alt Hacker NewsDone a few projects with OpenCV over the years, and I agree it can be fun.
However, it has a few issues:
1. Patented algorithms that are effectively impossible to license in a commercial setting.
2. Permuted API that change how identically named functions behave over versions.
3. Hardware CUDA version coupling deprecating support every major release.
4. Inconsistent and contradictory documentation in the constant subtle permutations. Downstream projects tend to version lock the lib for really practical reasons.
5. A shift away from core C libraries like ImageMagick & V4l, and into C++ abstractions with legacy Swig wrapper libraries in Java or Python.
6. Perpetual-Beta culture means the library will unlikely ever really fully stabilize.
It is a fun library, until people actually try to deploy something serious. As users will often simply suggest using an old version release if there is a bug.
Everything from Build flags to the API documentation has never fully stabilized. ymmv =3
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Also, performance is generally pretty low; I've been on projects where we rewrote OpenCV code into more-or-less obvious hand-rolled code and won 5x perf. The abstractions are generally a bit too thick and oriented around single pixels (which also makes the API a bit too verbose for my taste).
Agree with this too. OpenCV is functionality great but its constituent parts are written by many different people who all kind of do things a little differently and it shows.
But I can’t really complain because it’s open source and added to by contributors.
Done a few projects with OpenCV myself, and your list of issues reads as if you throw OpenCV and opencv_contrib into the same bucket. Which you shouldnt. And maybe your assessment is outdated here and there and it is time to look again.
- OpenCV is Apache license. Yes, it used to be more complicated.
- The only patented algorithm I am aware of, SIFT, used to be part of opencv_contrib. And the README in opencv_contrib would greet you with a warning, that the code may not be fit commercial use for various reasons. Only when the patent expired, it was moved into OpenCV core.
- Same observation for Aruco marker detection, which was in contrib for a long time because the options to choose from were either not-well-maintained or GPL-licensed code. It is now in core OpenCV (and Apache).
- Despite its age, I think that OpenCV is still more than relevant today. And being part of modern languages like C++, Swig, Java and Python (and for years already) is part of that. Still I was surprised how long they maintained OpenCV 2 and 3.
- Over the past releases and few years, my impression was actually that core API was very much stable(izing). Cant say what happened in contrib – or what it feels like when you treat core and contribute as one and a feature progressed from contributing to core.
- I do agree, that I usually I would check that a MINOR releases wasnt actually a MAJOR release, breaking some API or behavior I was relying on. I am hoping that Version 5 is pulling the ambitions for making things differently away from Version 4. So v4 can be used stably ;-)