with reference to fig3 a , a document imaging system 300 is fully integrated with a personal computing device , briefly referred to as a personal computer ( pc ) 301 in a fashion that the software programming unit ( spu ) 303 executed within the pc controls and implements the primary functions of the document imaging system 300 in software instruction code , while communicating with a miniaturized digital image sensing unit ( disu ) 302 , in full duplex fashion . the spu 303 thus becomes the master or core unit , and the disu 302 becomes a slave or auxiliary unit of the document imaging system . this ensures that functionality of the system can be made available to users in far more interactive and friendly ways comparing small control buttons on traditional electronic devices , while streamlining the configuration of the disu 302 to an optimal level . the disu 302 communicates with the spu 303 residing in a pc 301 via a high speed digital connection ( named as usb for illustration purpose ) 304 , such as usb 2 . 0 , usb 3 . 0 , firewire / ieee 1934 400 or ieee 1934 800 . the spu receives electric power from the pc 301 via the same digital connection , for the necessary imaging sensing processing functionality , without mandatorily requiring an external power source . the highly compact document imaging system 300 includes a built - in illuminating light source , with its power source also primarily supplied by the pc 301 through the same usb connection 304 , while an external powerful source unit is only optional . the disu 302 is supported by a highly compact camera stand 305 with a folding suspension arm 306 that houses the disu 302 along with an image processing electronic circuitry board 314 ( shown in fig3 b ) and supported by a weighted small profile base 308 . the document imaging system could also be optionally augmented by including a flexible positioning mat 307 , which has pre - defined markings to assist users in positioning the camera stand 305 , and the paper document to be “ scanned ” or visualized . with reference to fig3 b , the disu 302 comprises a miniaturized optical lens 316 along with a digital image sensor ( not separately shown ), and has a resolution of minimum of three mega - pixels and can reach 20 to 30 mega - pixel range resolutions . the optical lens 316 and the accompanying electronic components are capable of capturing real - time video at approximately 30 frames per second with high definition ( hd ) resolution , while being able to capture still pictures of the objects under the camera lens at the same time . the optical lens 316 has limited zoom range or can be a fixed focal lens . the depth of field of the disu 302 lens however has a wide range of above 100 cm , ensuring objects appearing under the facing - down disu 302 appear focused and sharp even when the disu is substantially far away . such a small imaging unit is as light as less than 1 oz in weight . hence , the need for a large volume housing unit is eliminated . the disu 302 can be easily encased in a highly compact space . for example , the embodiment of the disu housing as shown in fig3 a - 3 c can be as small as only 2 . 5 cm × 5 cm × 20 cm and in some embodiments even smaller . the entire housing assembly including the electronic circuitry is encased in the folding suspension arm 306 . for example , the embodiment shown in fig3 a - 3 d is no more than 20 cm in length . in one possible embodiment of the present system , the upright portion of the stand has two tube shaped parts : top part 309 and bottom part 310 with the top part 309 being inside the bottom part 310 . the top part 309 can move up and down so that when it is moved down , the total height of the stand can be reduced , hence the entire device 300 becomes smaller in size and easier to transport . the telescoping relationship is shown in fig3 d . the presence of groove in combination with an internal tooth ( not shown ), groove 318 , and actuating lock 320 help a presenter raise and lower the top part 309 without having to substantially readjust the suspension arm 306 to reacquire the target . the lightweight disu encasing further makes it possible for the base of the camera stand to be free standing instead of fastened to any desk surface , while maintaining stability only by including certain heavy matter like cast - iron weight matter . therefore , the complete external apparatus encasing the disu 302 is highly compact , lightweight , free standing with a folding suspension arm , which makes the apparatus highly portable . displaying real - time video preview with zooming - in and zooming - out is achieved by the spu 303 &# 39 ; s instruction to the disu 302 to capture and transmit a continuous stream of frames of images of a minimum of 2 mega - pixel resolution , via a high speed data connection such as usb 2 . 0 , which for example , has raw data speed of 480 mb / s . each 2 mega - pixel or above frame of image is captured in one instantaneous snapshot of the entire surface area , without the need of line by line scanning , and has a resolution of at least 6 × the resolution of a vga display often found in projectors . with an embodiment of 5 mega - pixel disu lens resolution which allows for capturing images of significantly higher resolution than traditional products , the resolution of the present system will always be higher than the resolution of a display screen , for example , wherein the video frames are 16 × the resolution of a vga monitor . the spu 303 executing within the pc can display the captured video frames at enlarged or reduced sizes at the user &# 39 ; s control through a pointer device or keyboard , for example , using the mouse wheel to enlarge or shrink image sizes . additional manipulation of the image to increase resolution even further could include background filtering and advanced interpolation , up to combining multiple images into “ super resolution ” images . since the captured images are most often multiple times larger than the resolution of most computer monitor screens , the changes in image display sizes achieve the effect of zooming - in or zooming - out in real - time , digitally in computer software . for higher than actual sized magnification , an extrapolation algorithm can be employed to enlarge the original images with a certain level of pixelation effect , but achieves several magnitudes of higher magnification . at the same time , a user can click one button displayed in user interface software constructs to capture a still image of equally high resolution image of the object appearing under optical lens , so that in an embodiment having a 5 mega - pixel lens , the still image of a letter sized page can reach approximately 300 dpi resolution . ultimately , as imaging resolution increases to 20 to 30 mega - pixel range , one can achieve image resolution approaching near 600 dpi . the spu 303 software processing can also auto - crop to trim off unwanted color around the edges of the target document , and straighten the images , remove glare spots , in real - time or in offline mode , to further reduce