Table Of Contents

Estimate Flat Field Model (G Dataflow)

Last Modified: June 25, 2019

Returns a flat field image by fitting a mathematical model on the supplied image.

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ROI descriptor

Region of interest (ROI) within which the flat field operation is computed.

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global rectangle

Coordinates of the bounding rectangle.

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contours

Individual shapes that define an ROI.

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ID

Object specifying if contour is the external or internal edge of an ROI.

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Type

Shape type of the contour.

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Coordinates

Relative position of the contour.

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image src

Reference to the source image.

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image dst

Reference to destination flat field image.

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mask image

Reference to the mask image.

The mask image represents the background region on image src.

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surface fit options

Cluster of options used to determine the surface fit to construct the flat field image.

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model

Input that specifies the surface fitting model.

Name Description
Polynomial Uses a 2D polynomial mathematical model to determine the image.
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sampling grid size

Cluster specifying the size of the grid the node uses when fitting the model.

The larger the grid size, the more accurate the fit will be. The time to estimate the flat field image will increase with a larger grid size.

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sizeX

Size of the window in the x-dimension.

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sizeY

Size of the window in the y-dimension.

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polynomial degree

Input that specifies the polynomial degree the algorithm uses to estimate the background of the image.

The time to estimate the flat field image increases with a higher degree.

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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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background estimation options

Cluster of options used to estimate the background region of image src.

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estimate background?

Input that enables background estimation algorithm when set to TRUE.

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method

Input that selects the method the algorithm uses to estimate the background of the model image.

Name Value Description
polynomial 0

Uses a polynomial algorithm with a specified polynomial degree to estimate the background.

background correction 1

Performs background correction to eliminate non-uniform lighting effects and then performs thresholding using the interclass variance thresholding algorithm.

NiBlack 2

Computes thresholds for each pixel based on its local statistics using the NiBlack local thresholding algorithm.

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polynomial degree

Input that specifies the polynomial degree the algorithm uses to estimate the background of the image.

The time to estimate the flat field image increases with a higher degree.

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window size (32x32)

Cluster specifying the size of the window the node uses when calculating a local threshold.

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sizeX

Size of the window in the x-dimension.

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sizeY

Size of the window in the y-dimension.

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Niblack deviation factor in

Input that specifies the k constant used in the Niblack local thresholding algorithm, which determines the weight applied to the variance calculation.

Valid k constants range from 0 to 1. The lower the deviation factor, the closer the pixel value must be to the mean value selected as part of a particle. Setting the Niblack deviation factor in to 0 increases the performance of the node, as the pixel variance is not calculated.

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flat field image out

Estimated flat field image.

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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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