Tag Archives: Dev

Extracting SURF features – convenience command line utility for Windows

Sometimes you just need a small command line utility to extract some local feature from an image … and you have no time to set up and compile OpenCV right this time. Here’s the solution: I did the task (actually for my students and for me, but still you might use it :).

The utility is absolutely basic stuff. Just start “extractSurf.exe” on Windows 7, give it an image as first parameter and it will spit out the surf feature descriptors (on stdout) headed by the x and y coordinates and the response value. Source - of course - is also provided … but it’s not magic. It’s all about the convenience of the binary.

Links to the OpenCV wiki on how to compile the stuff are provided in a small README in the source archive.


  • extractSurf-bin.7z - (7Z archive, Win7 32 bit binary, 1.5M)
  • extractSurf-src.7z - (7Z archive, C++ code and CMake file, 1.2K)

Search through a million images in less than a second

We reached a milestone here! Sebastian Kielmann reported that he used LIRe to index a million images. While that’s actually no problem he further managed to search through the images in < 1 second! Whoot!

Sebastian used the metric index, which implements the ideas of Giuseppe Amato. The approach is easy, but works out really fine. Currently CEDD is the standard descriptor, but others are integrated easily.  However, using the metric index is not trivial and requires some knowledge on the process. Also the results are approximate and might differ from the results obtained by linear search.


  • Sebastian report on the 1 mio. images search
  • Giuseppe Amato

Best of compiler construction

In general one should not post errors of other … but well I just give the best answers, no questions, no names … and of course: it’s a good laugh 😀

Notation for describing graphs is not quite clear to some people. I also miss the mother nodes: […] nodes in the dependency graph are depending on father nodes, sister nodes and brother nodes […]

Asking for advantages and disadvantages of a certain approach I got within the same answer: […] advantage: program is faster, disadvantage: program would be slower […]

Please note that I assume that these answer come out of the stress of the people writing the test and not the missing knowledge.