GetImageData

Description

Returns the two-dimensional array of pixel values in the currently acquired frame.


Syntax

[VB]
Value=objActiveGige.GetImageData

[C/C++]
HRESULT GetImageData( VARIANT* pArray );


Data Types [VB]

Return value: Variant (SAFEARRAY)


Parameters [C/C++]

pArray [out,retval]

Pointer to the SAFEARRAY containing the pixel values in the frame

Return Values

S_OK

Success

E_FAIL

Failure.

Example

This VB example uses the FrameAcquired event to invert pixel value in the bottom left corner of the current frame and display the processed frame in real time.

Private Sub Form_Load()
ActiveGige1.Display = False
ActiveGige1.Acquire = True
End Sub

Private Sub ActiveGige1_FrameAcquired()
a = ActiveGige1.GetImageData
For x = 0 To 200
For y = 0 To 200
a(x, y) = 255 - a(x, y)
Next
Next
ActiveGige1.Draw
End Sub

Remarks

GetImageData does not copy 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 ActiveGige's image frame in VB.NET and C# use GetImagePointer.

Images in ActiveGige are stored bottom up, therefore the first element of the array is first pixel of the bottom line of the image. The type of data and dimensions of the array returned by GetImageData depends on the output format of the video, its horizontal width SizeX and the number of lines acquired, as specified in the following table:

Camera Pixel Format	Output Format	Data type	Dimensions
Mono8	8-bit monochrome	Byte	0 to SizeX -1, 0 to Lines - 1
Mono10, Mono12, Mono16	16-bit gray monochrome	Integer (word)	0 to SizeX -1, 0 to Lines - 1
YUV411, YUV422, YUV444, RGB8, BGR8, Bayer8	24-bit RGB	Byte	0 to SizeX * 3 - 1, 0 to Lines - 1
RGB10, RGB12, RGB16, BGR10, BGR12, Bayer10, Bayer12, Bayer16	48-bit RGB	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.

Note that if images are transmitted by a linescan camera, the number of lines in each image can vary and be less than the vertical size of the image frame defined by the SizeY property. See GetHeight for more details.