Abstract:
Image pickup system having an image pickup device including an image pickup element for picking up the image of an object and outputting image data, a compression encoding circuit for effecting compression encoding of the image data, a wireless transmission circuit for modulating the compression encoded image data and transmitting the data to a wireless transmission channel, and a first connector adapted to be electrically and mechanically connected, in a detachable manner, to a display device for displaying the image picked-up by the image pickup element and to transmit the image data from the image pickup element. The system also includes a display device including a wireless reception circuit for receiving the transmitted image data from the wireless transmission channel. The display device selectively receives first or second image data and processes the received image data to output an image signal of a predetermined format.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a divisional application of application Ser. No. 08/841,564, filed Apr. 30, 1997, which issued as U.S. Pat. No. 6,148,141 on Nov. 14, 2000. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an image pickup device adapted for use in a camcorder (camera-integrated video cassette recorder), a display device for displaying the picked-up image, and an image pickup system consisting of the image pickup device and the display device. 
   2. Related Background Art 
   In the conventional camcorder (camera-integrated video cassette recorder), an image pickup unit and an image display unit including a monitor and a VCR (video cassette recorder) are mutually inseparably integrated. For this reason, in case of image pickup by placing such camcorder in a place unreachable by the photographer, the image to be picked-up cannot be confirmed on the monitor. 
   For avoiding such drawback, there has been known a camcorder in which an image pickup unit and an image display unit are separated as shown in  FIG. 14 . 
   In  FIG. 14 , there are shown an image pickup unit  10 , an image display unit  11 , a lens  1  for forming the image of an object, an image pickup device  2  for converting the formed image of the object into an image signal, a CDS/AGC circuit  3  for effecting sample holding of the image signal, thereby obtaining an appropriate signal level, a digital signal processing unit  4  for effecting A/D conversion on the image signal from the CDS/AGC circuit  3  and effecting digital signal processing, an NTSC encoder  5  for converting the digital image signal from the digital signal processing circuit  4  into an NTSC image signal, a cable  6  connecting the image pickup unit  10  and the image display unit  11 , a monitor  7  for displaying the NTSC image signal supplied from the image pickup unit  10  or reproduced from a recording medium to be explained later, a recording/reproducing unit  8  for recording the NTSC image signal from the image pickup unit  10  on a recording medium or reproducing such signal from the recording medium, and attaching/detaching means  9   a ,  9   b  for mechanically attaching or detaching the image pickup unit  10  and the image display unit  11 . 
   In such configuration, the image pickup operation by the image pickup unit  10  can be made while the image display unit  11  is separated, and both can be united in use, if necessary, by the attaching/detaching means  9   a ,  9   b.    
   In such conventional camcorder, however, a cable is extended from the image pickup unit and hinders the freedom of image pickup operation. 
   SUMMARY OF THE INVENTION 
   In consideration of the foregoing, an object of the present invention is to separate the image pickup unit and the image display unit in mutually separable and unitable manner, thereby increasing the freedom in the image pickup operation. 
   Another object of the present invention is to avoid increase of the electric power consumption in attaining the above-mentioned object. 
   Still another object of the present invention is to achieve efficient image transmission from the image pickup unit to the image display unit. 
   The above-mentioned objects can be attained, according to the present invention, by an image pickup device comprising image pickup means for picking up the image of an object and outputting image data, first compression encoding means for compression encoding of the image data, wireless transmission means for modulating thus compression encoded image data for transmission to a wireless transmission channel, and connection means adapted to be mechanically and electrically connected in detachable manner to a display device for displaying the image picked-up by the image pickup device and to transmit the above-mentioned image data from the image pickup means. 
   Also according to the present invention, there is provided a display device comprising wireless reception means for receiving and demodulating the compression encoded and modulated image data from the wireless transmission channel, first expansion means for expanding thus demodulated image data thereby obtaining first image data, connection means adapted to be mechanically and electrically connected in detachable manner to the image taking device and to receive second image data from the image pickup device, signal processing means for selectively receiving the first and second image data and processing thus received image data to output an image signal of a predetermined system, and display means for displaying the image signal of the above-mentioned predetermined system. 
