IMAQ MathLookup VI

LabView NI Vision

IMAQ MathLookup VI

Owning Palette: ProcessingInstalled With: NI Vision Development Module

Converts the pixel values of an image by replacing them with values from a defined lookup table. This VI modifies the dynamic range of either part of an image or the complete image, depending on the type of curve chosen.

Examples

IMAQ MathLookup

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Range is a cluster containing the minimum and maximum pixel values of the range to modify. If you do not connect this cluster or you keep the default values of (0,0), the VI modifies the dynamic range of the entire image. The dynamic range of the destination image is dependent on the type of input image. The dynamic range for an 8-bit image is between 0 and 255. The dynamic range for 16-bit and floating-point images is the smallest and largest pixel value contained in the original image before processing.

Note  The VI does not modify the dynamic range for 16-bit and floating-point images. The VI changes only the distribution of the values.
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Minimum is the smallest value used for processing. After processing, all pixel values that are less than or equal to the Minimum in the original image are set to 0 for an 8-bit image. In 16-bit and floating-point images, these pixel values are set to the smallest pixel value found in the original image.

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Maximum is the largest value used for processing. After processing, all pixel values that are greater than or equal to the Maximum in the original image are set to 255 for an 8-bit image. In 16-bit and floating-point images, these pixel values are set to the largest pixel value found in the original image.

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X Value is a value used only for the operators Power X and Power 1/X.

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Image Src is a reference to the source image.

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Image Mask is an 8-bit image that specifies the region of the small image that will be copied. Only those pixels in the Image Src (Small) image that correspond to an equivalent non-zero pixel in the mask image are copied. All other pixels keep their original values. The entire image is processed if Image Mask is not connected.

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Image Dst is a reference to the destination 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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status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.

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code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.

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source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

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Operator specifies the remapping procedure to use. The horizontal axis represents the pixel values before processing (between Minimum and Maximum), and the vertical axis represents the pixel values after processing. The default is Linear. You can choose from the following valid operators:

Note  For an 8-bit image, the minimum is always 0 and the maximum is always 255. For 16-bit and floating-point images, the minimum and maximum are the endpoint values found in the image before processing.
Linear (0)

(Default) Linear remapping.

Log (1)

A logarithmic remapping operation that gives extended contrast for small pixel values and less contrast for large pixel values.

Exp (2)

An exponential remapping operation that gives extended contrast for large pixel values and less contrast for small pixel values.

Square (3)

Similar to exponential but with a more gradual effect.

Square Root (4)

Similar to logarithmic but with a more gradual effect.

Power X (5)

Gives variable effects depending on the value of X. The default value of X is 1.5.

Power 1/X (6)

Gives variable effects depending on the value of X. The default value of X is 1.5.

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Image Dst Out is a reference to the destination image. If 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.

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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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status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.

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code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.

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source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

Examples

Refer to the following for an example that uses this VI.

  • LabVIEW\examples\Vision\2. Functions\Grayscale Processing\MathLookup Example.vi