a camera system in accordance with an embodiment of the present invention; 
         FIG.  2    is a schematic illustration of the camera system shown in  FIG.  1   ; 
         FIGS.  3   a - 3   d    are images taken by cameras that are part of the camera system shown in  FIG.  1   ; 
         FIG.  4    is a magnified view of the image shown in  FIG.  3   d   ; 
         FIG.  5    is a composite final image generated by the camera system shown in  FIG.  1   ; 
         FIG.  6   a    is remapping table used to generate the final composite image shown in  FIG.  5    from the images shown in  FIGS.  3   a - 3   d   ; 
         FIG.  6   b    is a graphical representation of the remapping that takes place using the remapping table shown in  FIG.  6   a   ; 
         FIG.  6   c    is a graphical representation of a step that takes place prior to the remapping illustrated in  FIG.  6   b   ; 
         FIG.  7    is a plan view of a vehicle in a test area use to calibrate the camera system shown in  FIG.  1   ; 
         FIG.  8   a    is a preliminary image from a camera from the camera system shown in  FIG.  1   ; 
         FIGS.  8   b  and  8   c    are images formed by progressive remapping of the image shown in  FIG.  8   a   ; 
         FIG.  8   d    illustrates the analysis performed by the camera system shown in  FIG.  1   , to stitch together several remapped images; 
         FIG.  8   e    is a final composite image generated using the analysis shown in  FIG.  8   d   ; 
         FIGS.  9   a - 9   c    are remapping tables used to generate the images shown in  FIGS.  8   b ,  8   c  and  8   e    from the preliminary image shown in  FIG.  8   a   ; 
         FIG.  10    shows target features on a road that can be used to assist in calibrating the camera system shown in  FIG.  1    during driving; 
         FIG.  11    is a composite image formed using default remapping values, prior to the calibration of the camera system shown in  FIG.  1    during drive; and 
         FIGS.  12   a - 12   c    are illustrations of events that would trigger adjustment of the remapping values used to generate the composite image shown in  FIG.  3   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is made to  FIG.  1   , which shows a vehicle  10  that includes a vehicle body  12 , and a multi-camera system  14  in accordance with an embodiment of the present invention. The multi-camera system  14  includes four cameras  16  and a controller  18 . The multi-camera system  14  is configured to display a composite image that is generated using all four cameras  16  on an in-cabin display, shown at  20  in  FIG.  2   . The four cameras  16  include a front camera  16 F, a rear camera  16 R, and driver’s side and passenger side cameras  16 D and  16 P. 
     Referring to  FIG.  1   , each camera  16  has a field of view  22 . The field of view of each camera  16  overlaps with the fields of view  22  of the two cameras  16  on either side of it. Preferably, the field of view of each camera  16  is at least about 185 degrees horizontally. Referring to  FIG.  2   , each camera  16  includes an image sensor  24 , which is used to generate a digital image taken from the camera’s field of view  22 . The image sensor  24  may be any suitable type of image sensor, such as, for example a CCD or a CMOS image sensor. 
     The digital image generated from the image sensor  24  may be referred to as a preliminary digital image, an example of which is shown at  26  in  FIGS.  3   a - 3   d   .  FIGS.  3   a - 3   d    show the preliminary digital images  26  from the four cameras  16 . The images  26  are correspondingly identified individually at  26 F,  26 R,  26 D and  26 P. 
     Each preliminary digital image  26  is made up of a plurality of pixels, which are shown at  28  in the magnified image shown in  FIG.  4   . It will be noted that the pixels  28  are enlarged in  FIG.  4    for the sake of clarity. The actual image sensor  24  may have any suitable resolution. For example it may generate a digital image that is 640 pixels wide by 480 pixels high, or optionally an image that is 720 pixels wide × 480 pixels high, or an image that is 1280 pixels wide × 960 pixels high or even higher. The output signals from the cameras  16  to the controller  18  may be in analog form such as in NTSC or PAL format, or in digital form using, for example LVDS format, or Ethernet. 
     The controller  18  is programmed to generate a final composite digital image, shown at  30  in  FIG.  5   , that corresponds to a selected digital representation of the combined field of view of the cameras  16  by using a remapping table  32  shown in  FIG.  6   a    to remap selected pixels  28  from each of the preliminary digital images  26  into selected positions of the final composite digital image  30 . 
     The digital representation may incorporate one or more operations on the original preliminary digital images  26 . For example, the pixels  28  from the original images  26  may be remapped in such a way as to dewarp the images  26 . As can be seen in  FIG.  5   , the warpage present in the images  26  is reduced (in this case it is substantially eliminated) in the final composite digital image  30 . 