   Also according to the present invention, there is provided an image pickup system comprising an image pickup device including image taking means for taking the image of an object and outputting image data, compression encoding means for compression encoding of the image data, wireless transmission means for modulating thus compression encoded image data for transmission to wireless transmission channel, and first connection means adapted to be mechanically and electrically connected in detachable manner to a display device for displaying the image picked-up by the image pickup device and to transmit the above-mentioned image data from the image pickup means; and a display device including wireless reception means for receiving and demodulating the transmitted image data from the wireless transmission channel, expansion means for expanding thus demodulated image data thereby obtaining first image data, second connection means adapted to be mechanically and electrically connected in detachable manner to the first connection means and to receive second image data from the image pickup device, signal processing means for selectively receiving the first and second image data and processing thus received image data to output an image signal of a predetermined system, and display means for displaying the image signal of the above-mentioned predetermined system. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing an image pickup unit in a first embodiment of the present invention; 
       FIG. 2  is a block diagram showing an image display unit in the first embodiment; 
       FIG. 3  is a block diagram showing an image taking unit in a second, third or fifth embodiment; 
       FIG. 4  is a block diagram showing an image display unit in the second embodiment; 
       FIG. 5  is a block diagram showing a JPEG image compression circuit; 
       FIG. 6  is a block diagram showing a JPEG image expansion circuit; 
       FIG. 7  is a block diagram showing a DV image compression circuit: 
       FIG. 8  is a block diagram showing an image display unit in the third embodiment; 
       FIG. 9  is a block diagram showing an image taking unit in a fourth embodiment; 
       FIG. 10  is a block diagram showing an image display unit in the fourth embodiment; 
       FIG. 11  is a block diagram of an MPEG image compression circuit; 
       FIG. 12  is a block diagram of an MPEG image expansion circuit; 
       FIG. 13  is a block diagram showing an image display unit in the fifth embodiment; and 
       FIG. 14  is a block diagram of a conventional camcorder. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following there will be explained first to fifth embodiments in which the present invention is applied to a camcorder, with reference to the attached drawings. In  FIGS. 1 to 13 , mutually corresponding components are represented by a same number and will not be explained repeatedly. 
     FIG. 1  is a block diagram of an image pickup unit  100  of a camcorder in a first embodiment of the present invention, and  FIG. 2  is an image display unit  200  of the camcorder. 
   In the image pickup unit  100  shown in  FIG. 1 , there are provided a lens  101  for forming the image of an object, an image pickup device  102  for converting thus formed image into an image signal, a CDS/AGC circuit  103  for effecting sample holding on the image signal thereby providing an appropriate signal level, a digital signal processing circuit  104  for A/D conversion of the image signal from the CDS/AGC circuit  103  and digital signal processing, an image compression circuit  105  for compression encoding of the digital image signal from the digital signal processing circuit  104 , a spectrum diffusion transmission circuit  106  for transmitting the compressed image data from the image compression circuit  105  by spectrum diffusion modulation, and a transmitting antenna  107 . 
   There are also provided a microcomputer  108 , a power source  109 , a power source control unit  110  for on/off control of the power supply to various units according to commands from the microcomputer  108 , a joining detection device  112  for detecting that an image display unit  200  to be explained later is coupled, a signal connection device  113  for connecting the digital signal processing circuit  104  with the image display unit  200  when it is coupled, and an attaching/detaching device  114  including the joining detection device  112  and the signal connection device  113  and adapted to electrically and mechanically connect, in detachable manner, to the image display unit  200 . 
   In the image display unit  200  shown in  FIG. 2 , there are provided a receiving antenna  201 , a spectrum diffusion reception unit  202  for receiving the image data transmitted from the image pickup unit  100  and effecting demodulation to restore the compressed image data, an image expansion unit  203  for expanding the compressed image data to obtain the digital image signal, an NTSC encoder  204  for converting the digital image signal into the NTSC image signal, a recording/reproducing unit  205  for recording and reproducing the NTSC image signal, a recording medium  206 , and a monitor  207  for displaying the NTSC image signal. 
