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MVTec Halcon wrapper with XLD serialization

version 1.0.4 (9.96 KB) by T. Dunker
Matlab wrapper for MVTec Halcon functions with XLD serialization


Updated 01 Apr 2020

GitHub view license on GitHub

This MVTec Halcon wrapper can pass HObjects of type XLD between functions. The XLD is not mapped to a Matlab structure. It is simply serialized to a byte stream.

The build process is packed into the function build(). Executing build() will create a new folder "../halcon-XXX-YYY-ZZZ/+halcon", where XXX stands for the Halcon version, YYY for the matlab('arch') and ZZZ for the short name of the mex C++ compiler.

After adding the "halcon-XXX-YYY-ZZZ" folder to the matlab path one can e.g. use the model finding functions
xld = halcon.EdgesSubPix(templateImage, ...);
modelId = halcon.CreateScaledShapeModelXld(xld, ...);
[rows, cols, angles, scales, scores] = halcon.FindScaledShapeModel(searchImage, modelId, ...);

Cite As

T. Dunker (2020). MVTec Halcon wrapper with XLD serialization (, GitHub. Retrieved .

Comments and Ratings (4)

T. Dunker

The problem is that the mex function (DLL, Windows) can not be unloaded. The HALCON 12.0.3 / Programmer's Guide / Tips and Tricks chapter 3.2 "Terminate HALCON Library" says the following:
"In applications where DLLs are unloaded in a thread-exclusive context (such as applications using COM), the HALCON library will not terminate properly if the thread pool is still active, except when using the HALCON/COM interface.
To overcome this problem, it is necessary to either call set_system('thread_pool','false') early enough before terminating the application (typically in the main application windows close event), or to disable thread pool cleanup by setting HShutdownThreadPool = FALSE at any time."
Actually, in the beginning of each mex file from the package SetSystem("thread_pool", "false") is called.

T. Dunker

After using a Halcon function Matlab can not clear its complete workspace any more, e.g.
>> clear all
>> num = halcon.GetSystem('thread_num')
num =
>> clear all
will not return. In contrast, clearing only Matlab variables like ">>clear num" works correctly. I use "taskkill /f /im matlab.exe" to finish Matlab after using Halcon. So far I could not identify the reason.

sike xu

I found it! Just use function GetContourXld()~

sike xu

Thanks for sharing. I also want to ask how to use the byte stream in matlab. Function EdgeSubPix() return structure containing a field named xld. I thought this may be the coordinates of edge. But the facts was the size of xld is n by 1. So how to transfer this variable into the coordinates:)



moved sources to


ambiguity between function and variable names removed


removed error in build.m


Prevent dynamical unloading of the dll when clearing for a halcon mex function is called by mexLock(). This avoids the hang of matlab.

MATLAB Release Compatibility
Created with R2019a
Compatible with any release
Platform Compatibility
Windows macOS Linux

Inspired by: MVTec Halcon Wrapper