glopes's profile - activity

@StevenPuttemans can you provide a link to this numl language? I can't seem to find anything like that, except for numl.net, which I guess is probably not what you meant.

@StevenPuttemans I'm afraid I missed your point entirely. The fact that C++ is not a good interop language is not evolution. It has to do with not having a standard ABI and making extensive use of textual preprocessors. C has none of these complications and that's why it's the only interop language supported natively by Go, Ruby, D, C#, Lua, ... every single wrapper is replicating its own C API because there is simply no way to interface with C++. I'm not saying people should go back to coding native OpenCV in C, so please keep these two issues separate. I'm simply stating that OpenCV is a powerful interface for computer vision that is wanted and needed on many languages. Why make it harder by not having an automatically generated C interface?

I wonder why is there such a resistance to just making the C interface up-to-date. Is it not clear that C is the only way to interop for the majority of languages? Even for many of the "official" wrappers a "C" interface had to be made... why keep replicating the effort when you could just automatically generate a common C interface (related issue)?

I've been making this point for more than a year now. Too bad it didn't make it into the 3.0 official release. I really believe this should be the highest priority wrapper rather than having everyone literally reinvent the C wrapper... C++ is nice and all but horrible interop with pretty much everything.

@Will did you find anything else regarding this issue? I've pinpointed the change as definitely happening between 2.4.6 and 2.4.7. Changing the DLL fixes it, but the problem is that older versions can occasionally crash when opening MP4 files and the new ones don't... argh! can't find an ffmpeg version that just works!

I noticed the same slowdown on the encoding side. It does seem to be FFmpeg related, since for me the fix was to use the old opencv_ffmpeg DLL. It should be compatible, so it's really just a matter of renaming the DLL and you should be fine.

the only issue is that C is still much more compatible with other high-level languages, many support only interfacing with C and not C++. it would be nice to have an automatically generated C API, the same way that the Python, Java and MATLAB bindings are generated.

I want to cite OpenCV as part of a scientific publication. Basically I'm in the same situation described by Damien in this post from 2011: http://opencv-users.1802565.n2.nabble.com/OpenCV-Bibtex-citation-td6710578.html

The bibtex citation mentioned in the OpenCV wiki (http://opencv.willowgarage.com/wiki/CiteOpenCV) is not only vastly outdated but even worse, it is apparently now pointing to a dead link!

More specifically, the link to Dr. Dobb's Journal of Software Tools article on OpenCV reports back that no articles are found: http://www.drdobbs.com/ftp/2000/2000_11/opencv.txt

It is very concerning to have a citation in a paper that you actually cannot access in any way!

How are people working around this? Is there an updated citation block? Has anyone cited OpenCV in their own research that would care to share their own way to do it?

Thanks!

Actually, the OpenCV NuGet package should work just fine. The reason you don't see any DLLs when you first download the package is because OpenCV NuGet downloads them by demand at build time using the strategy adopted by CoApp.

This avoids having to download all possible combinations of platform/architecture when you just want to build vc11-x86. This helps ameliorate a bit the phenomenon of having binary distributions with hundreds of megabytes.

The way the package works is you just install it onto a VC++ project and hit build. It should work for Visual Studio 2012 and 2013. The advantage of the NuGet package is it automatically configures include and lib folders and also deploys the right versions of the binaries to the output directory of your currently specified target. It is to my knowledge the closest thing to a plug-and-play experience you can have on Windows and Visual Studio.

You can use the Package Manager Console, but actually the easiest way is just to use the dialog. You can find it by right-clicking on the project and selecting "Manage NuGet packages...". It is a nice intuitive GUI where you can just search for the OpenCV package and install it.

If you're having trouble configuring OpenCV on VS, you might want to try the available NuGet package: http://www.nuget.org/packages/opencv/

Just right-click on your project node, select "Manage NuGet packages...", search for opencv, install the package, and start coding. That's it :)

Yeah, unfortunately c++ does not usually play well with other languages. My first goal was to get a fully-featured C api wrapper out there with a BSD-style license, and then move on to develop C++ support. This will likely involve one of two routes: 1. either automatically generate the C interface from the new C++ API (mentioned in this post) or 2. use C++/CLI to directly generate the .NET wrapper; right now the latter has the disadvantage that it doesn't support Mono, but there's efforts underway to change this.

