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FIL.LogarithmImage

Computes a natural logarithm of each pixel.

Namespace:FilNet
Assembly:FIL.NET.dll

Syntax

C++
C#
 
public static void LogarithmImage
(
	FilNet.Image inImage,
	NullableRef<FilNet.Region> inRoi,
	float? inScale,
	float inOffset,
	bool inNormalizeZero,
	FilNet.Image outImage,
	FilNet.Profile diagLutProfile
)

Parameters

Name Type Range Default Description
inImageFilNet.ImageInput image.
inRoiFilNet.NullableRef<FilNet.Region>Region of interest. Default value: ftl::NIL.
inScalefloat?Scaling factor (default: 255). Default value: ftl::NIL.
inOffsetfloat<1.0f, INF>1.0fOffset factor. Default value: 1.0f.
inNormalizeZeroboolSpecifies whether the output range should be rescaled to start from 0.
outImageFilNet.ImageOutput image.
diagLutProfileFilNet.ProfileProfile depicting the resulting look-up table of the logarithm transform.

Description

The operation applies logarithmic operator to each pixel of an image. Logarithmic operator is defined as follows:

\[inScale \cdot \frac{log(inOffset + |P(x,y)|)}{log(inOffset + M)}\]
where:

  • M is the maximum of the inImage type (i.e. 255 for UInt8, 127 for Int8).
  • inScale is the expected maximum value of the transformation. If set to Auto it will result in value 127 for Int8 image and 255 for other image types.
  • inOffset value corresponds to the camera's black level. Its default value is equal 1 and causes the strongest possible transform.

When inNormalizeZero is set to True, the result is not only scaled, but also normalized so that pixel value 0 is still transformed into value 0. This assures that the entire output value range is utilized.

Examples

The LogarithmImage performed on the sample image with parameters inScale = 250, inOffset = 50. The middle image inNormalizeZero = False and the left image has inNormalizeZero = True.

Hardware Acceleration

This operation supports automatic parallelization for multicore and multiprocessor systems.

Hardware acceleration settings may be manipulated with Settings class.

Errors

List of possible exceptions:

Error type Description
DomainError Not supported inImage pixel format in LogarithmImage. Supported formats: Int8, UInt8, Int16, UInt16, Int32.

Function Overrides

See also