     Another operation that may be carried out through the remapping is viewpoint adjustment. Each preliminary digital image  26  has associated therewith, an apparent viewpoint, which is the viewpoint from which the camera  16  appears to have captured the image  26 . In the preliminary digital images  26 , the apparent viewpoint of the camera  16  is the same as the actual viewpoint of the camera  16  because no manipulation of the image  26  has been carried out. However, it may be preferable, when presenting a 360 degree view around the vehicle to the vehicle driver, to present a bird’s eye view. To accomplish this, the perspective of the image is adjusted by adjusting the relative sizes of portions of the preliminary images when remapping them to the final composite image  30 . For example, the objects that are closer to the camera  16  appear larger in the image  26  than objects that are farther from the camera  16 . After the apparent viewpoint has been raised however, as shown in the final digital image  30 , objects closer to the camera  16  are shrunk so that they are not larger than objects farther from the camera  16 . 
     A graphical representation of the remapping that is carried out is shown in  FIG.  6   b   . In the exemplary embodiment of the present invention, the preliminary digital images  26  were of sufficiently high resolution as compared to the resolution of the final composite image  30  that there is not a need for the controller to ‘stretch’ portions of the preliminary images  26  when generating the map for pixels in the final image  30 . In other words, in this particular embodiment, the controller  18  is not required to process a row of 10 pixels from the preliminary image  26  and convert it to a row of 20 pixels in the final image  30 . Thus, no pixels in the final image  30  are ‘fabricated’ or generated by the controller  18 . Put another way, the preliminary images  26  are of sufficiently high resolution that the image manipulation that is carried out to arrive at the final composite image  30  involves varying amounts of compression of portions of the preliminary image (i.e. removing or skipping pixels), but does not involve stretching of any portions of the preliminary image (which could involve interpolating between pixels and thus ‘creating’ pixels). It is conceivable, however, that the preliminary images would be of relatively lower resolution such that the controller  18  would be relied upon in some instances to stretch portions of the preliminary images  26  when creating the final composite image  30 . It will be noted that in the exemplary embodiment, the resolution of each of the preliminary images is 720 pixels wide by 480 pixels high, while the resolution of the final composite image is about 320 pixels wide by 480 pixels high. As can be seen in the image in  FIGS.  5  and  6   b   , a representation of the vehicle  10  itself is inserted in the final composite image  30 . While it is preferred that none of the pixels in the final image  30  be ‘created’ through interpolation between adjacent pixels, it is contemplated that in certain situations some pixels may be generated that way (i.e. by interpolating between adjacent pixels) so as to provide a relatively smooth transition between them. 
     Referring to  FIG.  5   , in the exemplary embodiment, given that the final composite image  30  is only 320 pixels wide, a somewhat-dewarped rear view is also displayed on the display  20  for the vehicle driver, adjacent the 360 degree view. 
     Referring to  FIG.  6   c   , in some cases, the portion of the preliminary digital image  26  from each individual camera that is used as part of the final composite image  30  may be a selected subset of the pixels of the preliminary digital image  26 . The particular subset used from each preliminary digital image is shown in a dashed box shown at  29  and will vary in position from camera to camera. It will be noted that the dashed box represents the subset of pixels of the associated preliminary digital image  26  that is involved in the generation of image  30 , which, for greater certainty, is not to say that each pixel from subset  29  necessarily will be a pixel in the image  30  – rather it is to say that the image  30  contains pixels that relate to or are taken from portion  29  and not to the portion of the preliminary digital image that is outside portion  29 . The rest of the image pixels (i.e. the pixels that are outside the portion  29  that is used to generate the composite image  30 ) are not needed and can be discarded. Only the pixels in the portions  29  are streamed into the memory of the image engine (which is what the module involved in generating the composite image  30  using the methods described herein may be referred to). By discarding those pixels that are outside the portions  29 , the memory bandwidth in image engine can be reduced, so that a slower memory can be utilized which may advantages in terms of reducing system cost, and/or increasing reliability. 
     Aspects of the calibration of the multi-camera system  14  will now be discussed. This calibration is used in order to assist in determining the remapping values in the remapping table  32  ( FIG.  6   a   ). 
     Initially, the cameras  16  are mounted to the vehicle body  12  and the vehicle  10  is positioned at a location (as shown in  FIG.  7   ) whereat there is a predetermined test arrangement  34  of alignment landmarks  36 , and dewarping landmarks  38 . 
     In the exemplary test arrangement  34  shown in  FIG.  7   , it can be seen that the landmarks  38  are straight lines. The preliminary digital image from one of the cameras  16   (e.g., the rear camera) is shown at  40  in  FIG.  8   a   . Three functions are carried out on the preliminary digital images  40  to prepare the final composite image  30  shown in  FIG.  8   e   . The functions are: dewarping, viewpoint adjustment, and offset correction. These functions may be carried out sequentially, and an intermediate remapping table may be generated in association with each function. Referring to  FIG.  8   a   , it can be seen that there is substantial warping in the representations  42  of the landmarks  38  in the preliminary digital image  40 . Knowing that the actual landmarks  38  are straight lines, this warping can be compensated for when determining the remapping of the pixels from the preliminary digital image  40  into the dewarped intermediate image shown at  44  in  FIG.  8   b   . As can be seen, the representations shown at  45  of the landmarks  38  are dewarped substantially completely. The remapping necessary to generate the dewarped image  44  may be stored in a first intermediate remapping table shown at  46  in  FIG.  9   a   . It will be understood that a preliminary digital image  40  from each camera  16  will be dewarped to generate a dewarped image  44  and so four first intermediate remapping tables  46  will be generated (i.e. one table  46  for each camera  16 ). 
