Abstract:
According to one aspect of the present invention, there is provided a camera system including a motion estimator estimating a motion of an image taken by the camera system, and; a controller controlling, based on the estimation, an update frequency of a predetermined parameter and/or an amount of adjustment of the predetermined parameter per update cycle.

Description:
FIELD OF THE INVENTION 
     This invention relates to camera systems or image processing systems. 
     BACKGROUND OF THE INVENTION 
     Camera devices are controlling various parameters relating to their behavior during their operation. For example, during video recording or previewing for taking a still picture, the camera devices continuously measure brightness or color balance of the taken images and adjust the exposure time or white balance. 
     It is beneficial if such a control mechanism can react quickly on changing conditions. For example when a user moves the camera from a bright window view to a much darker indoor view, the exposure time should be made longer in order to ensure that some amount of details can still be captured. 
     On the other hand, there are cases where the quick adjustment makes the user uncomfortable. For example when recording a video clip, parameters like exposure time of successive image frames should not vary too much. Otherwise the brightness of images may change back and forth between lighter and darker in a short period. The result may be that the recorded video clip appears to comprise a plurality of different video clips made under different lighting conditions. In circumstances where e.g. sudden glimpses of sunlight are included in the view of steadily hold camera, too hasty changes in brightness parameter may further result in pumping effect, that is, brightness continuously changes between darker and lighter in clearly noticeable steps and never settling down. 
     SUMMARY OF THE INVENTION 
     On this background, the present invention intends to provide an intelligent control architecture which can understand well when it is preferable to react quickly to changes in conditions and when it is better to react more slowly. 
     According to one aspect of the present invention, there is provided a camera system comprising: a motion estimator estimating a motion of an image taken by the camera system, and; a controller controlling, based on the estimation, an update frequency of a predetermined parameter and/or an amount of adjustment of the predetermined parameter per update cycle. 
     Accordingly, the update frequency (or rate) and/or the amount of adjustment can be changed by the motion of the scene to be taken. Therefore the adjustment rate and/or amount of adjustment can be optimized for various situations. The user can obtain an appropriate control effect on photography or video which suits for the motion of scene to be taken. Said parameter can be related with one or more of an amount of exposure, an amount of amplifying, white balance, or any other operations of the camera system. 
     In one preferred embodiment, said motion estimator is arranged to divide a shooting area logically into sections and to estimate a motion of an image in each of the sections, and; said controller is arranged to perform said controlling by taking into account results of said estimations of 2 or more of said sections. 
     In this embodiment, said camera system can perform the controlling by taking into account a structure of motions in a scene to be taken. Therefore further appropriate and intelligent control can be realized. 
     The motion estimation can be performed from several successive image frames. However, in one embodiment, said camera system may utilize a motion sensor. With this mind, according to another aspect of the present invention, there is provided a camera system comprising a motion sensor for detecting a motion of the camera system and a controller controlling a frequency of adjusting a predetermined parameter and/or an amount of adjustment of the predetermined parameter per update cycle by taking into account an output signal of the motion sensor. 
     According to further aspect of the present invention, there is provided an electronic circuit for controlling a camera module taking a image data electronically and for processing an output signal of the camera module, the electronic circuit being arranged: to estimate a motion of an image taken by the camera module, and; to change, based on a estimated motion, one or more of a frequency of adjusting a control parameter used for controlling the camera module, an amount of adjustment of the control parameter per update cycle, a frequency of adjusting a processing parameter used for processing the output signal, and an amount of adjustment of the processing parameter per update cycle. 
     According to still further aspect of the present invention, there is provided an image processing unit for controlling a camera module taking a image data electronically and for processing an output signal of the camera module, the image processing unit comprising a processor and a program, and the program being arranged to instruct the processor: to estimate a motion of an image taken by the camera module, and; to change, based on a estimated motion, one or more of a rate of adjusting a control parameter used for controlling the camera module, an amount of adjustment of the control parameter per update cycle, a rate of adjusting a processing parameter used for processing the output signal, and an amount of adjustment of the processing parameter per update cycle. 
