F_VN_LaplacianFilterExp

Syntax

Definition:

FUNCTION F_VN_LaplacianFilterExp : HRESULT
VAR_INPUT
    ipSrcImage  : ITcVnImage;
    ipDestImage : Reference To  ITcVnImage;
    eDestDepth  : ETcVnElementType;
    nKernelSize : UDINT;
    fScale      : LREAL;
    fDelta      : LREAL;
    eBorderType : ETcVnBorderInterpolationMethod;
    hrPrev      : HRESULT;
END_VAR

Inputs

Name	Type	Description
ipSrcImage	ITcVnImage	Source image
ipDestImage	Reference To ITcVnImage	Destination image (An appropriate destination image will be created if required.)
eDestDepth	ETcVnElementType	Destination image depth
nKernelSize	UDINT	Aperture size used to compute the second-derivative filters (1, 3, 5, ..., 31)
fScale	LREAL	Scale factor for the computed derivative values
fDelta	LREAL	Delta value that is added to the results before storing them
eBorderType	ETcVnBorderInterpolationMethod	Image border handling
hrPrev	HRESULT	HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)

Return value

HRESULT

Further information

The function F_VN_LaplacianFilterExp is the expert version of F_VN_LaplacianFilter. It contains additional parameters.

Parameter

Input image

The input image ipSrcImage may be in any available format, except for the data types SINT and DINT, which are generally not supported.

Result image

The result image ipDestImage has the same size as the input image ipSrcImage, but the pixel format is determined by the result depth eDestDepth.

Result depth

The result depth eDestDepth defines which element type the result image ipDestImage has. A larger element type can display more information.

Notice

Combination of input image and result depth

Only the same or a larger data type than that of the input image can be used as the result depth, otherwise data would be lost. For example, a UINT cannot be converted to a USINT. Furthermore, there are two restrictions, so that a UINT cannot be converted into an INT and a REAL cannot be converted into an LREAL.

Kernel size

The parameter nKernelSize defines the size of the filter kernel for the approximation of the 2nd derivative. Only odd numbers between 1 and 31 are allowed.

Scaling

The result of the Laplace operation is multiplied by the scaling factor fScale.

Delta

The constant delta fDelta is added to the result of the Scharr operation after scaling with fScale.

Border extrapolation

The method of border extrapolation eBorderType defines how non-existent pixels are extrapolated beyond the image border in order to calculate the filter values at the image borders. For further details, see ETcVnBorderInterpolationMethod.

Application

The application of a Laplace filter with a kernel size of 3×3 looks like this, for example:

hr := F_VN_LaplacianFilterExp(
    ipSrcImage  :=  ipImageIn,
    ipDestImage :=  ipImageRes,
    eDestDepth  :=  TCVN_ET_USINT,
    nKernelSize :=  3,
    fScale      :=  1,
    fDelta      :=  0,
    eBorderType :=  TCVN_BIM_DEFAULT,
    hrPrev      :=  hr
);

Samples

Edge detection filters

Required License

TC3 Vision Base

System Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT V3.1.4024.54 or later	PC or CX (x64) with PL50, e.g. Intel 4-core Atom CPU	Tc3_Vision