   There are also provided a microcomputer  208 , a power source  209 , a power source control unit  110  for on/off control of the power supply to various unit according to commands from the microcomputer  208 , a joining detection device  211  for detecting that the image display unit  100  is coupled, a signal connection device  212  for connecting the NTSC encoder  204  with the image pickup unit  100  when it is coupled, and an attaching/detaching device  213  including the joining detection device  211  and the signal connection device  212  and adapted to electrically and mechanically connect, in detachable manner, to the image pickup unit  100 . 
   The image compression circuit  105  mentioned above can also be a pixel thinning-out circuit for processing the digital image signal from the digital signal processing circuit  104  in the unit of each pixel and reducing the number of pixels by pixel thinning-out. Also the image expansion circuit  203  mentioned above can also be a pixel interpolation circuit for processing the digital image signal from the spectrum diffusion reception unit  202  in the unit of each pixel to effect interpolation of the pixels. 
   In the above-explained configuration, when the image pickup unit  100  and the image display unit  200  are mutually separated, the image picked-up by the image pickup unit  100  is transmitted by wireless transmission to the image display unit  200  in a distant location and can be monitored and/or recorded and reproduced therein. Consequently the photographer can place the image pickup unit  100  in a distant location, without being concerned with the location of the image display unit  200 , whereby freedom of the image pickup operation can be increased. It is also possible to take out the picked-up image from the signal connection device  113  and send it to an external equipment such as a computer. It is furthermore possible to supply the signal connecting device  212  of the image display unit  200  with the image signal from an external equipment, thereby monitoring and/or recording and reproducing such image signal. 
   In such case, the joining detection devices  112 ,  211  do not detect the coupled state, so that the microcomputers  108 ,  208  supply the power source control units  110 ,  210  with commands to feed electric power to all the units. 
   On the other hand, in case the image pickup unit  100  and the image display unit  200  are integrally coupled by connection through the attaching/detaching devices  114 ,  213 , the joining detection devices  112 ,  211  detects such coupled state, whereby the microcomputers  108 ,  208  supply the power source control units  110 ,  210  with commands to terminal power supply to the spectrum diffusion transmission unit  106 , the spectrum diffusion reception unit  202 , the image compression circuit  105  and the image expansion circuit  203  whereupon the power supply to these circuits is terminated. In this manner the electric power consumption can be reduced in the coupled state. 
   In case the both units are mutually separated, the image signal is transmitted with a reduced data amount obtained by compression, so that it can be transmitted without difficulty even by wireless digital transmission which is limited in the transmission rate. Also the use of the spectrum diffusion modulation allows transmission of the signal of a wide band with a limited electric power. On the other hand, in case the both units are mutually coupled, a high image quality can be obtained since the image signal is transmitted without compression. 
   In the following there will be explained a second embodiment. 
   The present embodiment employs, for the image compression, the JPEG compression method and the DV compression method. The JPEG compression method, capable of achieving a high compression rate for the image data, is suitable for image transmission in the wireless transmission channel limited in the transmission rate. The JPEG compression method is often employed in the personal computers as the image data format. 
   On the other hand, the DV compression method is widely employed in the digital CVR because of very high image quality, though the image data compression rate is not so high. 
     FIG. 3  shows the image pickup unit  100  in the second embodiment, and  FIG. 4  shows the image display unit  200  therein. 
   In the image taking unit  100  shown in  FIG. 3 , there are provided a JPEG image compression circuit  115  for compressing, in the JPEG method, the digital image signal from the digital signal processing circuit  104 , a DV image compression circuit  116  for compressing, in the DV method, the digital image signal from the digital signal processing circuit  104 , a compression method selecting switch  117  for connecting the digital signal processing circuit  104  to the JPEG image compression circuit  115  or the DV image compression circuit  116  according to a command from the microcomputer  108 , and a compression method selecting switch  118  shifted in linkage with the switch  117 , for connecting the signal connecting device  113  to the JPEG image compression circuit  115  or the DV image compression circuit  116 . 