     The control parameter may be related with an exposure time, an amount of diaphragming if the camera module comprises a diaphragm, an amount of amplifying a signal from an image sensor, or other operations of the camera module. The processing parameter may be related with a white balance. 
     Above-disclosed electronic circuits can be produced as a semiconductor chip and can be sold in the market. Also above-disclosed electronic circuits can be implemented in a camera device, e.g. a handportable digital camera or a handportable cellular phone having a camera. 
     The present invention includes any combinations of matters described in this specification. Further features or advantages will be described herein below by using an exemplary figures and embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described by way of example only and with reference to accompanying drawings in which: 
         FIG. 1  is a schematic diagram of a camera system  1  according to a preferred embodiment of the present invention. 
         FIG. 2  is a schematic illustration that a frame is divided into macroblocks 
         FIG. 3  illustrates an embodiment of the camera system  1 . 
         FIG. 4  illustrates another embodiment of the camera system  1 . 
         FIG. 5  illustrates a circuit package containing a DSP and a memory. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a schematic diagram of a camera system  1  according to a preferred embodiment of the present invention. The camera system comprises a lens  11 , a diaphragm  13 , a CCD or CMOS sensor  15 , an analog amplifier  17 , an A/D converter  19 , a white balance amplifier  21 , a lighting condition analyzer  23 , a controller  25 , a CFA interpolator  27 , a thumbnail creator  29 , a display  31 , data compressor  33 , a memory  35 . The lens  11  concentrates and focuses incident light on the CCD sensor  15 . The sensor  15  converts the incident light to an electric signal. The sensor  15  also comprises an electric shutter, and data taking (shooting) will be performed only the electric shutter is opened. The shutter speed is variable and controlled by the controller  25 . The analog amplifier  17  amplifies the output signal of the CCD sensor  15 . The magnitude (amount) of amplifying is variable, and controlled by the controller  25 . A/D converter  19  converts the amplified signal to a digital-format data. This digital data may be called as a raw data, and have a RGB or CMY Bayer format, which will be used for constructing a photographic or a video data. 
     The white balance amplifier  21  adjusts a white balance of the raw data, i.e. digitally amplifying or discriminating one or more of color components of the raw data so that the raw data can express a white object as white. The amount of adjustment is directly controlled by the controller  25  based on an analysis of the lighting condition analyzer  23 . The lighting condition analyzer  23  estimates a lighting condition of a view taken by the sensor  15  from the raw data which is not white-balanced. The lighting condition analyzer  23  also measures brightness (or intensity) of the raw data which is not white-balanced. Based on the brightness measurement, the controller changes one or more of an amount of diaphragming of the diaphragm  13 , a shutter speed of the sensor  15 , and a magnitude (amount) of amplifying by the amplifier  17 . 
     The CFA interpolator  27  constructs a photographic image data from the white-balanced raw data by applying a CFA (Color Filter Array) interpolation. This image data can be directly replayed by many of existing digital systems, i.e. personal computers, mobile phones or digital cameras. In an embodiment, the video recording, the CFA interpolator  27  may not be needed, especially when the sensor comprises the same number of pixels for each color components. Also the CFA interpolator  27  may not be used for video recordings, so as to increase the processing speed. 
     The thumbnail creator  29  creates a thumbnail image from the image data constructed by the CFA interpolator  27 . The thumbnail images will be displayed on the display  31 , for the purpose of previewing or confirming the taken still/video images. The data compressor  33  compresses the image data, i.e. by JPEG, JPEG2000, Motion JPEG, or MPEG. The compressed data is stored in the memory  35 . It is preferable that the compressed image data is stored together with its thumbnail image. 
