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Chapter 3 Grayscale and Color Measurements
© National Instruments Corporation 3-3 IMAQ Visionfor LabWindows/CVIUser Manual
Hold down <Shift> while drawing an ROI if you want to constrain the ROI
to the horizontal,vertical, or diagonalaxes when possible. Use theselection
tool to position an ROI by its control points or vertices. ROIs are context
sensitive, meaning that the cursor actions differ depending on the ROI with
which you interact. For example, if you move your cursor over the side of
a rectangle, the cursor changes to indicate that you can click and drag the
side to resize the rectangle. If you want to draw more than one ROI in a
window, hold down <Ctrl> while drawing additional ROIs.
You can display the IMAQ Vision tools palette aspart of anROI constructor
window or in a separate, floating window. Follow these steps to invoke an
ROI constructor and define an ROI from within the ROI constructor
window:
1. Use
imaqConstructROI()
todisplayanimageandthetoolspalette
in an ROI constructor window, as shown in Figure 3-2.
Freehand Draw a freehand region in the image.
Action: Click on the initial position, drag to the desired shape and
release the mouse button to complete the shape.
Zoom Zoom-in or zoom-out in an image.
Action: Click on the image to zoom in. Hold down <Shift> and
clicktozoomout.
Pan Panaroundanimage.
Action: Click on an initial position, drag to the desired position
and release the mouse button to complete the pan.
Table 3-1. Tools Palette Functions (Continued)
Icon Too l Name Function