GetComponentData

Description

Returns the two-dimensional array of pixel values in the specified color component of the current frame.


Syntax

[VB]
Value=objActiveDcam.GetComponentData( Component )

[C/C++]
HRESULT GetComponentData( short Component, VARIANT* pArray );


Data Types [VB]

Y: Integer
Component: Integer
Return value: Variant (SAFEARRAY)


Parameters [C/C++]

Component [in]

The index of the selected color component (0 - Red, 1 - Green, 2 - Blue)

pArray [out,retval]

Pointer to the SAFEARRAY containing the pixel values in the frame

Return Values

S_OK

Success

E_FAIL

Failure.

E_INVALIDARG

Invalid input argument.

Example

This VB example grabs a frame, retrieves its green component and displays the value of the specified element of the array.

Dim pix as Long
ActiveDcam1.Grab
DataArray=ActiveDcam1.GetComponentData(1)
x=16
y=32
pix=DataArray(x,y)
if pix < 0 then
pix=65535-pix
endif


Remarks

The array returned by GetComponentData has the dimensions 0 to SizeX - 1, 0 to SizeY - 1. The type of data in the array depends on the format of the video acquired. For the 24-bit video the method will return an array of bytes. If the video is of the high-bit depth, the array will contain integer (word) values.

Note that modifying elements of the array will not change actual pixel values in the frame buffer. The image data in the array 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. This is opposite to the order of raws in the array returned by GetImageData.

If the video has a grayscale format, the Component parameter will have no effect and the output array will contain the luminance data.

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, subract them from 65535 (see the example above).

Note that in C/C++ applications it is required to call SafeArrayDestroy() to delete the SAFEARRAY returned by GetComponentData..