IMAQ Subtract VI
Owning Palette: OperatorsInstalled With: NI Vision Development ModuleSubtracts one image from another or a constant from an image.
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Constant is the value subtracted from Image Src A for image-constant operations. Constant is rounded down when the image is encoded as an integer. The default is 0. |
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Image Src A is a reference to the first source image. |
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Image Dst is a reference to the destination image. |
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Image Src B is the reference to the second source image. |
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error in (no error) describes the error status before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
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Image Dst Out is the reference to the destination (output) image that receives the processing results of the VI. If the Image Dst is connected, Image Dst Out is the same as Image Dst. Otherwise, Image Dst Out refers to the image referenced by Image Src A. |
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error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.
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Details
An operation between an image and a constant occurs when Image Src B is not connected. The two possibilities are distinguished in the following equations:
Dst(x, y) = SrcA(x, y) – SrcB(x, y)
or
Dst(x, y) = SrcA(x, y) – Constant
The different image-type combinations supported by this VI are described in the following equations. The first symbol represents the image connected to Image Src A, and the second symbol represents the image type connected to Image Src B. The third symbol represents the image type that should be connected to Image Dst.
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To subtract a constant from an image, Image Dst must be connected to the same image type as the input Image Src A.
If one of the two source images is empty, the result is a copy of the other.
When an 8-bit image or constant is subtracted from an RGB image, it is subtracted from each plane of the RGB image. When IMAQ Subtract is performed on two RGB images, each color plane (red, green, and blue) of Image Src A subtracts the corresponding color plane of Image Src B. Each of these subtractions is similar to an IMAQ Subtract operation on two 8-bit images.