Accessing Webcam Through MATLAB Code

It is actually possible to access various hardware, with MATLAB codes. One of the hardware is your Webcam, in order to take a video or a Picture as an input.

The functions we are going to use for it is: "videoinput" & "preview"
This "videoinput" function creates a "video input object" which can be used for previewing the video through "preview" function.

So code will be like: 
%start of code
clc;
vid = videoinput('winvideo', 1, '
YUY2_640x480');
preview(vid);

 %end of code

Preview of how output will be:

Accessing Webcam Through MATLAB Code: videoinput & preview functions
Accessing Webcam Through MATLAB Code


Click here to see How to Acquire An Image From Webcam, Using MATLAB Code.
Click here to see How to Record a Video From Webcam Using MATLAB Code.

Details of videoinput & preview function:

"videoinput" function:

v = videoinput(Adapter_name)    or
v = videoinput(Adapter_name, Device_ID)    or
v = videoinput(Adapter_name, Device_ID, Format)


# here 'v' is the video object created after executing the "videoinput" function.
# here "Adapter_name" is a string that specifies the name of the adapter used to communicate with that particular device.

NOTE: Use the "imaqhwinfo" function to determine the adaptors available on your system. Its output will be like: 
>> imaqhwinfo
ans = InstalledAdaptors: {'gentl'  'gige'  'matrox'  'ni'  'winvideo'}
         MATLABVersion: '8.0 (R2012b)'
         ToolboxName: 'Image Acquisition Toolbox'
         ToolboxVersion: '4.4 (R2012b)'

With these info., we can use 'gentl' or 'gige' or 'matrox' or 'ni' or 'winvideo' as Adapter_name.

# here Device_ID is a numeric scalar value that identifies a particular device available through the specified adaptor, Adapter_name.

NOTE: Use the "imaqhwinfo(Adapter_name)" syntax to determine the devices available through the specified adaptor. If Device_ID is not specified, the first available device ID is used. For convenience, a device's name can be used in place of the Device_ID. If multiple devices have the same name, the first available device is used.

Its output will be like:
>> imaqhwinfo('ni')
ans = AdaptorDllName: [1x68 char]
          AdaptorDllVersion: '4.4 (R2012b)'
          AdaptorName: 'ni'
          DeviceIDs: {1x0 cell}
          DeviceInfo: [1x0 struct]

# In this case the AdapterName is 'ni', but its device id is not clear, so we can use its name instead of Device_ID.

>> imaqhwinfo('winvideo')
ans = AdaptorDllName: [1x74 char]
          AdaptorDllVersion: '4.4 (R2012b)'
          AdaptorName: 'winvideo'
          DeviceIDs: {[1]}
          DeviceInfo: [1x1 struct]

# In this case the AdapterName is 'winvideo', & its device id is '1', so we can use this value as Device_ID.

# FORMAT is a text string that specifies a particular video format supported by the device
NOTE:
To get a list of the formats supported by a particular device, view the DeviceInfo structure for the device that is returned by the imaqhwinfo  function. Each DeviceInfo structure contains a SupportedFormats field. If FORMAT is not specified, the device's default format is used.

SAMPLE OUTPUT:
>> a=imaqhwinfo('winvideo');
>> a.DeviceInfo.SupportedFormats

ans =

  Columns 1 through 4

    'YUY2_1280x1024'    'YUY2_1280x800'    'YUY2_160x120'    'YUY2_176x144'

  Columns 5 through 7

    'YUY2_320x240'    'YUY2_352x288'    'YUY2_640x480'


Here 'YUY2_1280x1024' , 'YUY2_1280x800'  ,  'YUY2_160x120'  ,  'YUY2_176x144' ,
'YUY2_320x240'  ,  'YUY2_352x288'  &  'YUY2_640x480' are the supported video format of the device_name 'winvideo' use that.


"preview" function:

It Display preview of live video data. preview(v) creates a Video Preview window that displays live video data for video input object 'v'. The window also displays the timestamp & video resolution of each frame, and the current status of 'v'. The Video Preview window displays the video data at 100% magnification (1:1).

Team Digital iVision Lab!

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