any need to adjust the lens assembly to aim or preset a scan area . as shown in fig4 , the inventive method includes a variety of different operations that can be performed in a variety of sequences ; however , the order shown in fig4 and 5 is preferred . step 402 is a decision step wherein the disu is validated . if the disu is invalidated , the system moves to operation step 404 for error processing ; however , if the disu is validated , the system moves to operation step 406 , which is the initial boot sequence . after the system is booted , an output resolution of the sensor is selected at step 408 . at steps 410 and 412 , the system acquires a video stream that contains a plurality of video frame images and opens a data output port . frame validation occurs at decision step 414 . if there is a problem with the frame image , the system proceeds to step 416 for error processing ; however , if the frame image is acceptable , the frame is encoded into a usb data stream at step 418 , the usb data stream is outputted ( at operation step 420 ) and steps 412 through 420 are repeated until the end of the video stream is reached ( at decision step 422 ). with reference to fig5 , the process shown in fig4 continues to step 502 wherein live video stream from the usb is acquired . a maximum resolution per frame image is set and step 504 and a bitmap image is acquired as a video stream at step 506 . a resolution of a display screen is determined at step 508 and the bitmap image is scaled to fit the display screen size at step 510 . beginning at operation step 512 , a video bitmap stream is continuously rendered on the display screen . the user can select any of the functions that are shown in decision steps 514 a - 514 f . at decision step 514 a the system determines whether the user has selected a scaling ( re - sizing ) event . if the user has selected a scaling event , each video frame is enlarged or reduced at operation step 516 a by the requested amount . at decision step 514 b the system determines whether the user has selected a panning ( scrolling ) event . if the user has selected a panning event , the system at step 516 b offsets each frame image by a vector that is proportional to a magnitude that has been requested by the user . at decision step 514 c , the system determines whether the user has selected a rotation event ; if so , the system at step 516 c rotates each frame image by an angle that is proportional to the magnitude of rotation selected by the user . at decision step 514 d , the system determines whether the user has selected a cropping event . if the user has selected a cropping event , the system proceeds to step 516 d and each image frame is reduced such that only the area inside of a crop box will be displayed on the display screen . at decision step 514 e , the system determines whether an image event is being captured , i . e ., whether a screen shot is being requested , if so , at operation step 516 e , the system will capture whatever frame image is displayed during the time of the request and / or shortly thereafter and before the request and will save the frame image in a file or memory . at decision step 514 f the system determines whether a video event is being recorded . if the answer to decision step 514 f is yes , the system at step 516 f will capture multiple continuous frame images to save in a memory or file for later playback . also it is useful to note that the system can continually look for user interfaces ( at step 518 ) that would prompt decision steps 514 a - 514 f , the system can intermittently look for such user interfaces and / or the user can look for these user interfaces only upon request by the user . additional features of the present system are shown in fig6 . non - user controlled features such as auto - cropping processing 602 , auto straightening processing 604 , auto - correction processing 606 , auto - shadow removal processing 608 , automatic glare spot removal 610 and image file management 612 are available to a user via touch sensitive display screen 614 or other user interface means . also , commands 616 a , 616 b , and 616 c can be manually selected by the user . by offloading the processing of zooming functions to the spu 303 software on pc 301 , the present system has eliminated the need for an optical zoom lens assembly , which is high cost and considerably heavy . instead , an externally attached apparatus can use very lightweight optical components such as one might find in a camera equipped mobile telephone or an infinite focal length digital camera , and with much reduced electronic or firmware processing . such an integrated system of real - time image processing software working in conjunction with the external digital imaging unit , allows achievement of all of the desired properties , as mentioned previously , to include , displaying real - time video preview with a high zoom capability . the system can be configured to provide a minimum of 6 × zooming - in and zooming - out , and at the same time capturing high resolution still images of 300 dpi resolution , all the while maintaining a physical unit that is highly space efficient , lightweight , of a small base foot - print of no more than 10 square inches , compact and highly portable . such configuration of a single disu 302 achieves the above stated desirable features without the need for an extra video camera , required in the prior art , for the purpose of assisting in and preparing for the image capturing with preview , alignment , or pre - selection of scan area . the present system offloads zooming and other optical functions from the lens assembly to the integrated computer software processing unit using digital zooming and other image processing techniques , coupled with a miniaturized high resolution image sensing unit capable of taking a full page picture instantaneously and hd real - time video within the same unit . the present system is also highly compact and lightweight , thereby enabling a high degree of portability and space - efficiency . furthermore , the system and method are novel in the aspect that they fulfill functions of both document camera systems and document scanner devices and presentation and video display devices , hence the device described in the present system is recognized by popular computer operations systems , such as microsoft windows ®, mac os x ®, or linux ®, as a dual identity device , currently as a usb connected web camera device and a twain scanner device at the same time . the dual identity aspect of the device qualifies the system in the present invention as a new device category , which we consider as camera - scanner devices . the previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention . various modifications to these embodiments will be readily apparent to those skilled in the art , and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention . for example , one or more elements can be rearranged and / or combined , or additional elements may be added . thus , the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein .