GetImageWindow

Description

Returns the two-dimensional array of pixel values corresponding to the selected window in the currently acquired frame.


Syntax

[VB]
Value=objActiveGige.GetImageWindow (X, Y, Width, Height)

[C/C++]
HRESULT GetImageWindow( short X, short Y, short Width, short Height, VARIANT* pArray );


Data Types [VB]

X,Y, Width, Height: Integer
Return value: Variant (SAFEARRAY)


Parameters [C/C++]

X [in], Y[in]

The x- and y-coordinates of the top left pixel of the window in the entire frame

Width [in], Height [in]

The horizontal and vertical size of the window in pixels.

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 increase the brightness in the central area of the live image:

Private Sub Form_Load()
ActiveGige1.Display = False
ActiveGige1.Acquire = True
End Sub
Private Sub ActiveGige1_FrameAcquired()
xc = ActiveGige1.SizeX / 2
yc = ActiveGige1.SizeY / 2
w = ActiveGige1.GetImageWindow(xc - 70, yc - 50, 140, 100)
For y = 0 To UBound(w, 2)
For x = 0 To UBound(w, 1)
pix = w(x, y) + 50
If pix > 255 Then
pix = 255
End If
w(x, y) = pix
Next
Next
ActiveGige1.SetImageWindow xc - 70, yc - 50, w
ActiveGige1.Draw
End Sub

Remarks

The image data in the array are stored in the standard order from top to bottom, therefore the first element of the array is the top left pixel of the window. This is opposite to the order of rows in the arrays returned by GetImageData. The type of data and dimensions of the array returned by GetImageWindow depends on the output format of the video, the width and height of the window 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

If the dimensions of the window are too large to accommodate the frame size, they will be clipped to the frame boundaries.

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.

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.

Note that modifying elements of the array will not change actual pixel values in the frame buffer. Use SetImageWindow to transfer pixel values into ActiveGige.

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