     The dewarped image  44  may then be viewpoint adjusted so as to move the apparent viewpoint of the camera  16  upwards to generate a resulting ‘dewarped and viewpoint-adjusted’ image  48  in  FIG.  8   c   , using a second intermediate remapping table shown at  49  in  FIG.  9   b   . The remapping data to be inserted in the second intermediate remapping table  49  may be generated relatively easily by determining what adjustments need to be applied to the longitudinal representations  45   a  to make them parallel to each other, what adjustments need to be applied to the transverse representations  45   b  to make them parallel to each other (in this case virtually no adjustment in that regard is required), what adjustments need to be applied to the representations  45  so that they are spaced appropriately from each other, and to make the longitudinal representations  45   a  extend perpendicularly to the transverse representations  45   b , so as to match the known angles at which the actual longitudinal landmarks  38  intersect with the actual transverse landmarks  38 . It will be understood that each image  44  will be viewpoint-adjusted to generate a dewarped and viewpoint-adjusted image  48  and so four second intermediate remapping tables  49  will be generated. The representations of the landmarks  38  in  FIG.  8   c    are shown at  50 . 
     The dewarped and viewpoint-adjusted image  48  shown in  FIG.  8   c    from one camera  16  may be compared to the other dewarped and viewpoint-adjusted images  48  from the other cameras  16  to determine whether there is any offset adjustment necessary. This comparison is illustrated in  FIG.  8   d   . The versions of the images  48  shown in  FIG.  8   d    have been greatly simplified and only include a few representations  50  of landmarks  38  and representations  54  of landmarks  36 , so as to facilitate explanation and illustration of the comparison that is being carried out. It will be understood however, that the actual comparison that is carried out may be done with all of the representations  50  in the images  48  shown in  FIG.  8   c   . 
     As can be seen in  FIG.  7   , the alignment landmarks  36  are arranged in groups  52 , shown individually at  52   a ,  52   b ,  52   c  and  52   d . Each group  52  is visible to at least two of the cameras  16 . As shown in  FIG.  8   d   , each image  48  contains representations  53  of some of the alignment landmarks  36 . The groups of representations are identified at  54 . It can be seen that the images shown at  48 F (front) and  48 D (driver’s side) both contain representations  54  of the group  52   a  of landmarks  36 . Similarly the images shown at  48 F and  48 P (passenger side) both contain representations  54  of the group  52   b  of landmarks  36 . Similarly the images shown at  48 P and  48 R (rear) both contain representations  54  of the group  52   c  of landmarks  36 . Finally, the images shown at  48 R and  48 D both contain representations  54  of the group  52   d  of landmarks  36 . An X axis and a Y axis are shown at  56  and  58  respectively in  FIG.  8   d   . The X axis and Y axis offsets between the representations  54  of group  52   a  in image  48 F and the representations  54  of group  52   a  in image  48 D are determined, and these offsets can be taken into account when remapping pixels from these two images  48  into the final composite image  30  shown in  FIG.  8   e    to ensure that the final composite image  30  transitions smoothly from pixels taken from image  48 F to pixels taken from image  48 D. Similarly, the offsets can easily be determined between the representations  54  shown in any two adjacent images  48 , and this information can be taken into account when remapping the pixels from the images  48  into the final composite image  30 . The remapping information from the images  48  to the final composite image  30  may be stored in a third intermediate remapping table  60  shown in  FIG.  9   c   . It will be understood that only a single remapping table  60  is generated, which remaps pixels from each of the four images  48  into the final composite image  30 . 
     Once the four first remapping tables  46 , the four second remapping tables  49  and the third remapping table  60  are generated, the remapping table  32  shown in  FIG.  6   a    can be generated by combining the remapping information in all these tables  46 ,  49  and  60 . Once generated, the remapping table  32  may be stored in the permanent storage memory (shown at  80  in  FIG.  2   ) that is part of the camera system  14 . 
     However, the controller  18  may additionally store one or more of the individual remapping tables for use in generating and displaying an intermediate image. For example, it may be desired to show a dewarped rear view from the vehicle  10  in some instances, such as when the driver is backing the vehicle  10  up. The preliminary digital image  40  from the rear camera  16  can be remapped quickly and easily using the first intermediate remapping table  46  to generate the dewarped rear view image  44 . Other viewing modes are also possible and would benefit from having one or more of the intermediate remapping tables stored in the memory  80 . For example, a split view showing images from the driver’s side and passenger side cameras could be provided. 
