GetRawData

Description

Returns the two-dimensional array of values in the currently acquired data buffer or pointer to this buffer.


Syntax

[VB]
Value=objActiveDcam.GetRawData ([isPointer=False])

[C/C++]
HRESULT GetRawData(  bool isPointer, VARIANT* pArray );


Data Types [VB]

Return value: Variant (SAFEARRAY)


Parameters [C/C++]

isPointer [in]

If false returns the array of raw data, otherwise returns pointer to data.

pArray [out,retval]

Pointer to the SAFEARRAY containing the raw data buffer.

Return Values

S_OK

Success

E_FAIL

Failure.

Example

This VB example grabs a frame, retrieves the raw data array and displays the value of the specified element of the array.

Dim pix as Long
ActiveDcam1.Grab
RawData=ActiveDcam1.GetRawData
x=16
y=32
pix=RawData(x,y)
if pix < 0 then
pix=65535-pix
endif
MsgBox RawData(x,y)

Remarks

This function returns the frame data as they arrive from the camera (before being converted to a viewable format, such as RGB). GetRawData does not decode the image data, so the array returned contains the actual image buffer of the currently acquired frame. Modifying elements of the array will change actual pixel values in the image buffer. This can be used to perform custom image processing and display a processed image in real time. Note that this feature cannot be used in .NET as its framework creates a copy of the array returned. For direct access to raw data in C# set isPointer to True and use the poitner instead of an array.

Raw image data are stored in the standard order from top to bottom, therefore the first element of the array is first pixel of the top line of the image. The type of data and dimensions of the array returned by GetRawData depends on the ouput format of the video, its horizontal width SizeX and the number of lines acquired, as specified in the following table:

Format	Data type	Dimensions
Mono (8)	Byte	0 to SizeX -1, 0 to Lines - 1
Raw Color (8)	Byte	0 to SizeX -1, 0 to Lines - 1
YUV (4:1:1)	Byte	0 to SizeX*3/2 -1, 0 to Lines - 1
YUV (4:2:2)	Integer (word)	0 to SizeX -1, 0 to Lines - 1
YUV (4:4:4)	Integer (word)	0 to SizeX -1, 0 to Lines - 1
Mono (16)	Integer (word)	0 to SizeX -1, 0 to Lines - 1
Raw Color (16)	Integer (word)	0 to SizeX -1, 0 to Lines - 1
RGB (8:8:8)	Byte	0 to SizeX * 3 - 1, 0 to Lines - 1
RGB (16:16:16)	Integer (word)	0 to SizeX * 3 - 1, 0 to Lines - 1

For integer (word) type of data you can receive negative numbers if pixel values exceed 32767. In C and C# you can convert signed integers to unsigned ones by using data casting. To get rid of negative values in VB and Delphi, subtract them from 65535 (see the example above).

Note that setting both Display and Magnification properties to zero will disable an image conversion pipeline that is normally applied to each raw frame. This will significantly increase the performance of your application as long as it does not utilize ActiveDcam's built-in image decoding/display.