OpenCV trackbars and OS X


Notoriously poor coding by the OpenCV group here, with trackbars being barely functional.

The two main issues are:

  • Trackbar value is not displayed
  • Trackbar ordering is not the same as the order in which they are coded
    • In fact is is apparently random, or pseudo-random – it is a logic, but it is not clear what that logic is

Additional issues are:

  • Named windows containing only trackbars do not move with moveWindow()
  • Named windows containing only trackbars do not resize with resizeWindow() – check this!!!
  • Code execution pauses when a trackbar is adjusted
  • Performance hits
    • When trackbars are in the same window as the image being adjusted

I have seen these issues consistently in Python. I am not sure if they all occur in C++ as I haven’t tested for them (yet).

Version info:

  • OS X: High Sierra
  • Python 3.7/3.9
  • OpenCV:

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Converting (PNG/TIFF and) ICO to ICNS – basically.

Harking back to the serialplot application, see HOWTO: Port serialplot to OS X, I decided to use the provided ICO file, to give the OS X application an icon. Sounds easy, right?

Use imagemagick, or don’t… personally, I wouldn’t bother…

Doing it manually, as I want to avoid using the most annoying Xcode, which makes life way too easy. Let’s set the icon in the most difficult way possible

Continue reading Icons

Course notes: Another Arduino based robot car


Notes from Robotics Training LESSON 1: An Introduction to Robotics for Absolute Beginners

Yet another robot car, based on Arduino. This project uses the Elegoo robot car.

It’s interesting to compare this one with the Murtaza car projects. The movement functions are more sophistimcated on this project.


Note that this course code is for V3 of the Elegoo car. V3+ and V4 will not work, without some modification.

Continue reading Course notes: Another Arduino based robot car

Sick of Apples? Compile OS X applications using Ubuntu


[Credit where credit is due, my mate Rodders inspired this article.]

The love affair could be finally over…

As I’ve been “thinking different” since ’88, I never thought I’d say this but… for a few months now Apple have been winding me up. So much so, in fact, that I’m nearing a point where I want to ditch them completely… or, rather, the OS…

Continue reading Sick of Apples? Compile OS X applications using Ubuntu

HOWTO: Port serialplot to OS X


A brief HOWTO explaining the OS X porting process for /serialplot.

For a detailed voyage of discovery, see Porting serialplot to OS X.

This application is not to be confused with /SerialPlot (note the capitalisation), a Qt application written explicitly for OS X, see Compiling Qt SerialPlot (for OS X).

Note: Using OS X 10.13.6 High Sierra

Application and script: /serialplot_OS_X_port

Continue reading HOWTO: Port serialplot to OS X