     In the above example, the test arrangement  34  of landmarks  36  and  38  were provided as images painted on the floor of an indoor test area. It will be noted that other means of providing the test arrangement  34  can be provided. For example, the test arrangement can be provided on mats place on the floor of the test area. Alternatively, the test arrangement  34  could projected on the floor of the test area using any suitable means, such as one or more lasers, or one or more projectors, or some combination of both. 
     In the example described above, four cameras are used to generate a 360 degree view around the vehicle, using pixel remapping. It will be understood that the advantages of pixel remapping are not limited to camera systems that employ four cameras. For example, in an alternative embodiment that is not shown, the vehicle may include cameras  16  mounted at each of the front corners and each of the rear corners of the vehicle. Depending on whether the vehicle is leaving a parking spot by driving forward or by backing up, the two front corner cameras or the two rear corner cameras could be used to form a view that shows cross-traffic in front and to the sides of the vehicle, or behind and to the sides of the vehicle depending on whether the vehicle is driving forward or backing up. In such an embodiment, a final composite image can be generated using pixel remapping, but would be generated based on images from only two cameras (i.e. the cameras at the two front corners of the vehicle, or alternatively the cameras at the rear two corners of the vehicle). 
     It will be noted that, while the lines  38  in the test arrangement have been shown as straight lines, they need not be. They may be any suitable selected shape, which is then compared to its representation in the images  40  and  44  to determine how to remap the pixels to reduce warping and to carry out viewpoint adjustment. 
     In the test arrangement  34  shown in  FIG.  7    the alignment landmarks  36  are the intersections between the lines  38 . It will be understood however that the alignment landmarks could be other things, such as, for example, a group of unconnected dots arranged in a selected arrangement (e.g., arranged to form a square array). 
     The above description relates to the calibration of the camera system  14  in a controlled environment using a test arrangement  34  to generate the remapping table  32  for storage in the memory  80 . 
     It may be desirable to permit the controller  18  to calibrate or recalibrate the camera system  14  during driving. To do this, the controller  18  identifies a target feature that appears in an image from one of the cameras  16 . The target feature is shown in  FIG.  10    at  61  and may be, for example, a crack in the pavement, a lane marker or a piece of gravel. In  FIG.  10    numerous examples of possible target features are shown, although the controller  18  need only work with one target feature  61  that will pass on one side of the vehicle, in order to calibrate three of the cameras  16  to each other (i.e. the front camera, the camera on whichever side of the vehicle that the target feature  61  will pass, and the rear camera). At least one target feature  61  needs to be identified that will pass on the other side of the vehicle  10  (although not necessarily at the same time as the first target feature  61 ), in order to calibrate the camera on the other side of the vehicle to the other three cameras. 
     As the vehicle  10  is driven (preferably below a selected speed) past the target feature  61 , the target feature  61  moves through the field of view of the front camera  16 , through the field of view of one of the side cameras  16  and finally through the field of view of the rear camera  16 . A representation of the target feature  61  will thus move through images from the front camera  16 , then through images from one of the side cameras  16 , and then through images from the rear camera  16 . By analyzing the movement of the representation of the target feature  61  (e.g. its position, its direction of travel and its speed of movement) particularly as it transitions from images from one camera into the images from a subsequent camera the controller  18  can determine X and Y offsets, angular offsets, differences in scale, and possibly other differences, between images from one camera and another. This analysis may be carried out as follows: The controller  18  may start with a default set of remapping values for the remapping table  32  to generate a final composite image  30  from the four images. This default set of remapping values may be based on a simple algorithm to crop the preliminary digital images as necessary, rotate them as necessary and scale them as necessary to fit them in allotted zones  63  (shown individually at  63 F,  63 R,  63 D and  63 P) of a preliminary composite image  65  shown in  FIG.  11   . Optionally the default remapping values may also achieve dewarping and viewpoint adjustment, based on information obtained during testing in a test area similar to the test area shown in  FIG.  7   . Alternatively, the default remapping values may be the values in the remapping table  32  from a previous calibration (e.g. a calibration performed at a test area shown in  FIG.  7   , or a previous calibration performed during driving). As shown in  FIG.  11   , demarcation lines shown at  67  show the boundaries between the zones  63 . 
       FIGS.  12   a ,  12   b  and  12   c    show two adjacent zones  63  and the demarcation line  67  between them, to illustrate the analysis of the movement of the representation of the target feature  61 . The adjacent zones in  FIGS.  12   a ,  12   b  and  12   c   , are zones  63 D and  63 R. It will be understood however, that these figures are provided solely to illustrate the analysis that is carried out by the controller  18  on the movement of the representation of the target feature  61  between all applicable pairs of adjacent zones  63 . 