   In the image display unit  200  shown in  FIG. 4 , there are provided a JPEG image expansion circuit  214  for expanding the JPEG compressed image to restore the digital image signal, a DV image compression circuit  215  for compressing, by the DV method, the digital image signal from the JPEG image compression circuit  214 , a DV image expansion circuit  216  for expanding the DV compressed image data from the signal connecting device  212  to restore the digital image signal, a digital recording/reproducing unit  217  for digital recording and reproduction of the DV compressed image data on or from the recording medium  206 , and an image selecting switch  218  for connecting the digital recording/reproducing unit  217  to the DV image compression circuit  215  or the signal connecting device  212  according to the command from the microcomputer  208 . 
   In the above-explained configuration, when the image pickup unit  100  and the image display unit  200  are mutually separated, the joining detection devices  112 ,  211  do not detect the coupled state, so that the microcomputers  108  of the image pickup unit  100  instructs the switch  117  to connect the digital signal processing circuit  104  to the JPEG image compression circuit  115 . Also linked with the switch  117 , the switch  118  connects the signal connecting device  113  to the JPEG image compression circuit  115 . On the other hand, the microcomputer  208  of the image display unit  200  instructs the switch  218  to connect the digital recording/reproducing unit  217  to the DV image compression circuit  215 . 
   In this state, the signal flows along paths of lens  101 →image pickup device  102 →CDS/AGC circuit  103 →digital signal processing circuit  104  switch  117 →JPEG image compression circuit  115 →spectrum diffusion transmission unit  106 →transmitting antenna  107 →receiving antenna  201 →spectrum diffusion reception unit  202 →JPEG image expansion circuit  214  DV image compression circuit  215 →switch  218 →digital recording/reproducing unit  217 →recording medium  206 , and of JPEG image expansion circuit  214 →NTSC encoder  204 →monitor  207 . 
   The JPEG compressed signal is released from the JPEG image compression circuit  115  through the switch  118  to the signal connecting device  113 , it can be transmitted for example to the computer. Also the external DV compressed signal can be supplied to the image display unit  200  through the signal connecting device  212 . 
   At the reproducing operation, the microcomputer  208  instructs the switch  218  to connect the digital recording/reproducing unit  217  to the DV image expansion circuit  216 . In this state the signal flows along a path of recording medium  206 →digital recording/reproducing unit  217 →switch  218 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   On the other hand, when the image pickup unit  100  and the image display unit  200  are integrally coupled, the joining detection devices  112 ,  211  detect the coupled state. The microcomputer  108  of the image pickup unit  100  instructs the switch  117  to connect the digital signal processing circuit  104  to the DV image compression circuit  116 . Linked with the switch  117 , the switch  118  connects the signal connecting device  113  to the DV image compression circuit  116 . On the other hand, the microcomputer  208  of the image display unit  200  instructs the switch image selecting switch  218  to connect the digital recording/reproducing unit  217  to the signal connecting device  212 . 
   In this state, the signal flows along paths of lens  101 →image pickup device  102 →CDS/AGC circuit  103 →digital signal processing circuit  104 →switch  117 →DV image compression circuit  116 →switch  118 →signal connecting device  113 →signal connecting device  212 →switch  218 →digital recording/reproducing unit  217 →recording medium  206 , and of signal connecting device  212 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   In the reproducing operation, the signal flows along a path of recording medium  206 →digital recording/reproducing unit  217 →switch  218 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   In the present embodiment explained above, when the image pickup unit  100  and the image display unit  200  are separated, the JPEG method is selected for image compression, whereby the wireless transmission can be achieved in efficient manner. 
   When the image taking unit  100  and the image display unit  200  are integrally coupled, the DV method is selected for image compression, thereby achieving digital image recording of high image quality. 
     FIG. 5  is a block diagram showing the configuration of the JPEG image compression circuit  115  in  FIG. 3 , wherein provided are a raster-block conversion unit  301 , a DCT (discrete cosine transformation) unit  302 , a quantization unit  303 , a Huffman encoding unit  304 , a quantization table  305  to be used in the quantization unit  303 , and a Huffman table  306  to be used in the Huffman encoding unit  304 . 
   In the JPEG image compression circuit  115  of the above-explained configuration, the input digital image signal consisting of luminance/color difference signals of raster format is divided by the raster block conversion unit  301  into blocks of 8×8 pixels, each represented by an 8×8 square matrix. Then the DCT unit  302  executes a DCT process (discrete cosine transformation) on the 8×8 matrix data. The transformed data, called DCT coefficients, are also 8×8 matrix data of which terms at the upper left part represent the magnitudes of the low frequency components of the original image while those at the lower right part represent the magnitudes of the high frequency components of the original image. 
