F_VN_LaplacianFilter
Apply a Laplacian filter to an image.
Syntax
Definition:
FUNCTION F_VN_LaplacianFilter : HRESULT
VAR_INPUT
ipSrcImage : ITcVnImage;
ipDestImage : Reference To ITcVnImage;
eDestDepth : ETcVnElementType;
hrPrev : HRESULT;
END_VAR
Inputs
|
Name |
Type |
Description |
|---|---|---|
|
ipSrcImage |
Source image | |
|
ipDestImage |
Reference To ITcVnImage |
Destination image (An appropriate destination image will be created if required.) |
|
eDestDepth |
Destination image depth | |
|
hrPrev |
HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.) |
Return valueFurther information
The function F_VN_LaplacianFilter applies a Laplace filter to the input image.
Algorithm
The Laplace filter can be used to detect edges by approximating the second derivative of the transitions of adjacent pixel intensities. Since the derivative also has negative values, it is advisable to use a signed element type for the result image (e.g. TCVN_ET_INT).
For nKernelSize = 3, 5, ... the Laplace filter is calculated by adding the second derivative in x- and y-direction over the specified window size. For nKernelSize = 1, the following special 3 x 3 kernel is used:
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. |
Expert parameters
The expert version F_VN_LaplacianFilterExp contains additional parameters.
Application
The application of a Laplace filter with a result depth of 8 bits looks like this, for example:
hr := F_VN_LaplacianFilter(
ipSrcImage := ipImageIn,
ipDestImage := ipImageRes,
eDestDepth := TCVN_ET_USINT,
hrPrev := hr
);
Original image | Result image |
|
|
Samples
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 |