     In  FIGS.  12   a - 12   c   , the representation is shown at  69  and is shown at two different instants in time in each of the  FIGS.  12   a - 12   c   . The position of the representation  69  at the first, earlier instant of time is shown at  70   a , and at the second, later instant of time at  70   b . At the first instant in time, the representation  69  is in the zone  63 D. At the second instant of time, the representation  69  is in the zone  63 R. 
     While tracking the movement of the representation  69 , if the controller  18  detects that the representation  69  shifts horizontally by some amount of pixels (as shown in  FIG.  12   a   ) as it crosses the demarcation line  67  (by comparing the positions  70   a  and  70   b   of the representation  69  at the two instants in time), then the controller  18  can adjust the remapping values accordingly for one or both of the images that are mapped to the zones  63 D and  63 R. 
     With reference to  FIG.  12   b   , while tracking the movement of the representation  69 , the controller  18  may store an expected position  70   c  for the representation  69  at the second instant of time, based on the speed and direction of travel of the representation  69 . The controller  18  may compare the actual detected position  70   b  of the representation  69  at the second instant of time with the expected position  70   c  of the representation  69  at the second instant of time, and, if there is a vertical offset, the controller  18  can adjust the remapping values accordingly for one or both of the images that are mapped to the zones  63 D and  63 R. 
     With reference to  FIG.  12   c   , while tracking the movement of the representation  69 , if the controller  18  detects that the representation  69  changes its direction of travel by some angle as it crosses the demarcation line  67  (by deriving a first direction of travel based on positions  70   a  and  70   a ′, deriving a second direction of travel based on positions  70   b  and  70   b ′, and by comparing the two directions of travel), then the controller  18  can adjust the remapping values accordingly for one or both of the images that are mapped to the zones  63 D and  63 R. 
     It may be that only the remapping values associated with pixels in the immediate vicinity of the representation  69  are adjusted. Thus, the vehicle  10  may drive along while the controller  18  scans for and detects target features  61  at different lateral positions on the road, so that different portions of the remapping table  32  are adjusted. As an alternative way, the vehicle  10  may drive along while the controller  18  scans for and detects multiple target features  61  at different lateral positions across each demarcation line  67 . At a selected point in time (e.g., after having detected target features  61  over a selected amount of lateral positions along the demarcation line  67 ), the controller  18  may then determine a formula (or set of formulas) that could be used to remap the entire area along the demarcation line  67  as a whole, based on the changes in the positions of the representations  69 . Then the controller  18  uses that formula (or set of formulas) to remap the entire area around the border. For greater certainty the formula or formulas may be linear or nonlinear. 
     After detecting a target feature  61  at a particular lateral position on the road, and adjusting a portion of the remapping table  32  through the techniques described above, the controller  18  may also scan for and detect a second target feature  61  at approximately the same lateral position on the road and apply these techniques again, in order to improve the accuracy of the adjustments to the remapping values. 
     In many situations (e.g. after a malfunctioning or damaged camera has been replaced in the vehicle or simply due to a shift in the position of a camera over time in the vehicle) it may be that a camera is no longer in the same position and orientation as it was before. As a result, during the calibration procedure some pixels will require a change in their remapping due to new changes that occur to representations  69  as they cross demarcation lines  67 . If the changes to the remapping are only carried out in the immediate vicinity of the affected pixels then there will be a misalignment of those pixels with other pixels that are not changed. If the changes are made to all the pixels in an image  26  then this could cause a problem with the remapping of pixels at the other demarcation line  67  at the other end of the image  26 . To address this issue, when a new remapping is carried out on a selected pixel, the remapping is carried out in progressively diminishing amounts on a range of adjacent pixels. For example, if during a calibration it is determined that a particular pixel should be shifted 5 pixels laterally, a selected first number of pixels longitudinally adjacent to that pixel will be shifted 5 pixels laterally, a selected second number of pixels longitudinally adjacent to the first number of pixels will be shifted 4 pixels laterally, a selected third number of pixels adjacent to the second number of pixels will be shifted 3 pixels laterally, and so on until there is no lateral shift to carry out. This effectively smooths out the remapping of the pixels, as an example, in a car wherein the front camera is damaged in a traffic accident, and is replaced, a recalibration will be carried out, and the controller  18  may detect that the remapping that applied at the front left and right demarcation lines  67  does not work anymore. The controller  18  may determine a new remapping for these regions. However, the remapping that occurs at the rear left and right demarcation lines is still good, since the left, right and rear cameras have not been moved. To address this, the controller  18  may remap some selected number of pixels (e.g. 50 pixels), rearward of the newly remapped pixels along the front left and right demarcation lines  67  in groups by progressively smaller amounts eventually reducing the remapping to zero. No remapping of pixels takes place along the rear left and right demarcation lines  67 . 
