Re: [Haskell-cafe] Open CV or alternate image processing library for Haskell on windows?

On Mon, May 16, 2011 at 10:47 PM, Gregory Guthrie wrote:

Below is the install result. It does claim that "You must install OpenCV (development packages) prior to installing this package." I don't' see any Haskell /cabal opencv package, so am not sure what this means one has to do.

The error isn't referring to a Haskell package - it is saying that it cannot find the libraries installed on your computer. Note the line "Missing C libraries: cv, highgui, cv, highgui". These are not referring to Haskell packages - they are referring to libcv and libhighgui, whatever those are. What sort of computer are you using? Antoine

I am not familiar enough with the Haskell install and make environment to go hacking into it, I was hoping for a simple cabal install!

Thanks for the note and pointers. I am a bit surprised at the lack of graphics and Image processing libraries. I found several for Unix/Linux only, and their installs on Windows fail.

I also love Linux, but windows is the 93% market share, and our student labs are all windows. I am trying to advocate using FP in more of our undergraduate level courses, and thought this might be a good area; perhaps not.

Are the two packages for Hopencv the two on the hackage page? It looked to me like only one was claimed to be current and mostly complete. ---------------------------------------------------

C:\Users\guthrie>cabal install hopencv Resolving dependencies... Configuring HOpenCV-0.1.2.2... Warning: 'include-dirs: /usr/include/opencv' directory does not exist. Warning: 'include-dirs: /usr/include/opencv' directory does not exist. cabal: Missing dependencies on foreign libraries: * Missing C libraries: cv, highgui, cv, highgui This problem can usually be solved by installing the system packages that provide these libraries (you may need the "-dev" versions). If the libraries are already installed but in a non-standard location then you can use the flags --extra-include-dirs= and --extra-lib-dirs= to specify where they are. cabal: Error: some packages failed to install: HOpenCV-0.1.2.2 failed during the configure step. The exception was: ExitFailure 1

C:\Users\guthrie>cabal install cv Resolving dependencies... Configuring unix-2.4.2.0... cabal: The package has a './configure' script. This requires a Unix compatibility toolchain such as MinGW+MSYS or Cygwin. cabal: Error: some packages failed to install: CV-0.3.0.1 depends on unix-2.4.2.0 which failed to install. JYU-Utils-0.1.1.1 depends on unix-2.4.2.0 which failed to install. unix-2.4.2.0 failed during the configure step. The exception was: ExitFailure 1

C:\Users\guthrie>cabal install highgui cabal: There is no package named 'highgui'. You may need to run 'cabal update' to get the latest list of available packages.

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-----Original Message----- From: Casey McCann [mailto:syntaxglitch@gmail.com] Sent: Monday, May 16, 2011 1:18 PM To: Gregory Guthrie Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Open CV or alternate image processing library for Haskell on windows?

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I wanted to look into using Haskell for an introductory Image Processing class, but the main

On Mon, May 16, 2011 at 8:37 AM, Gregory Guthrie wrote: package used for such things (OpenCV) does not appear to be available for windows systems.

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Is there some other good option for image processing in Haskell, or has anyone ported

openCV to a windows Leksah environment?

Which package are you having difficulty with? OpenCV is a library written in C/C++ and appears to work on Windows, and there looks to be two different packages on Hackage providing bindings to it, neither of which seems to have any issues with Windows. One does rely on the unix package, but my understanding is that Cygwin is sufficient for that--not certain about the details, though. I haven't used any of these packages or OpenCV itself personally, so there may be further issues I'm not seeing, but I would guess that any difficulty you've encountered was a matter of build tools and system configuration, not the libraries themselves.

I have found it necessary on multiple occasions to do manual tweaks and jury-rigging when installing FFI bindings from Hackage on Windows, as opposed to the typically seamless process of installing an external library from standard repositories on Ubuntu and then bindings from Hackage. Admittedly this may be due in large part to the horrendous condition of build tools on my Windows system. I believe I have two different GHCs and no less than four copies of GCC in different locations and I've given up on making sense of it since I'm rarely on my Windows machine when coding Haskell anyway.

Incidentally, have you looked at what functionality the bindings packages offer? Both that I saw on Hackage seem to advertise themselves as emphatically not production-ready code and probably don't expose all the features of OpenCV. Before you put a lot of time into fixing build problems, you may want to verify that they even provide what you need. As a last resort, writing your own Haskell FFI bindings to a C library is sometimes tedious but not usually difficult, and there are tools to help automate the task.

I'm not aware of any other existing packages in Haskell for image processing or computer vision. Depending on what you need, you could write FFI bindings (to OpenCV or something else) or, if you mostly want to work with raw data instead of using algorithms provided by the library, there was actually a question on Stack Overflow recently that may be relevant: http://stackoverflow.com/questions/6006304

- C.

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