   Then the quantization unit  303  executes divisions of the data in the above-mentioned matrix respectively, utilizing a coefficient table called the quantization table  305 . The quantization table  305  is weighted in the high frequency components with respect to the low frequency components, so that the results of the divisions constitute matrix data of which values decrease progressively toward the higher frequency. Subsequently there is executed quantization to reduce the values less than a predetermined value to zero, whereby most values in the lower right part of the matrix data become zero. 
   Then the above-mentioned matrix data are arranged as a data train in an order called zigzag scan, and are subjected to a transformation called Huffman encoding in the Huffman encoding unit  304 . This transformation replaces a redundant portion of the data (a data portion where a same value appears in continuation). In the above-mentioned data train, the portion with value 0 in continuation is significantly shortened, whereby the amount of the image data is compressed. 
     FIG. 6  is a block diagram showing the configuration of the JPEG image expansion circuit  214  in  FIG. 4 , wherein are provided a Huffman decoding unit  401 , a Huffman table  402  to be used in the Huffman decoding unit  401 , an inverse quantization unit  403 , a quantization table  404  to be used in the inverse quantization unit  403 , an inverse DCT unit  405 , and a block-raster conversion unit  406 . 
   In the JPEG image expansion circuit  214  of the above-explained configuration, the input JPEG compressed image signal is subjected to Huffman decoding in the Huffman decoding unit  401  to provide the original data train. This data train is returned to the matrix data, which are subjected to multiplications in the inverse quantization unit  403  based on the quantization table  404 . The matrix data obtained in this state contain a larger number of 0 in the higher frequency components, in comparison with the aforementioned DCT coefficients. Then the inverse DCT unit  405  executes an inverse DCT and the block-raster conversion unit  406  rearranges the blocks in the original order, thereby providing the expanded digital image. 
     FIG. 7  shows the configuration of the DV image compression circuit  215  in  FIG. 4 , wherein are provided a block division shuffling circuit  501 , a DCT operation weighing circuit  502 , a rearrangement circuit  503 , an adaptive quantization circuit  504 , a variable length encoding circuit  505 , a deshuffling circuit  506 , a motion detection circuit  507  and a code amount estimation circuit  508 . 
   In the configuration explained above, the data with converted transmission rate are converted, in the block division shuffling circuit  501 , into blocks of 8×8 pixels each, in each of the luminance signal and the two color difference signals, and a macroblock is constituted by six blocks consisting of four Y signal blocks and two color difference signal blocks. The divided data are then subjected to a rearrangement of the positions on the image in order to average the amount of information constituting the portion of a fixed length, and are subjected to the DCT operation (discrete cosine transformation) in the DCT operation weighing circuit  502 . In this operation, an image with a large amount of motion is processed within a frame, and the motion detection circuit  507  is provided for this purpose. After the DCT operation, the data are weighted, rearranged by the rearrangement circuit  503 , and quantized by the adaptive quantization circuit  504 . The quantized data are subjected to variable length coding (VLC) in the variable length encoding circuit  505 , in such a manner that the amount of codes after variable length encoding becomes constant for every macroblock, by estimating the amount of codes at the quantization. The encoded data are outputted after being returned to the original position in the image. The output digital signal is given an error correction code, and deshuffled by the deshuffling circuit  506 , whereby compressed data are outputted. 
   In the following there will be explained a third embodiment. 
   In this embodiment, the image pickup unit  100  is identical, in configuration, with that shown in  FIG. 3  in the second embodiment, but the image display unit  200  has a configuration shown in  FIG. 8 , which is different in the arrangement of the various units from that shown in  FIG. 4 . 