     After a selected period of time of driving, or after detecting enough target features at enough lateral positions to ensure that a sufficient amount of adjustment of the remapping table has been made, the controller  18  may end the calibration process. 
     The particular cameras  16  that are used in the camera system  14  may be any suitable cameras. One example of an acceptable camera is a ReversAid camera made by Magna Electronics, an operating unit of Magna International Inc. of Aurora, Ontario, Canada. 
     The camera or vision system includes a display screen that is in communication with a video line and that is operable to display images captured by the camera or camera module. The display screen may be disposed in an interior rearview mirror assembly of the vehicle, and may comprise a video mirror display screen, with video information displayed by the display screen being viewable through a transflective mirror reflector of the mirror reflective element of the interior rearview mirror assembly of the vehicle. For example, the camera or camera module may be disposed at a rearward portion of the vehicle and may have a rearward facing field of view. The display screen may be operable to display images captured by the rearward viewing camera during a reversing maneuver of the vehicle. 
     Surround view / panoramic vision / birds-eye vision multi-camera systems are known, such as described in U.S. Pat. Nos. 6,275,754; 6,285,393; 6,483,429; 6,498,620; 6,564,130; 6,621,421; 6,636,258; 6,819,231; 6,917,378; 6,970,184; 6,989,736; 7,012,549; 7,058,207; 7,071,964; 7,088,262; 7,145,519; 7,161,616; 7,230,640; 7,248,283; 7,280,124; 7,295,227; 7,295,229; 7,301,466; 7,317,813; 7,369,940; 7,463,281; 7,468,745; 7,519,459; 7,592,928; 7,680,570; 7,697,027; 7,697,029; 7,742,070; 7,768,545 and/or 7,782,374, and/or U.S. Publication Nos. 2003/0137586; 2005/0030379; 2005/0174429; 2005/0203704; 2007/0021881; 2007/0165909; 2008/0036857; 2008/0144924; 2009/0179773 and/or 2010/0013930, and/or International Publication Nos. WO 2000/064175; WO 2005/074287; WO 2007/049266; WO 2008/044589; WO 2009/095901; WO 2009/132617; and/or WO 2011/014482, and/or European Pat. Publication Nos. EP1022903; EP1179958; EP1197937; EP1355285; EP1377062; EP1731366 and/or EP1953698, and/or MURPHY, TOM, “Looking Back to the Future – How hard can it be to eliminate a driver’s blindspot?”, Ward’s AutoWorld, May 1, 1998, which are all hereby incorporated herein by reference in their entireties. Such systems benefit from the present invention. 
     The video display is operable to display a merged or composite image to provide a panoramic or surround view for viewing by the driver of the vehicle. The vision system may utilize aspects of the vision and display systems described in U.S. Pat. Nos. 5,550,677; 5,670,935; 6,498,620; 6,222,447 and/or 5,949,331, and/or PCT Application No. PCT/US2011/061124, filed Nov. 17, 2011, and/or PCT Application No. PCT/US2010/025545, filed Feb. 26, 2010 and published on Sep. 2, 2010 as International Publication No. WO 2010/099416, which are hereby incorporated herein by reference in their entireties. 
     Optionally, the video display may display other images, and may display a surround view or bird’s-eye view or panoramic-view images or representations at the display screen, such as by utilizing aspects of the display systems described in PCT Application No. PCT/US10/25545, filed Feb. 26, 2010 and published Sep. 2, 2010 as International Publication No. WO 2010/099416, and/or PCT Application No. PCT/US10/47256, filed Aug. 31, 2010 and published Mar. 10, 2011 as International Publication No. WO 2011/028686, and/or U.S. Provisional Applications, Ser. No. 61/540,256, filed Sep. 28, 2011; Ser. No. 61/466,138, filed Mar. 22, 2011; Ser. No. 61/452,816, filed Mar. 15, 2011; and Ser. No. 61/426,328, filed Dec. 22, 2010, which are all hereby incorporated herein by reference in their entireties. Examples of bird’s eye view systems and associated techniques are described in U.S. Pat. Nos. 5,670,935; 6,636,258; 7,145,519; 7,161,616; 7,230,640; 7,248,283; 7,295,229; 7,301,466 and/or 7,592,928, and/or International Publication No. WO 2010/099416, published Sep. 2, 2010, and/or PCT Application No. PCT/US10/47256, filed Aug. 31, 2010 and published Mar. 10, 2011 as International Publication No. WO 2011/028686, which are hereby incorporated herein by reference in their entireties. Optionally, the camera and video display may operate to display other images, and may display a trailer angle or the like of a trailer behind the vehicle. 
