Table Of Contents

Lookup (Math Lookup) (G Dataflow)

Last Modified: June 25, 2019

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

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image src

Reference to the source image.

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image mask

8-bit image that specifies the region of the small image to be copied.

Only pixels in the image src image that correspond to a 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

Reference to the destination image.

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function

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. 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. You can choose from the following valid operators:

Name Description
Linear (Default) Linear remapping.
Log A logarithmic remapping operation that gives extended contrast for small pixel values and less contrast for large pixel values.
Exp An exponential remapping operation that gives extended contrast for large pixel values and less contrast for small pixel values.
Square Similar to exponential but with a more gradual effect.
Square Root Similar to logarithmic but with a more gradual effect.
Power X Gives variable effects depending on the value of X. The default value of X is 1.5.
Power 1/X Gives variable effects depending on the value of X. The default value of X is 1.5.

Default: Linear

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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x value

Value used only for the operators power x and power 1/x.

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range

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, the node 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. The VI does not modify the dynamic range for 16-bit and floating-point images. The VI changes only the distribution of the values. The node does not modify the dynamic range for 16-bit and floating-point images. The node changes only the distribution of the values.

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minimum

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

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.

Default: (0, 0)

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image dst out

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

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application


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