Smartphone image processing development made easy!

A very popular open source C# project for image processing, neural networks, machine learning etc. is the AForge.NET Framework, developed by Andrew Kirillow. AForge.NET has been used in numerous applications. It also forms the basis for the Accord.NET Framework, developed by César de Souza, which substantially extends AForge.NET with additional image processing filters, machine learning algorithms, statistical distributions and much much more. Numerous examples of what Accord.NET Framework is capable of are available here.

AForge.NET was developed to run on the .NET Framework and uses the System.Drawing assembly as basis for image manipulation and processing. In particular the dependency on System.Drawing heavily limits the applicability of AForge.NET (and subsequently, Accord.NET) to more modern platforms, like WPF, Windows (for tablet and desktop, as opposed to desktop-only applications), and Windows Phone.

It seemed like a terrible waste that these frameworks would only be available to the outdated range of Windows Forms applications. So, to enable the invaluable functionality of AForge.NET and Accord.NET for modern Microsoft platforms, I started the project of porting these frameworks into Portable Class Libraries, PCL. These efforts are also open sourced and are available on Github: Portable AForge and Portable Accord.

It should be noted that Portable AForge and Portable Accord cover a subset of the assemblies in the pure .NET based frameworks. Video and robotics support is not included, and audio support is limited. Windows Forms UI controls have not been ported. Nevertheless, practically all image processing and scientific computing functionality is included in the portable frameworks.

To facilitate continuous inclusion of updated code for the two frameworks, I have striven to keep the original AForge.NET and Accord.NET code bases as untouched as realistically possible. To cover up for those parts of the framework codes that are not applicable in the portable class libraries, I have therefore developed two support assemblies called Shim and Shim.Drawing.

Shim, which contains simple implementations of non-UI types and methods unavailable in the PCL profiles, is maintained in a separate Github repository, since this assembly is also immediately applicable as a legacy code bridge in other modern target adaptations, such as the port of the fo-dicom library to the (modern) Windows and Windows Phone platforms.

Shim.Drawing is internal to the Portable AForge and Accord assemblies, and is contained in the Portable AForge Github repository. It provides a down-scaled replacement for the System.Drawing assembly. Along with the platforms of primary interest, Shim.Drawing can also be contained in a .NET Framework WPF project as long as System.Drawing is not simultaneously referenced. Portable AForge and Accord is thus a also shortcut to using AForge.NET and Accord.NET in WPF applications.

To enable the portable framework assemblies on a specific target platform, the Shim and Shim.Drawing assemblies come in various flavors. There are for example specific Windows Phone (Silverlight) 8 versions of Shim and Shim.Drawing that should be referenced in a WP8 application using the Portable AForge and Accord assemblies.

Currently, Portable AForge and Portable Accord are available for the following target platforms:

• .NET Framework 4.5 and higher (for WPF applications)
• Windows 8 and higher (modern tablet/desktop applications)
• Windows Phone Silverlight 8 and higher
• Universal applications, i.e. Windows Phone 8.1 + Windows 8.1
• Xamarin.iOS
• Xamarin.Android

Yes, you read it right! My most recent developments also incorporate the ability to target the Xamarin.iOS and Xamarin.Android platforms. The Xamarin assemblies are however not available as open source. If you are interested in developing AForge and Accord based applications for Xamarin.iOS and/or Xamarin.Android, please contact me directly at licenses@cureos.com.

And now, with AForge and Accord available on the three mobile platforms, cross-platform development using Xamarin.Forms has also become a reality! This means that it is practically possible to contain an entire C# code base in a PCL core library that uses AForge and Accord, and consume this core library from end applications for all three mobile platforms, Windows Phone, Xamarin.iOS and Xamarin.Android.

Just to show what can now be very quickly done, I copied the functionality of the Face Detection (Haar Object Selector) sample application from the Accord.NET samples and contained it in a Xamarin.Forms project. All application code, including setting up the graphical layout and the face detection operation, is contained in the PCL core project. The platform specific end application projects only wrap the core assembly.

And this is what the face detection sample application looks like on the three mobile platforms:

A first small step, perhaps, but the possibilities that have now been opened up are practically infinite :-)

Getting the grip on your version control

I have recently been working with several different open-source projects that are available on Google Code, Github, CodePlex etc. The projects tend to use different software for managing version control, which in turn requires multiple SCM clients to be installed on the development system.

Version control software commonly used in open-source projects today include Subversion, Git and Mercurial. By default, the version control software is accessed through command-line interfaces. However, there are several different GUI wrappers available to facilitate the version control management. On Windows, different flavors of Tortoise are predominantly used. These tools are primarily shell extensions, enabling version control management inside Windows Explorer. TortoiseCVS for CVS version control was first in line, and it has inspired or formed the basis to followers like TortoiseSVN, TortoiseGit and TortoiseHg.

The various Tortoise tools makes version control management much easier and more efficient, and there is normally no problem having several of these tools installed at once on the same computer.

There is one annoying issue though: all the above tools use the same icons and icon overlays in Windows Explorer. It is therefore not immediately possible in Windows Explorer to determine which version control software that is being used to manage a specific folder.

Of course, if you enter the folder the version control administration sub-folders (.svn, .git, .hg, etc.) will be listed if you have configured Windows Explorer to display hidden folders. But this is a sub-optimal behavior; ideally the version control software should be detectable through some indication in the Windows Explorer list, or when hovering the mouse over the folder in question.

In case someone had experienced the same annoyance as I and found a workaround for it, I posted a question on the subject at StackOverflow. I got a few answers primarily explaining why the same icon overlays are used, but then I also got an eye-opening answer from Stefan Küng, lead developer of TortoiseSVN. Stefan suggested me to customize the version controlled top folder using the approach described here. This was exactly what I had looked for: a method for customizing the folder layout and provide explanatory text in the tool-tip when hovering over the folder with the mouse pointer!

My only remaining concern now was that I would have to do this customization manually for each version controlled folder, which would be quite tedious and error-prone when a large number of projects are involved.

But then, what do developers do, if not implementing solutions to repetitive problems?

Thus, I took the bull by the horns and came up with a simple yet efficient console application for managing the folder customization. The application identifies the version control software used in the specified folder, adds a tool-tip and sets the folder icon to indicate which software that is being used to version control the folder. Currently, the application identifies Subversion, Git and Mercurial, but if the conditions are right (version control administration files in a sub-folder with a fix name) it is a straightforward task to extend this list of software. The application source code is available under an open-source license (Eclipse Public License version 1.0) and can be obtained from here.

After running the application on the version-controlled folders in the image above, Windows Explorer will (after a few refreshes) provide the following display:

Hovering with the mouse pointer over a version control decorated folder will clearly indicate the version control software being used:

It is even possible to run the folder decorator application without changing the folder icons. If the icons are not available in the same directory as the folder decorator application, the classic folder icon will be maintained but the tool-tip will still be updated.

The icons have been obtained from the Open Icon Library. The Subversion icon is "Sub-optimal"; I was not able to find a better redistributable Subversion icon. For personal, non-redistributable use, a more identifiable Subversion icon is available here. If you so wish, download this Subversion icon file instead, rename it to svn.ico and replace the existing Subversion icon in the Visual Studio project with the downloaded one.

Happy version-controlling!