     The camera system  1  also comprises a motion analyzer  37 . The motion analyzer analyzes the raw data to estimate a motion of the image taken by the CCD sensor. The camera system  1  can use any of existing method for motion estimation as long as requirements (i.e. size, price, speed, power consumption) are satisfied. In this embodiment the motion estimation is carried out by comparing successive image frames. A frame means a total area of a still picture or a single picture in a series of video data. The motion analyzer  37  divides a frame logically into a plurality of sections (smaller areas), and performs the motion estimation for each of the sections. This smaller area (section) is called a macroblock. The motion analyzer  37  can estimate the amount (speed) of the motion. It is possible to arrange the motion analyzer  37  to estimate the direction of the motion too. 
       FIG. 2  schematically illustrates that a frame is divided into macroblocks (sections) and the motions are estimated for each macroblocks. A frame  50  schematically represents a total area of a still picture or a single picture in a series of video data. The motion analyzer  37  divides the frame  50  logically into 4 macroblocks—A, B, C, and D, and estimates the motions for each macroblocks ( FIG. 2   a ). In one case, it may be estimated that all macroblocks have almost same amount of motion, as illustrated in  FIG. 2   b . This case would happen when a user is moving the camera system  1 . In the other cases, it may be estimated that the Macroblock D is moving a lot, however, macroblock A, B, C are not moving ( FIG. 2   c ) or are moving but only a little ( FIG. 2   d ). Those cases may happen when the frame  50  contains a moving object, i.e. a car, a train, a running man, . . . , on a stable background. 
     Please note that the  FIG. 2   a - d  is just a schematic example. For the real products the number of macroblocks may be an order of ten or hundred. 
     When the estimated motion speeds are small or zero for all macroblocks, as like the example of  FIG. 2   a , then the controller  25  changes one or more control parameters to reduce one or more of a rate of adjusting the diaphragm  13 , the shutter speed of the CCD or CMOS sensor  15 , the magnitude of amplifying of the amplifier  17 , and white balance in the white balance amplifier  21 . This is because the lighting condition may not be changed dramatically; those adjustments need not to be performed so frequently. Then the user does not need be annoyed by a quick change of colors of the images caused by the quick change of the control parameters, which are presented in the display  31  or stored in the memory  35 . Also this feature may be able to save a power consumption used for said adjustments. 
     The control parameter(s) may be parameter(s) for controlling one or more of adjustable amounts at one time for the diaphragm  13 , the shutter speed of the CCD sensor  15 , the magnitude of amplifying of the amplifier  17 , and white balance in the white balance amplifier  21 . By reducing such adjustable amounts the quick change of colors or images may also be avoided. 
     When the estimated motion speeds are large for all macroblocks, as like the case illustrated in  FIG. 2   b , then the controller  25  changes one or more said control parameters to increase the rate of adjusting one or more of the diaphragm  13 , the shutter speed of the CCD sensor  15 , the amplifier  17 , and the white balance amplifier  21 . In such case, the user may be taking a picture or video with moving the camera system  1 , so the lighting condition can be changed largely, i.e. from indoor to outdoor. By increasing the adjustment rate the camera system  1  can provide a user with images taken with the appropriate exposure, amplification and/or white balancing even for the case that the scene to be taken is changing quickly. 
     In case the motion analyzer  37  estimates that the large motions exist only in a part of the frame, as illustrated in  FIG. 2   c  or  FIG. 2   d , the controller  25  does not increase the adjustment rate at all, or does not increase so much compared with the case of  FIG. 2   b . This is because, in such cases the scene to be taken may contain a moving object only in a part of the frame, and remaining parts may be stable. And the lighting condition may not change dramatically for such scenes. So the system may not need to adjust the exposure, brightness or white balance so frequently. 
     The camera system  1  can comprise a motion sensor  39  for detecting a motion of the camera system  1  itself, and the controller  25  can be arranged to perform the controlling with taking account of the signal of the motion sensor. 