Thanks for the heads up. I've included the link to this question on the NuGet moderator report so hopefully they'll take this into account. Let me know if anyone from the team would like to try the OpenCV NuGet install experience with my test package. I was really delightfully surprised by how easy it is.

You can find the official project webpage here, which includes source code for the whole wrapper: https://bitbucket.org/horizongir/opencv.net

Not official, but I've prereleased a C# interface you can get from NuGet here: https://www.nuget.org/packages/OpenCV.Net/3.0.0-alpha. More details in this post: http://answers.opencv.org/question/18864/c-official-bindings-roadmap/

Hi all,

I was thinking of uploading a cross-language (C++/C#) OpenCV development package to NuGet when I found that there was already an OpenCV package uploaded. Besides being horribly outdated (v2.3.1), it doesn't even seem to follow NuGet guidelines enough that I can install it. It also has no integration with Visual Studio targets for setting up the development environment. The link to contact the package authors tells me they don't want to be contacted and the project page points to the official OpenCV site.

If no one claims ownership of this package, I will report the package as abusive on the NuGet website. If anyone at OpenCV wants to take care of the official NuGet package let me know and we can coordinate how to make this happen.

For those of you who may not be aware, NuGet just recently added support for native packages. The advantage of this is that it has the potential to make using OpenCV from inside Visual Studio literally a snap.

Just hit "Manage NuGet packages" -> Install OpenCV and you're done! You can start writing code, adding include files and build the project without even touching the project properties. The package does everything for you which is one of the sleekest ways I've seen of getting OpenCV up and running. The package I've been working on also supports both C++ and C# (in the latter it makes sure the DLLs are copied to the project output so they can be used by C# bindings).

Let me know what your thoughts are on this. I'm happy to take care of this for you guys if you don't want to lose time on it, but I really think this will be an important step for OpenCV on windows.

UPDATE (NUGET PRERELEASE): I've finally managed to contact the original owner of the NuGet package. He agreed to share write permissions so I could push a pre-release version with native support. You can find this new package in the NuGet gallery. Feel free to try it out by just creating a new C++ project on Visual Studio 2012, hitting "Manage NuGet packages" and installing the 2.4.6-nuget prerelease version of OpenCV. After installing you should be able to immediately start writing code, build your project and run it under either x86 or x64 platforms. I'll be test-driving this pre-release for at least a week, so please let me know of any issues/suggestions you encounter with the package.

Thanks!

Right now you need to copy the DLLs to the project output folder yourself so that the wrapper will run. That should be about it. I'm actually working right now on making a NuGet package that will even do this for you. Hopefully it will be up soon (stay tuned).

See above. Ended up taking a bit longer than expected, but here it is. I agree that an automatic C# wrapper would be ideal, although it's hard to automatize some of the design decisions that will really give it the .NET flavor. An automatic C interface generator would be a great first step, though.

I'm planning to release an updated C# interface to OpenCV 2.4.6 through NuGet over the next couple of days. These bindings were developed over the course of a year and include many features that I've missed from other attempts, namely:

• Very close to 100% support of the latest C API (including undocumented functions)
• Full documentation/intellisense for all supported methods, classes and enum members (arduously mined from many different sources)
• Support for exceptions
• Garbage-collector friendly:
  • GC is aware of the actual memory used by matrices and images
  • Pointers are guaranteed to survive function calls even if concurrent garbage collection happens
• Object model following C++ API as much as possible (towards future increased support of C++ API)
• BSD-style license (MIT)

I was very surprised by the decision to drop the C API, since it is still the easiest way for interoping with many high-level languages. I guess I could move my wrapper to use C++/CLI to get over this but I would then be limited to Windows-only support.

I'm very interested to follow up on efforts to do automatic generation of the C-interface. In fact, I may be even interested to contribute to it actively and push for an official C# wrapper built on top of it, if someone points me to how this was done for the other language bindings.

I was planning on doing this for my own C# interface anyway but if no one is currently working on it, I'm happy to hand you over the results.

I'll post here when I pre-release the CTP in NuGet if anyone wants to give it a try and help with the bug-hunt (although the unit test code base is growing). I'm versioning the bindings independently of OpenCV for now since the code was hand-written and it may be subject to independent changes. First pre-release will most likely be 2.5-ctp.

UPDATE: Just pushed a prerelease version of the wrapper on NuGet. Feel free to give it a try, will write a proper post when it's further along in testing.