   In the above-mentioned configuration, when the image pickup unit  100  and the image display unit  200  are mutually separated, the signal flows along paths of lens  101 →image pickup device  102  →CDS/AGC circuit  103 →digital signal processing circuit  104 →switch  117 →JPEG image compression circuit  115 →spectrum diffusion transmission unit  106 →transmitting antenna  107 →receiving antenna  201 →spectrum diffusion reception unit  202 →JPEG image expansion circuit  214 →DV image compression circuit  215 →switch  218 →digital recording/reproducing unit  217 →recording medium  206 →and of switch  218 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   At the reproducing operation, the signal flows along a path of recording medium  206 →digital recording/reproducing unit  217 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   On the other hand, when the image pickup unit  100  and the image display unit  200  are integrally coupled, the signal flows along paths of lens  101 →image pickup device  102 →CDS/AGC circuit  103 →digital signal processing circuit  104 →switch  117  DV image compression circuit  116 →switch  118 →signal connecting device  113 →signal connecting device  212 →switch  218 →digital recording/reproducing unit  217 →recording medium  206 , and of switch  218 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   At the reproducing operation, the signal flows along a path of recording medium  206 →digital recording/reproducing unit  217 →DV image expansion circuit  216 →NTSC encoder  204 →monitor  207 . 
   In the following there will be explained a fourth embodiment. 
   This embodiment employs MPEG compression method instead of the JPEG compression method in the second and third embodiments. Consequently the image pickup unit  100  is provided, as shown in  FIG. 9 , with an MPEG image compression circuit  119 , and the image display unit  200  is provided, as shown in  FIG. 10 , with an MPEG image expansion circuit  219 . The remaining parts in  FIG. 9  correspond to those in  FIG. 3 , and the remaining parts in  FIG. 10  correspond to those in  FIG. 4 . Also the signal paths in the recording and reproducing operations are similar to those in the configurations shown in  FIGS. 3 and 4 . 
     FIG. 11  is a block diagram showing the configuration of the MPEG image compression circuit  119 , wherein provided are an information source encoder  801  for compressing the amount of input information by effecting the aforementioned DCT, quantization etc., a video signal multiplexer  802  for converting thus compressed data into data based on the MPEG format, a transmission buffer  803  for transmitting the data of the above-mentioned format at a predetermined data rate, and an encoding controller  804  for increasing or decreasing the amount of the generated information. 
     FIG. 12  is a block diagram showing the configuration of the MPEG image expansion circuit  219 , wherein provided are a reception buffer  901  for securing a decoding process time for the received data, a video signal demultiplexer  902  for extracting the compressed data from the received format data, and an information source decoder  903  for restoring the original image signal by inverse quantization, inverse DCT etc. 
   The MPEG compression method is featured by executing, in the information source encoder  801 , an anticipated encoding of representing the object image in the form of the difference from a past image or the difference from an anticipated image estimated from the past image, in addition to the aforementioned DCT and quantization, and can provide a higher compression rate, in comparison with the JPEG method which provides a series of compressed images each completed within an image frame. 
   In the following there will be explained a fifth embodiment. 
   This embodiment employs the MPEG compression method in the third embodiment shown in  FIG. 8 , instead of the JPEG compression method therein. Consequently the image display unit  200  is provided with an MPEG image expansion circuit  219  but is same in other parts as the configuration shown in  FIG. 8 . The image pickup unit  100  is same as that shown in  FIG. 9 . Also the signal flow paths in the recording and reproducing operations are same as those in the third embodiment. 
   In the foregoing embodiments, when the image pickup device and the image display device are mutually separated, the image pickup device can send the compression encoded image data to the image display device by wireless transmission, without the connecting cable and with a reduced data amount, whereby the freedom of the image pickup operation can be increased. Also when the image pickup device and the image display device are integrally coupled through the connection means, the image pickup device can directly transmit the image data through the connection means. 
   Also satisfactory image transmission can be achieved by selecting two suitable compression methods. In particular, the JPEG compression method enables efficient transmission when the image pickup device and the image display device are mutually separated, and the DV compression method allows to improve the image quality when the devices are integrally coupled. 
   Also the electric power consumption can be saved by interrupting the power supply to the unnecessary circuits, when the devices are integrally coupled. 
   It is also rendered possible, in the separated state of the devices, to send the image data to an external equipment from the connection means of the image pickup device, and to supply the connection means of the image display device with external image data and to display such image data. 
   Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.