       FIG. 3  illustrates an example embodiment of the camera system  1 . In this embodiment, the camera system  1  can be an imaging phone, that is, a handportable cellular phone comprising a camera and being able to take still pictures and videos. The imaging phone  100  comprises a camera module  102  and a phone module  104 , and those modules are house in a common housing. The camera module  102  comprises a lens  111 , a diaphragm  113 , a CCD or CMOS sensor  115 , an analog amplifier  117 , an A/D converter  119 . These units correspond to the lens  11 , the diaphragm  13 , the CCD sensor  15 , the analog amplifier  17 , the A/D converter  19  of the camera system  1  respectively, and contain the same functionality with them. 
     The phone module  104  comprises a user interface  131  containing a display and a keypad, a memory  135 , a motion sensor  139 , CPU  141 , DSP  143 , and communication section  145  containing baseband processing, RF processing and antennas. The display of the UI  131 , the memory  135  and the motion sensor  139  correspond to the display  11 , the memory  35 , the motion sensor  39  and contain the same functionality with them. 
     The memory stores a program for the CPU  141 . The CPU  141  controls the whole of the phone module  104  in accordance with the instructions of the program. The memory stores another program which is used for the DSP  143 . This program instructs the DSP  143  to perform the functionalities of the white balance amplifier  21 , the lighting condition analyzer  23 , the controller  25 , the CFA interpolator  27 , the thumbnail creator  29 , the compressor  33 , and the motion analyzer  37 . 
     Referring to  FIG. 5 , the DSP  143  can be sold independently as a package  300  containing the DSP  143 , a memory and said program for the DSP  143 . 
       FIG. 4  illustrates another example embodiment of the camera system  1 . In this embodiment, the camera system  1  is also implemented as an imaging phone. As the imaging phone  100  of the previous example, the imaging phone  200  also comprises a camera module  202  and a phone module  204 . However, the camera module  202  has more functions than the camera module  101 . 
     The camera module  202  comprises a lens  211 , a diaphragm  213 , a CCD and/or CMOS sensor  215 , an analog amplifier  217 , an A/D converter  219 , a white balance amplifier  221 , a lighting condition analyzer  223 , a controller  225 , a CFA interpolator  227 , a thumbnail creator  229 , and a motion analyzer  237 . These units correspond to the lens  11 , the diaphragm  13 , the sensor  15 , the analog amplifier  17 , the A/D converter  19 , the white balance amplifier  21 , the lighting condition analyzer  23 , the controller  25 , the CFA interpolator  27 , the thumbnail creator  29 , and the motion analyzer  37  of the camera system  1  respectively, and contain the same functionality with them. However, in contrast with the embodiment explained with  FIG. 3 , the white balance amplifier  221 , the lighting condition analyzer  223 , the controller  225 , the CFA interpolator  227 , the thumbnail creator  229 , and the motion analyzer  237  are implemented by hardware circuits. That is, those functionalities do not use software processing, or use very little software processing compared with the embodiment using a CPU or a DSP for realizing those functionalities. The hardware circuit containing one or more of the white balance amplifier  221 , the lighting condition analyzer  223 , the controller  225 , the CFA interpolator  227 , the thumbnail creator  229 , and the motion analyzer  237  can be integrated in a chip, and sold as an independent product. 
     The phone module  204  comprises a user interface  231 , a memory  235 , CPU  241 , a communication section  245 . Those units correspond to the user interface  131 , the memory  135 , the CPU  141 , and the communication section  145 , and have the same functionalities with them. The CPU  241  controls the whole of the phone module  204  in accordance with the instructions of the program. The CPU  241  can also changes the behavior of the controlling function of the controller  225  in accordance with the instructions of the program stored the memory  235  or with the instructions of the user inputted through the user interface  231 . 
     Please note that various modifications may be made without departing from the scope of the present invention. For example, what the controller  25  controls are not limited to described examples, but can be many other things, e.g. a shutter speed of a mechanical shutter if the camera system  1  comprises a mechanical shutter. 
     Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature of combination of features hereinbefore referred to and/or shown in the drawings whether of not particular emphasis has been placed thereon.