     The vision display system may operate to display the rearward images at the video mirror display, and may do so responsive to the driver of the vehicle shifting the vehicle into a reverse gear (such as by utilizing aspects of the vision systems described in U.S. Pat. Nos. U.S. Pat. Nos. 5,550,677; 5,670,935; 6,498,620; 6,222,447 and/or 5,949,331, and/or PCT Application No. PCT/US2011/056295, filed Oct. 14, 2011, which are hereby incorporated herein by reference in their entireties). 
     Optionally, the system of the present invention may utilize aspects of the vision systems and lane departure systems and/or lane change aids and/or side object detection systems of the types described in U.S. Pat. Nos. 7,914,187; 7,720,580; 7,526,103; 7,038,577; 7,004,606; 6,946,978; 6,882,287 and/or 6,396,397, and/or PCT Application No. PCT/US2011/059089, filed Nov. 3, 2011, which are hereby incorporated herein by reference in their entireties. 
     The imaging sensor or camera that captures the image data for image processing may comprise any suitable camera or sensing device, such as, for example, an array of a plurality of photosensor elements arranged in 640 columns and 480 rows (a 640 × 480 imaging array), with a respective lens focusing images onto respective portions of the array. The photosensor array may comprise a plurality of photosensor elements arranged in a photosensor array having rows and columns. The camera or imaging sensor and/or the logic and control circuit of the imaging sensor may function in any known manner, such as by utilizing aspects of the vision or imaging systems described in U.S. Pat. Nos. 6,806,452; 6,690,268; 7,005,974; 7,123,168; 7,004,606; 6,946,978; 7,038,577; 6,353,392; 6,320,176; 6,313,454; 6,824,281; 5,550,677; 5,877,897; 6,498,620; 5,670,935; 5,796,094 and/or 6,396,397, and/or PCT Application No. PCT/US2010/028621, filed Mar. 25, 2010, which are all hereby incorporated herein by reference in their entireties. 
     The imaging device and control and image processor and any associated illumination source, if applicable, may comprise any suitable components, and may utilize aspects of the cameras and vision systems described in U.S. Pat. Nos. 5,550,677; 5,877,897; 6,498,620; 5,670,935; 5,796,094; 6,396,397; 6,806,452; 6,690,268; 7,005,974; 7,123,168; 7,004,606; 6,946,978; 7,038,577; 6,353,392; 6,320,176; 6,313,454 and 6,824,281, and/or International Publication No. WO 2010/099416, published Sep. 2, 2010, and/or PCT Application No. PCT/US10/47256, filed Aug. 31, 2010, and/or U.S. Pat. application Ser. No. 12/508,840, filed Jul. 24, 2009, and published Jan. 28, 2010 as U.S. Pat. Publication No. US 2010-0020170, which are all hereby incorporated herein by reference in their entireties. The camera or cameras may comprise any suitable cameras or imaging sensors or camera modules, and may utilize aspects of the cameras or sensors described in U.S. Pat. application Ser. No. 12/091,359, filed Apr. 24, 2008 and published Oct. 1, 2009 as U.S. Publication No. US-2009-0244361, and/or U.S. Pat. Nos. 7,965,336 and/or 7,480,149, which are hereby incorporated herein by reference in their entireties. The imaging array sensor may comprise any suitable sensor, and may utilize various imaging sensors or imaging array sensors or cameras or the like, such as a CMOS imaging array sensor, a CCD sensor or other sensors or the like, such as the types described in U.S. Pat. Nos. 7,965,336; 5,550,677; 5,670,935; 5,760,962; 5,715,093; 5,877,897; 6,922,292; 6,757,109; 6,717,610; 6,590,719; 6,201,642; 6,498,620; 5,796,094; 6,097,023; 6,320,176; 6,559,435; 6,831,261; 6,806,452; 6,396,397; 6,822,563; 6,946,978; 7,339,149; 7,038,577; 7,004,606 and/or 7,720,580, and/or PCT Application No. PCT/US2008/076022, filed Sep. 11, 2008 and published Mar. 19, 2009 as International Publication No. WO 2009/036176, and/or PCT Application No. PCT/US2008/078700, filed Oct. 3, 2008 and published Apr. 9, 2009 as International Publication No. WO 2009/046268, which are all hereby incorporated herein by reference in their entireties. 
