Category: All

All posts across the whole website belong to this category. They might also belong to some other categories as well, but this one holds all of them. Hence the descriptive name – All.

Überlingen mid-air collision

This accident has recently came up in a conversation I had with a few friends.  Surprisingly, it’s not as widely known as I thought it was.  Read through the Wikipedia page for more details.

The Überlingen mid-air collision occurred at 21:35 UTC on 1 July 2002 between Bashkirian Airlines Flight 2937 (a Tupolev Tu-154M passenger jet carrying 60 passengers – mostly children – and 9 crew) and DHL Flight 611 (a Boeing 757-23APF cargo jet manned by two pilots) over the towns of Überlingen and Owingen in southern Germany. All 71 people on board the two aircraft were killed.

Nearly two years later, on 24 February 2004, Peter Nielsen, the air traffic controller on duty at the time of the accident, was stabbed to death by an architect, Vitaly Kaloyev, who had lost his wife and two children in the accident.

On 19 May 2004, the German Federal Bureau of Aircraft Accidents Investigation (BFU) published its determination that the accident had been caused by shortcomings in the Swiss air traffic control system supervising the flights at the time of the accident and by ambiguities in the use of TCAS, the on-board aircraft collision avoidance system.

This is obviously very tragic, but what a story!  I’ve heard a rumor that there will be a drama movie made about it. That’s in addition to a few documentaries that already exist. Like this one, for example:

Reducing the size of PNG images

I had an interesting problem today.  I was uploading a third-party theme to a WordPress hosted on the server that I don’t control and really don’t have much access to.  The server had a limitation of the upload size set to 10 MB.  Yeah, I know.  But not much I could do about that.  The theme that I was uploading was packed into an 11 MB ZIP file.  The theme itself was rather complicated (one of those commercially developed themes that are based on a framework and bring in a few plugins required for their functionality), so I couldn’t really remove anything from it.

Upon a quick inspection, I realized that more than half of the ZIP weight is due to a multitude of PNG images.   And while some image were small and legitimate – like, say, icons – quite a few others were packing lots of bytes for nothing – demos, sample images, and such.  Obviously, I wanted to reduce the size of these files significantly.

My usual tool of choice for such tasks is usually ImageMagick.  To tell you the truth, I rarely work with PNG images.  JPEGs are a more frequent target for me.  So, I didn’t realize that ImageMagick handles -quality parameter differently for different image formats as fast as I’d like.  But even when I did, the results weren’t all that great.  In fact, the file sizes slightly grew in my tests.

Looking for a different approach, I came across this article about a tool called optipng, which can be conveniently installed in Fedora via yum.  Unleashing this tool onto my PNG image collection showed me that whoever made the WordPress theme new what they were doing.  opmipng reported that all images are already optimized and there isn’t much to do.

That’s when I found yet another tool to play with.  This discussion at StackOverflow SuperUser suggests pngquant, which is also a breeze to install on Fedora with yum.  So finally, I did something like this:

$ sudo yum install -y pngquant
$ cd folder/with/images
$ pngquant --force --ext .png --quality=0-75 *.png

That gave me exactly what I needed – a sufficient enough reduction in file sizes for the ZIP archive to fit into the upload limit set on the server.