     The camera module and circuit chip or board and imaging sensor may be implemented and operated in connection with various vehicular vision-based systems, and/or may be operable utilizing the principles of such other vehicular systems, such as a vehicle headlamp control system, such as the type disclosed in U.S. Pat. Nos. 5,796,094; 6,097,023; 6,320,176; 6,559,435; 6,831,261; 7,004,606; 7,339,149 and/or 7,526,103, which are all hereby incorporated herein by reference in their entireties, a rain sensor, such as the types disclosed in commonly assigned U.S. Pat. Nos. 6,353,392; 6,313,454; 6,320,176 and/or 7,480,149, which are hereby incorporated herein by reference in their entireties, a vehicle vision system, such as a forwardly, sidewardly or rearwardly directed vehicle vision system utilizing principles disclosed in U.S. Pat. Nos. 5,550,677; 5,670,935; 5,760,962; 5,877,897; 5,949,331; 6,222,447; 6,302,545; 6,396,397; 6,498,620; 6,523,964; 6,611,202; 6,201,642; 6,690,268; 6,717,610; 6,757,109; 6,802,617; 6,806,452; 6,822,563; 6,891,563; 6,946,978 and/or 7,859,565, which are all hereby incorporated herein by reference in their entireties, a trailer hitching aid or tow check system, such as the type disclosed in U.S. Pat. No. 7,005,974, which is hereby incorporated herein by reference in its entirety, a reverse or sideward imaging system, such as for a lane change assistance system or lane departure warning system or for a blind spot or object detection system, such as imaging or detection systems of the types disclosed in U.S. Pat. Nos. 7,881,496; 7,720,580; 7,038,577; 5,929,786 and/or 5,786,772, which are hereby incorporated herein by reference in their entireties, a video device for internal cabin surveillance and/or video telephone function, such as disclosed in U.S. Pat. Nos. 5,760,962; 5,877,897; 6,690,268 and/or 7,370,983, and/or U.S. Pat. Application Ser. No. 10/538,724, filed Jun. 13, 2005 and published Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, which are hereby incorporated herein by reference in their entireties, a traffic sign recognition system, a system for determining a distance to a leading or trailing vehicle or object, such as a system utilizing the principles disclosed in U.S. Pat. Nos. 6,396,397 and/or 7,123,168, which are hereby incorporated herein by reference in their entireties, and/or the like. 
     Optionally, the circuit board or chip may include circuitry for the imaging array sensor and or other electronic accessories or features, such as by utilizing compass-on-a-chip or EC driver-on-a-chip technology and aspects such as described in U.S. Pat. No. 7,255,451 and/or U.S. Pat. No. 7,480,149; and/or U.S. Pat. Applications, Ser. No. 11/226,628, filed Sep. 14, 2005 and published Mar. 23, 2006 as U.S. Publication No. US-2006-0061008, and/or Ser. No. 12/578,732, filed Oct. 14, 2009 and published Apr. 22, 2010 as U.S. Publication No. US-2010-0097469, which are hereby incorporated herein by reference in their entireties. 
     Optionally, the vision system may include a display for displaying images captured by one or more of the imaging sensors for viewing by the driver of the vehicle while the driver is normally operating the vehicle. Optionally, for example, the vision system may include a video display device disposed at or in the interior rearview mirror assembly of the vehicle, such as by utilizing aspects of the video mirror display systems described in U.S. Pat. No. 6,690,268; 7,370,983; 7,329,013; 7,308,341; 7,289,037; 7,249,860; 7,004,593; 4,546,551; 5,699,044; 4,953,305; 5,576,687; 5,632,092; 5,677,851; 5,708,410; 5,737,226; 5,802,727; 5,878,370; 6,087,953; 6,173,508; 6,222,460; 6,513,252; 5,530,240; 6,329,925; 7,855,755; 7,626,749; 7,581,859; 7,446,650; 7,446,924; 7,370,983; 7,338,177; 7,274,501; 7,255,451; 7,195,381; 7,184,190; 5,668,663; 5,724,187; 7,338,177; 5,910,854; 6,420,036 and/or 6,642,851, and/or European patent application, published Oct. 11, 2000 under Publication No. EP 0 1043566, and/or PCT Application No. PCT/US2011/056295, filed Oct. 14, 2011, and/or U.S. Pat. Applications, Ser. No. 11/226,628, filed Sep. 14, 2005 and published Mar. 23, 2006 as U.S. Publication No. US-2006-0061008; and/or Ser. No. 10/538,724, filed Jun. 13, 2005 and published Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, and/or U.S. Provisional Applications, Ser. No. 61/466,138, filed Mar. 22, 2011; Ser. No. 61/452,816, filed Mar. 15, 2011; and Ser. No. 61/426,328, filed Dec. 22, 2010, which are hereby incorporated herein by reference in their entireties. 
     Optionally, the display or displays and any associated user inputs may be associated with various accessories or systems, such as, for example, a tire pressure monitoring system or a passenger air bag status or a garage door opening system or a telematics system or any other accessory or system of the mirror assembly or of the vehicle or of an accessory module or console of the vehicle, such as an accessory module or console of the types described in U.S. Pat. Nos. 7,289,037; 6,877,888; 6,824,281 ; 6,690,268; 6,672,744; 6,386,742 and 6,124,886, and/or U.S. Pat. Application Ser. No. 10/538,724, filed Jun. 13, 2005 and published Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, which are hereby incorporated herein by reference in their entireties. 
     While the above description constitutes a plurality of embodiments of the present invention, it will be appreciated that the present invention is susceptible to further modification and change without departing from the fair meaning of the accompanying claims.